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Viruses, Volume 4, Issue 11 (November 2012), Pages 2417-3269

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Research

Jump to: Review

Open AccessArticle Insights into the Functions of a Prophage Recombination Directionality Factor
Viruses 2012, 4(11), 2417-2431; doi:10.3390/v4112417
Received: 21 August 2012 / Revised: 4 October 2012 / Accepted: 5 October 2012 / Published: 24 October 2012
Cited by 4 | PDF Full-text (1678 KB) | HTML Full-text | XML Full-text
Abstract
Recombination directionality factors (RDFs), or excisionases, are essential players of prophage excisive recombination. Despite the essentially catalytic role of the integrase in both integrative and excisive recombination, RDFs are required to direct the reaction towards excision and to prevent re-integration of the [...] Read more.
Recombination directionality factors (RDFs), or excisionases, are essential players of prophage excisive recombination. Despite the essentially catalytic role of the integrase in both integrative and excisive recombination, RDFs are required to direct the reaction towards excision and to prevent re-integration of the prophage genome when entering a lytic cycle. KplE1, HK620 and numerous (pro)phages that integrate at the same site in enterobacteria genomes (such as the argW tRNA gene) all share a highly conserved recombination module. This module comprises the attL and attR recombination sites and the RDF and integrase genes. The KplE1 RDF was named TorI after its initial identification as a negative regulator of the tor operon. However, it was characterized as an essential factor of excisive recombination. In this study, we designed an extensive random mutagenesis protocol of the torI gene and identified key residues involved in both functions of the TorI protein. We show that, in addition to TorI-TorR protein-protein interaction, TorI interacts in solution with the IntS integrase. Moreover, in vitro, TorR and IntS appear to compete for TorI binding. Finally, our mutagenesis results suggest that the C-terminal part of the TorI protein is dedicated to protein-protein interactions with both proteins TorR and IntS. Full article
(This article belongs to the Special Issue Recent Progress in Bacteriophage Research) Print Edition available
Open AccessArticle Diversity and Adaptation of Human Respiratory Syncytial Virus Genotypes Circulating in Two Distinct Communities: Public Hospital and Day Care Center
Viruses 2012, 4(11), 2432-2447; doi:10.3390/v4112432
Received: 31 August 2012 / Revised: 16 October 2012 / Accepted: 17 October 2012 / Published: 24 October 2012
Cited by 2 | PDF Full-text (467 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
HRSV is one of the most important pathogens causing acute respiratory tract diseases as bronchiolitis and pneumonia among infants. HRSV was isolated from two distinct communities, a public day care center and a public hospital in São José do Rio Preto – [...] Read more.
HRSV is one of the most important pathogens causing acute respiratory tract diseases as bronchiolitis and pneumonia among infants. HRSV was isolated from two distinct communities, a public day care center and a public hospital in São José do Rio Preto – SP, Brazil. We obtained partial sequences from G gene that were used on phylogenetic and selection pressure analysis. HRSV accounted for 29% of respiratory infections in hospitalized children and 7.7% in day care center children. On phylogenetic analysis of 60 HRSV strains, 48 (80%) clustered within or adjacent to the GA1 genotype; GA5, NA1, NA2, BA-IV and SAB1 were also observed. SJRP GA1 strains presented variations among deduced amino acids composition and lost the potential O-glycosilation site at amino acid position 295, nevertheless this resulted in an insertion of two potential O-glycosilation sites at positions 296 and 297. Furthermore, a potential O-glycosilation site insertion, at position 293, was only observed for hospital strains. Using SLAC and MEME methods, only amino acid 274 was identified to be under positive selection. This is the first report on HRSV circulation and genotypes classification derived from a day care center community in Brazil. Full article
(This article belongs to the Special Issue Pneumoviruses and Metapneumoviruses)
Open AccessArticle Human Cytomegalovirus Encoded Homologs of Cytokines, Chemokines and their Receptors: Roles in Immunomodulation
Viruses 2012, 4(11), 2448-2470; doi:10.3390/v4112448
Received: 30 September 2012 / Revised: 24 October 2012 / Accepted: 24 October 2012 / Published: 25 October 2012
Cited by 20 | PDF Full-text (642 KB) | HTML Full-text | XML Full-text
Abstract
Human cytomegalovirus (HCMV), the largest human herpesvirus, infects a majority of the world’s population. Like all herpesviruses, following primary productive infection, HCMV establishes a life-long latent infection, from which it can reactivate years later to produce new, infectious virus. Despite the presence [...] Read more.
Human cytomegalovirus (HCMV), the largest human herpesvirus, infects a majority of the world’s population. Like all herpesviruses, following primary productive infection, HCMV establishes a life-long latent infection, from which it can reactivate years later to produce new, infectious virus. Despite the presence of a massive and sustained anti-HCMV immune response, productively infected individuals can shed virus for extended periods of time, and once latent infection is established, it is never cleared from the host. It has been proposed that HCMV must therefore encode functions which help to evade immune mediated clearance during productive virus replication and latency. Molecular mimicry is a strategy used by many viruses to subvert and regulate anti-viral immunity and HCMV has hijacked/developed a range of functions that imitate host encoded immunomodulatory proteins. This review will focus on the HCMV encoded homologs of cellular cytokines/chemokines and their receptors, with an emphasis on how these virus encoded homologs may facilitate viral evasion of immune clearance. Full article
(This article belongs to the Special Issue Immune Evasion)
Open AccessArticle Niemann-Pick C1 (NPC1)/NPC1-like1 Chimeras Define Sequences Critical for NPC1’s Function as a Filovirus Entry Receptor
Viruses 2012, 4(11), 2471-2484; doi:10.3390/v4112471
Received: 22 August 2012 / Revised: 10 October 2012 / Accepted: 18 October 2012 / Published: 25 October 2012
Cited by 16 | PDF Full-text (1209 KB) | HTML Full-text | XML Full-text
Abstract
We recently demonstrated that Niemann-Pick C1 (NPC1), a ubiquitous 13-pass cellular membrane protein involved in lysosomal cholesterol transport, is a critical entry receptor for filoviruses. Here we show that Niemann-Pick C1-like1 (NPC1L1), an NPC1 paralog and hepatitis C virus entry factor, lacks [...] Read more.
We recently demonstrated that Niemann-Pick C1 (NPC1), a ubiquitous 13-pass cellular membrane protein involved in lysosomal cholesterol transport, is a critical entry receptor for filoviruses. Here we show that Niemann-Pick C1-like1 (NPC1L1), an NPC1 paralog and hepatitis C virus entry factor, lacks filovirus receptor activity. We exploited the structural similarity between NPC1 and NPC1L1 to construct and analyze a panel of chimeras in which NPC1L1 sequences were replaced with cognate sequences from NPC1. Only one chimera, NPC1L1 containing the second luminal domain (C) of NPC1 in place of its own, bound to the viral glycoprotein, GP. This engineered protein mediated authentic filovirus infection nearly as well as wild-type NPC1, and more efficiently than did a minimal NPC1 domain C-based receptor recently described by us. A reciprocal chimera, NPC1 containing NPC1L1’s domain C, was completely inactive. Remarkably, an intra-domain NPC1L1-NPC1 chimera bearing only a ~130-amino acid N–terminal region of NPC1 domain C could confer substantial viral receptor activity on NPC1L1. Taken together, these findings account for the failure of NPC1L1 to serve as a filovirus receptor, highlight the central role of the luminal domain C of NPC1 in filovirus entry, and reveal the direct involvement of N–terminal domain C sequences in NPC1’s function as a filovirus receptor. Full article
(This article belongs to the Special Issue Advances in Filovirus Research 2012) Print Edition available
Open AccessArticle How much of Virus-Specific CD8 T Cell Reactivity is Detected with a Peptide Pool when Compared to Individual Peptides?
Viruses 2012, 4(11), 2636-2649; doi:10.3390/v4112636
Received: 27 September 2012 / Revised: 17 October 2012 / Accepted: 17 October 2012 / Published: 29 October 2012
Cited by 3 | PDF Full-text (862 KB) | HTML Full-text | XML Full-text
Abstract
Immune monitoring of T cell responses increasingly relies on the use of peptide pools. Peptides, when restricted by the same HLA allele, and presented from within the same peptide pool, can compete for HLA binding sites. What impact such competition has on [...] Read more.
Immune monitoring of T cell responses increasingly relies on the use of peptide pools. Peptides, when restricted by the same HLA allele, and presented from within the same peptide pool, can compete for HLA binding sites. What impact such competition has on functional T cell stimulation, however, is not clear. Using a model peptide pool that is comprised of 32 well-defined viral epitopes from Cytomegalovirus, Epstein-Barr virus, and Influenza viruses (CEF peptide pool), we assessed peptide competition in PBMC from 42 human subjects. The magnitude of the peptide pool-elicited CD8 T cell responses was a mean 79% and a median 77% of the sum of the CD8 T cell responses elicited by the individual peptides. Therefore, while the effect of peptide competition was evident, it was of a relatively minor magnitude. By studying the dose-response curves for individual CEF peptides, we show that several of these peptides are present in the CEF-pool at concentrations that are orders of magnitude in excess of what is needed for the activation threshold of the CD8 T cells. The presence of such T cells with very high functional avidity for the viral antigens can explain why the effect of peptide competition is relatively minor within the CEF-pool. Full article
Open AccessArticle Comparative Genomics of Korean Infectious Bronchitis Viruses (IBVs) and an Animal Model to Evaluate Pathogenicity of IBVs to the Reproductive Organs
Viruses 2012, 4(11), 2670-2683; doi:10.3390/v4112670
Received: 23 August 2012 / Revised: 18 October 2012 / Accepted: 18 October 2012 / Published: 30 October 2012
Cited by 5 | PDF Full-text (676 KB) | HTML Full-text | XML Full-text
Abstract
The K-I and nephropathogenic K-II genotypes of infectious bronchitis virus (IBV) have been isolated since 1995 and 1990, respectively, in Korea and commercial inactivated oil-emulsion vaccines containing KM91 (K-II type) and Massachusetts 41 strains have been used in the field. To date, [...] Read more.
The K-I and nephropathogenic K-II genotypes of infectious bronchitis virus (IBV) have been isolated since 1995 and 1990, respectively, in Korea and commercial inactivated oil-emulsion vaccines containing KM91 (K-II type) and Massachusetts 41 strains have been used in the field. To date, genomic analyses of Korean IBV strains and animal models to test the pathogenicity of Korean IBVs to the reproductive organs have been rare. In the present study, comparative genomics of SNU8067 (K-I type) and KM91 IBVs was performed, and an animal model to test the pathogenicity of SNU8067 was established and applied to vaccine efficacy test. The genome sizes of SNU8067 (27,708 nt) and KM91 (27,626 nt) were slightly different and the nucleotide and amino acid identities of the S1 (79%, 77%), 3a (65%, 52%), and 3b (81%, 72%) genes were lower than those of other genes (94%–97%, 92%–98%). A recombination analysis revealed that SNU8067 was a recombinant virus with a KM91-like backbone except S1, 3a, and 3b genes which might be from an unknown virus. An SNU8067 infection inhibited formation of hierarchal ovarian follicles (80%) and oviduct maturation (50%) in the control group, whereas 70% of vaccinated chickens were protected from lesions. Full article
(This article belongs to the Special Issue Perspectives and Challenges in Coronavirus Research)
Open AccessArticle Dendritic Cell Apoptosis and the Pathogenesis of Dengue
Viruses 2012, 4(11), 2736-2753; doi:10.3390/v4112736
Received: 12 October 2012 / Revised: 30 October 2012 / Accepted: 31 October 2012 / Published: 1 November 2012
Cited by 9 | PDF Full-text (869 KB) | HTML Full-text | XML Full-text
Abstract
Dengue viruses and other members of the Flaviviridae family are emerging human pathogens. Dengue is transmitted to humans by Aedes aegypti female mosquitoes. Following infection through the bite, cells of the hematopoietic lineage, like dendritic cells, are the first targets of dengue [...] Read more.
Dengue viruses and other members of the Flaviviridae family are emerging human pathogens. Dengue is transmitted to humans by Aedes aegypti female mosquitoes. Following infection through the bite, cells of the hematopoietic lineage, like dendritic cells, are the first targets of dengue virus infection. Dendritic cells (DCs) are key antigen presenting cells, sensing pathogens, processing and presenting the antigens to T lymphocytes, and triggering an adaptive immune response. Infection of DCs by dengue virus may induce apoptosis, impairing their ability to present antigens to T cells, and thereby contributing to dengue pathogenesis. This review focuses on general mechanisms by which dengue virus triggers apoptosis, and possible influence of DC-apoptosis on dengue disease severity. Full article
(This article belongs to the Special Issue Modulation of Apoptosis by Viral Infection)
Figures

Open AccessArticle Use of an Innovative Web-Based Laboratory Surveillance Platform to Analyze Mixed Infections Between Human Metapneumovirus (hMPV) and Other Respiratory Viruses Circulating in Alberta (AB), Canada (2009–2012)
Viruses 2012, 4(11), 2754-2765; doi:10.3390/v4112754
Received: 30 August 2012 / Revised: 12 October 2012 / Accepted: 26 October 2012 / Published: 5 November 2012
Cited by 5 | PDF Full-text (321 KB) | HTML Full-text | XML Full-text
Abstract
We investigated the proportions of mono vs. mixed infections for human metapneumovirus (hMPV) as compared to adenovirus (ADV), four types of coronavirus (CRV), parainfluenza virus (PIV), RSV, and enterovirus/rhinovirus (ERV) in Alberta, Canada. Using the Data Integration for Alberta Laboratories (DIAL) platform, 26,226 respiratory specimens at ProvLab between 1 July 2009 and 30 June 2012 were selected and included in the study. Using the Respiratory Virus Panel these specimens tested positive for one or more respiratory virus and negative for influenza A and B. From our subset hMPV was the fourth most common virus (n=2,561) with 373 (15%) identified as mixed infection using DIAL. Mixed infection with hMPV was most commonly found in infants less than 6 months old and ERV was most commonly found in mixed infection with hMPV (230/373, 56%) across all age groups. The proportion of mixed-infection vs. mono-infection was highest for ADV (46%), followed by CRV 229E (32%), CRV HKU1 (31%), CRV NL63 (28%), CRV OC43 (23%), PIV (20%), RSV (17%), hMPV (15%) and ERV (13%). hMPV was significantly more likely to be identified in mono infection as compared with ADV, CRV, PIV, and RSV with the exception of ERV [p < 0.05]. Full article
(This article belongs to the Special Issue Pneumoviruses and Metapneumoviruses)
Open AccessArticle Discovery and Early Development of AVI-7537 and AVI-7288 for the Treatment of Ebola Virus and Marburg Virus Infections
Viruses 2012, 4(11), 2806-2830; doi:10.3390/v4112806
Received: 3 September 2012 / Revised: 2 October 2012 / Accepted: 2 October 2012 / Published: 6 November 2012
Cited by 47 | PDF Full-text (458 KB) | HTML Full-text | XML Full-text
Abstract
There are no currently approved treatments for filovirus infections. In this study we report the discovery process which led to the development of antisense Phosphorodiamidate Morpholino Oligomers (PMOs) AVI-6002 (composed of AVI-7357 and AVI-7539) and AVI-6003 (composed of AVI-7287 and AVI-7288) targeting [...] Read more.
There are no currently approved treatments for filovirus infections. In this study we report the discovery process which led to the development of antisense Phosphorodiamidate Morpholino Oligomers (PMOs) AVI-6002 (composed of AVI-7357 and AVI-7539) and AVI-6003 (composed of AVI-7287 and AVI-7288) targeting Ebola virus and Marburg virus respectively. The discovery process involved identification of optimal transcript binding sites for PMO based RNA-therapeutics followed by screening for effective viral gene target in mouse and guinea pig models utilizing adapted viral isolates. An evolution of chemical modifications were tested, beginning with simple Phosphorodiamidate Morpholino Oligomers (PMO) transitioning to cell penetrating peptide conjugated PMOs (PPMO) and ending with PMOplus containing a limited number of positively charged linkages in the PMO structure. The initial lead compounds were combinations of two agents targeting separate genes. In the final analysis, a single agent for treatment of each virus was selected, AVI-7537 targeting the VP24 gene of Ebola virus and AVI-7288 targeting NP of Marburg virus, and are now progressing into late stage clinical development as the optimal therapeutic candidates. Full article
(This article belongs to the Special Issue Advances in Filovirus Research 2012) Print Edition available
Open AccessArticle Rapid Detection and Differentiation of Swine-Origin Influenza A Virus (H1N1/2009) from Other Seasonal Influenza A Viruses
Viruses 2012, 4(11), 3012-3019; doi:10.3390/v4113012
Received: 25 August 2012 / Revised: 1 November 2012 / Accepted: 1 November 2012 / Published: 9 November 2012
Cited by 8 | PDF Full-text (449 KB) | HTML Full-text | XML Full-text
Abstract
We previously developed a rapid and simple gold nanoparticle(NP)-based genomic microarray assay for identification of the avian H5N1 virus and its discrimination from other influenza A virus strains (H1N1, H3N2). In this study, we expanded the platform to detect the 2009 swine-origin [...] Read more.
We previously developed a rapid and simple gold nanoparticle(NP)-based genomic microarray assay for identification of the avian H5N1 virus and its discrimination from other influenza A virus strains (H1N1, H3N2). In this study, we expanded the platform to detect the 2009 swine-origin influenza A virus (H1N1/2009). Multiple specific capture and intermediate oligonucleotides were designed for the matrix (M), hemagglutinin (HA), and neuraminidase (NA) genes of the H1N1/2009 virus. The H1N1/2009 microarrays were printed in the same format as those of the seasonal influenza H1N1 and H3N2 for the HA, NA, and M genes. Viral RNA was tested using capture-target-intermediate oligonucleotide hybridization and gold NP-mediated silver staining. The signal from the 4 capture-target-intermediates of the HA and NA genes was specific for H1N1/2009 virus and showed no cross hybridization with viral RNA from other influenza strains H1N1, H3N2, and H5N1. All of the 3 M gene captures showed strong affinity with H1N1/2009 viral RNA, with 2 out of the 3 M gene captures showing cross hybridization with the H1N1, H3N2, and H5N1 samples tested. The current assay was able to detect H1N1/2009 and distinguish it from other influenza A viruses. This new method may be useful for simultaneous detection and subtyping of influenza A viruses and can be rapidly modified to detect other emerging influenza strains in public health settings. Full article
(This article belongs to the Special Issue H5N1 Influenza Virus)
Open AccessArticle Spatio-Temporal Dynamics of Viruses are Differentially Affected by Parasitoids Depending on the Mode of Transmission
Viruses 2012, 4(11), 3069-3089; doi:10.3390/v4113069
Received: 1 October 2012 / Revised: 18 October 2012 / Accepted: 31 October 2012 / Published: 12 November 2012
Cited by 12 | PDF Full-text (2186 KB) | HTML Full-text | XML Full-text
Abstract
Relationships between agents in multitrophic systems are complex and very specific. Insect-transmitted plant viruses are completely dependent on the behaviour and distribution patterns of their vectors. The presence of natural enemies may directly affect aphid behaviour and spread of plant viruses, as [...] Read more.
Relationships between agents in multitrophic systems are complex and very specific. Insect-transmitted plant viruses are completely dependent on the behaviour and distribution patterns of their vectors. The presence of natural enemies may directly affect aphid behaviour and spread of plant viruses, as the escape response of aphids might cause a potential risk for virus dispersal. The spatio-temporal dynamics of Cucumber mosaic virus (CMV) and Cucurbit aphid-borne yellows virus (CABYV), transmitted by Aphis gossypii in a non-persistent and persistent manner, respectively, were evaluated at short and long term in the presence and absence of the aphid parasitoid, Aphidius colemani. SADIE methodology was used to study the distribution patterns of both the virus and its vector, and their degree of association. Results suggested that parasitoids promoted aphid dispersion at short term, which enhanced CMV spread, though consequences of parasitism suggest potential benefits for disease control at long term. Furthermore, A. colemani significantly limited the spread and incidence of the persistent virus CABYV at long term. The impact of aphid parasitoids on the dispersal of plant viruses with different transmission modes is discussed. Full article
(This article belongs to the Special Issue Plant Viruses)
Open AccessArticle Virus Pathogen Database and Analysis Resource (ViPR): A Comprehensive Bioinformatics Database and Analysis Resource for the Coronavirus Research Community
Viruses 2012, 4(11), 3209-3226; doi:10.3390/v4113209
Received: 2 October 2012 / Revised: 13 November 2012 / Accepted: 14 November 2012 / Published: 19 November 2012
Cited by 13 | PDF Full-text (1534 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Several viruses within the Coronaviridae family have been categorized as either emerging or re-emerging human pathogens, with Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) being the most well known. The NIAID-sponsored Virus Pathogen Database and Analysis Resource (ViPR, www.viprbrc.org) supports bioinformatics workflows for [...] Read more.
Several viruses within the Coronaviridae family have been categorized as either emerging or re-emerging human pathogens, with Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) being the most well known. The NIAID-sponsored Virus Pathogen Database and Analysis Resource (ViPR, www.viprbrc.org) supports bioinformatics workflows for a broad range of human virus pathogens and other related viruses, including the entire Coronaviridae family. ViPR provides access to sequence records, gene and protein annotations, immune epitopes, 3D structures, host factor data, and other data types through an intuitive web-based search interface. Records returned from these queries can then be subjected to web-based analyses including: multiple sequence alignment, phylogenetic inference, sequence variation determination, BLAST comparison, and metadata-driven comparative genomics statistical analysis. Additional tools exist to display multiple sequence alignments, view phylogenetic trees, visualize 3D protein structures, transfer existing reference genome annotations to new genomes, and store or share results from any search or analysis within personal private ‘Workbench’ spaces for future access. All of the data and integrated analysis and visualization tools in ViPR are made available without charge as a service to the Coronaviridae research community to facilitate the research and development of diagnostics, prophylactics, vaccines and therapeutics against these human pathogens. Full article
(This article belongs to the Special Issue Perspectives and Challenges in Coronavirus Research)
Open AccessArticle Safety and Immunogenicity of a Plant-Produced Recombinant Hemagglutinin-Based Influenza Vaccine (HAI-05) Derived from A/Indonesia/05/2005 (H5N1) Influenza Virus: A Phase 1 Randomized, Double-Blind, Placebo-Controlled, Dose-Escalation Study in Healthy Adults
Viruses 2012, 4(11), 3227-3244; doi:10.3390/v4113227
Received: 25 October 2012 / Revised: 15 November 2012 / Accepted: 16 November 2012 / Published: 19 November 2012
Cited by 18 | PDF Full-text (400 KB) | HTML Full-text | XML Full-text
Abstract
Recently, we have reported [1,2] on a subunit influenza vaccine candidate based on the recombinant hemagglutinin protein from the A/Indonesia/05/2005 (H5N1) strain of influenza virus, produced it using ‘launch vector’-based transient expression technology in Nicotiana benthamiana, and demonstrated its immunogenicity in [...] Read more.
Recently, we have reported [1,2] on a subunit influenza vaccine candidate based on the recombinant hemagglutinin protein from the A/Indonesia/05/2005 (H5N1) strain of influenza virus, produced it using ‘launch vector’-based transient expression technology in Nicotiana benthamiana, and demonstrated its immunogenicity in pre-clinical studies. Here, we present the results of a first-in-human, Phase 1 randomized, double-blind, placebo-controlled study designed to investigate safety, reactogenicity and immunogenicity of three escalating dose levels of this vaccine, HAI-05, (15, 45 and 90 µg) adjuvanted with Alhydrogel® (0.75 mg aluminum per dose) and the 90 µg dose level without Alhydrogel®. Vaccine was administered intramuscularly in two injections three weeks apart to healthy adults of 18–49 years of age. At all dose levels the vaccine was generally safe and well tolerated, with no reported serious adverse events or dose-limiting toxicities. Mild local and systemic reactions were observed in all vaccine dose groups and the placebo group and their occurrence was not dose related. The incidence rates were higher in the groups receiving vaccine with Alhydrogel®. The immune response elicited by the HAI-05 vaccine was variable with respect to both hemagglutination-inhibition and virus microneutralization antibody titers, with the highest responses observed in the 90 µg unadjuvanted group. Full article
(This article belongs to the Special Issue H5N1 Influenza Virus)

Review

Jump to: Research

Open AccessReview MicroRNAs, Hepatitis C Virus, and HCV/HIV-1 Co-Infection: New Insights in Pathogenesis and Therapy
Viruses 2012, 4(11), 2485-2513; doi:10.3390/v4112485
Received: 31 August 2012 / Revised: 17 October 2012 / Accepted: 18 October 2012 / Published: 26 October 2012
Cited by 16 | PDF Full-text (2164 KB) | HTML Full-text | XML Full-text
Abstract
MicroRNAs (miRNAs) can exert a profound effect on Hepatitis C virus (HCV) replication. The interaction of HCV with the highly liver-enriched miRNA, miR-122 represents one such unique example of viruses having evolved mechanism(s) to usurp the host miRNA machinery to support viral [...] Read more.
MicroRNAs (miRNAs) can exert a profound effect on Hepatitis C virus (HCV) replication. The interaction of HCV with the highly liver-enriched miRNA, miR-122 represents one such unique example of viruses having evolved mechanism(s) to usurp the host miRNA machinery to support viral life cycle. Furthermore, HCV infection can also trigger changes in the cellular miRNA profile, which may ultimately contribute to the outcome of viral infection. Accumulating knowledge on HCV-host miRNA interactions has ultimately influenced the design of therapeutic interventions against chronic HCV infection. The importance of microRNA modulation in Human Immunodeficiency Virus (HIV-1) replication has been reported, albeit only in the context of HIV-1 mono-infection. The development of HCV infection is dramatically influenced during co-infection with HIV-1. Here, we review the current knowledge on miRNAs in HCV mono-infection. In addition, we discuss the potential role of some miRNAs, identified from the analyses of public data, in HCV/HIV-1 co-infection. Full article
(This article belongs to the Special Issue Viruses and miRNAs)
Open AccessReview Advanced Vaccine Candidates for Lassa Fever
Viruses 2012, 4(11), 2514-2557; doi:10.3390/v4112514
Received: 27 September 2012 / Revised: 20 October 2012 / Accepted: 22 October 2012 / Published: 29 October 2012
Cited by 11 | PDF Full-text (1116 KB) | HTML Full-text | XML Full-text
Abstract
Lassa virus (LASV) is the most prominent human pathogen of the Arenaviridae. The virus is transmitted to humans by a rodent reservoir, Mastomys natalensis, and is capable of causing lethal Lassa Fever (LF). LASV has the highest human impact of any of [...] Read more.
Lassa virus (LASV) is the most prominent human pathogen of the Arenaviridae. The virus is transmitted to humans by a rodent reservoir, Mastomys natalensis, and is capable of causing lethal Lassa Fever (LF). LASV has the highest human impact of any of the viral hemorrhagic fevers (with the exception of Dengue Fever) with an estimated several hundred thousand infections annually, resulting in thousands of deaths in Western Africa. The sizeable disease burden, numerous imported cases of LF in non-endemic countries, and the possibility that LASV can be used as an agent of biological warfare make a strong case for vaccine development. Presently there is no licensed vaccine against LF or approved treatment. Recently, several promising vaccine candidates have been developed which can potentially target different groups at risk. The purpose of this manuscript is to review the LASV pathogenesis and immune mechanisms involved in protection. The current status of pre-clinical development of the advanced vaccine candidates that have been tested in non-human primates will be discussed. Major scientific, manufacturing, and regulatory challenges will also be considered. Full article
(This article belongs to the Special Issue Arenaviruses)
Open AccessReview Cyclophilin Inhibitors: An Emerging Class of Therapeutics for the Treatment of Chronic Hepatitis C Infection
Viruses 2012, 4(11), 2558-2577; doi:10.3390/v4112558
Received: 3 September 2012 / Revised: 18 October 2012 / Accepted: 20 October 2012 / Published: 29 October 2012
Cited by 15 | PDF Full-text (394 KB) | HTML Full-text | XML Full-text
Abstract
The advent of the replicon system together with advances in cell culture have contributed significantly to our understanding of the function of virally-encoded structural and nonstructural proteins in the replication cycle of the hepatitis C virus. In addition, in vitro systems have been [...] Read more.
The advent of the replicon system together with advances in cell culture have contributed significantly to our understanding of the function of virally-encoded structural and nonstructural proteins in the replication cycle of the hepatitis C virus. In addition, in vitro systems have been used to identify several host proteins whose expression is critical for supporting such diverse activities as viral entry, RNA replication, particle assembly, and the release of infectious virions. Among all known host proteins that participate in the HCV replication cycle, cyclophilins are unique because they constitute the only host target that has formed the basis of pharmaceutical drug discovery and drug development programs. The introduction of the nonimmunosuppressive cyclophilin inhibitors into clinical testing has confirmed the clinical utility of CsA-based inhibitors for the treatment of individuals with chronic hepatitis C infection and has yielded new insights into their mechanism(s) of action. This review describes the biochemical evidence for the potential roles played by cyclophilins in supporting HCV RNA replication and summarizes clinical trial results obtained with the first generation of nonimmunosuppressive cyclophilin inhibitors. Full article
(This article belongs to the Section Antivirals & Vaccines)
Open AccessReview Silencing and Innate Immunity in Plant Defense Against Viral and Non-Viral Pathogens
Viruses 2012, 4(11), 2578-2597; doi:10.3390/v4112578
Received: 27 September 2012 / Revised: 20 October 2012 / Accepted: 24 October 2012 / Published: 29 October 2012
Cited by 41 | PDF Full-text (451 KB) | HTML Full-text | XML Full-text
Abstract
The frontline of plant defense against non-viral pathogens such as bacteria, fungi and oomycetes is provided by transmembrane pattern recognition receptors that detect conserved pathogen-associated molecular patterns (PAMPs), leading to pattern-triggered immunity (PTI). To counteract this innate defense, pathogens deploy effector proteins [...] Read more.
The frontline of plant defense against non-viral pathogens such as bacteria, fungi and oomycetes is provided by transmembrane pattern recognition receptors that detect conserved pathogen-associated molecular patterns (PAMPs), leading to pattern-triggered immunity (PTI). To counteract this innate defense, pathogens deploy effector proteins with a primary function to suppress PTI. In specific cases, plants have evolved intracellular resistance (R) proteins detecting isolate-specific pathogen effectors, leading to effector-triggered immunity (ETI), an amplified version of PTI, often associated with hypersensitive response (HR) and programmed cell death (PCD). In the case of plant viruses, no conserved PAMP was identified so far and the primary plant defense is thought to be based mainly on RNA silencing, an evolutionary conserved, sequence-specific mechanism that regulates gene expression and chromatin states and represses invasive nucleic acids such as transposons. Endogenous silencing pathways generate 21-24 nt small (s)RNAs, miRNAs and short interfering (si)RNAs, that repress genes post-transcriptionally and/or transcriptionally. Four distinct Dicer-like (DCL) proteins, which normally produce endogenous miRNAs and siRNAs, all contribute to the biogenesis of viral siRNAs in infected plants. Growing evidence indicates that RNA silencing also contributes to plant defense against non-viral pathogens. Conversely, PTI-based innate responses may contribute to antiviral defense. Intracellular R proteins of the same NB-LRR family are able to recognize both non-viral effectors and avirulence (Avr) proteins of RNA viruses, and, as a result, trigger HR and PCD in virus-resistant hosts. In some cases, viral Avr proteins also function as silencing suppressors. We hypothesize that RNA silencing and innate immunity (PTI and ETI) function in concert to fight plant viruses. Viruses counteract this dual defense by effectors that suppress both PTI-/ETI-based innate responses and RNA silencing to establish successful infection. Full article
(This article belongs to the Special Issue Plant Viruses)
Open AccessReview dsRNA-Dependent Protein Kinase PKR and its Role in Stress, Signaling and HCV Infection
Viruses 2012, 4(11), 2598-2635; doi:10.3390/v4112598
Received: 4 September 2012 / Revised: 18 October 2012 / Accepted: 22 October 2012 / Published: 29 October 2012
Cited by 45 | PDF Full-text (2639 KB) | HTML Full-text | XML Full-text
Abstract
The double-stranded RNA-dependent protein kinase PKR plays multiple roles in cells, in response to different stress situations. As a member of the interferon (IFN)‑Stimulated Genes, PKR was initially recognized as an actor in the antiviral action of IFN, due to its ability to control [...] Read more.
The double-stranded RNA-dependent protein kinase PKR plays multiple roles in cells, in response to different stress situations. As a member of the interferon (IFN)‑Stimulated Genes, PKR was initially recognized as an actor in the antiviral action of IFN, due to its ability to control translation, through phosphorylation, of the alpha subunit of eukaryotic initiation factor 2 (eIF2a). As such, PKR participates in the generation of stress granules, or autophagy and a number of viruses have designed strategies to inhibit its action. However, PKR deficient mice resist most viral infections, indicating that PKR may play other roles in the cell other than just acting as an antiviral agent. Indeed, PKR regulates several signaling pathways, either as an adapter protein and/or using its kinase activity. Here we review the role of PKR as an eIF2a kinase, its participation in the regulation of the NF-kB, p38MAPK and insulin pathways, and we focus on its role during infection with the hepatitis C virus (HCV). PKR binds the HCV IRES RNA, cooperates with some functions of the HCV core protein and may represent a target for NS5A or E2. Novel data points out for a role of PKR as a pro-HCV agent, both as an adapter protein and as an eIF2a-kinase, and in cooperation with the di-ubiquitin-like protein ISG15. Developing pharmaceutical inhibitors of PKR may help in resolving some viral infections as well as stress-related damages. Full article
(This article belongs to the Special Issue Hepatitis C Pathology)
Open AccessReview Role of Lymphocytic Choriomeningitis Virus (LCMV) in Understanding Viral Immunology: Past, Present and Future
Viruses 2012, 4(11), 2650-2669; doi:10.3390/v4112650
Received: 30 September 2012 / Revised: 18 October 2012 / Accepted: 24 October 2012 / Published: 29 October 2012
Cited by 20 | PDF Full-text (726 KB) | HTML Full-text | XML Full-text
Abstract
Lymphocytic choriomeningitis virus (LCMV) is a common infection of rodents first identified over eighty years ago in St. Louis, MO, U.S.A. It is best known for its application in immunological studies. The history of LCMV closely correlates with the development of modern [...] Read more.
Lymphocytic choriomeningitis virus (LCMV) is a common infection of rodents first identified over eighty years ago in St. Louis, MO, U.S.A. It is best known for its application in immunological studies. The history of LCMV closely correlates with the development of modern immunology. With the use of LCMV as a model pathogen several key concepts have emerged: Major Histocompatibility Complex (MHC) restriction, T cell memory, persistent infections, T cell exhaustion and the key role of immune pathology in disease. Given the phenomenal infrastructure within this field (e.g., defined immunodominant and subdominant epitopes to all T cell receptor specificities as well as the cognate tetramers for enumeration in vivo) the study of LCMV remains an active and productive platform for biological research across the globe to this day. Here we present a historical primer that highlights several breakthroughs since the discovery of LCMV. Next, we highlight current research in the field and conclude with our predictions for future directions in the remarkable field of LCMV research. Full article
(This article belongs to the Special Issue Arenaviruses)
Open AccessReview Clinical Aspects of Feline Retroviruses: A Review
Viruses 2012, 4(11), 2684-2710; doi:10.3390/v4112684
Received: 12 October 2012 / Revised: 24 October 2012 / Accepted: 26 October 2012 / Published: 31 October 2012
Cited by 22 | PDF Full-text (432 KB) | HTML Full-text | XML Full-text
Abstract
Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are retroviruses with global impact on the health of domestic cats. The two viruses differ in their potential to cause disease. FeLV is more pathogenic, and was long considered to be responsible for [...] Read more.
Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are retroviruses with global impact on the health of domestic cats. The two viruses differ in their potential to cause disease. FeLV is more pathogenic, and was long considered to be responsible for more clinical syndromes than any other agent in cats. FeLV can cause tumors (mainly lymphoma), bone marrow suppression syndromes (mainly anemia), and lead to secondary infectious diseases caused by suppressive effects of the virus on bone marrow and the immune system. Today, FeLV is less commonly diagnosed than in the previous 20 years; prevalence has been decreasing in most countries. However, FeLV importance may be underestimated as it has been shown that regressively infected cats (that are negative in routinely used FeLV tests) also can develop clinical signs. FIV can cause an acquired immunodeficiency syndrome that increases the risk of opportunistic infections, neurological diseases, and tumors. In most naturally infected cats, however, FIV itself does not cause severe clinical signs, and FIV-infected cats may live many years without any health problems. This article provides a review of clinical syndromes in progressively and regressively FeLV-infected cats as well as in FIV-infected cats. Full article
(This article belongs to the Special Issue Feline Retroviruses)
Open AccessReview Advances and Future Challenges in Recombinant Adenoviral Vectored H5N1 Influenza Vaccines
Viruses 2012, 4(11), 2711-2735; doi:10.3390/v4112711
Received: 30 September 2012 / Revised: 22 October 2012 / Accepted: 25 October 2012 / Published: 1 November 2012
Cited by 12 | PDF Full-text (393 KB) | HTML Full-text | XML Full-text
Abstract
The emergence of a highly pathogenic avian influenza virus H5N1 has increased the potential for a new pandemic to occur. This event highlights the necessity for developing a new generation of influenza vaccines to counteract influenza disease. These vaccines must be manufactured [...] Read more.
The emergence of a highly pathogenic avian influenza virus H5N1 has increased the potential for a new pandemic to occur. This event highlights the necessity for developing a new generation of influenza vaccines to counteract influenza disease. These vaccines must be manufactured for mass immunization of humans in a timely manner. Poultry should be included in this policy, since persistent infected flocks are the major source of avian influenza for human infections. Recombinant adenoviral vectored H5N1 vaccines are an attractive alternative to the currently licensed influenza vaccines. This class of vaccines induces a broadly protective immunity against antigenically distinct H5N1, can be manufactured rapidly, and may allow mass immunization of human and poultry. Recombinant adenoviral vectors derived from both human and non-human adenoviruses are currently being investigated and appear promising both in nonclinical and clinical studies. This review will highlight the current status of various adenoviral vectored H5N1 vaccines and will outline novel approaches for the future. Full article
(This article belongs to the Section Antivirals & Vaccines)
Open AccessReview Immune Responses and Lassa Virus Infection
Viruses 2012, 4(11), 2766-2785; doi:10.3390/v4112766
Received: 30 September 2012 / Revised: 23 October 2012 / Accepted: 31 October 2012 / Published: 5 November 2012
Cited by 5 | PDF Full-text (1175 KB) | HTML Full-text | XML Full-text
Abstract
Lassa fever is a hemorrhagic fever endemic to West Africa and caused by Lassa virus, an Old World arenavirus. It may be fatal, but most patients recover from acute disease and some experience asymptomatic infection. The immune mechanisms associated with these different [...] Read more.
Lassa fever is a hemorrhagic fever endemic to West Africa and caused by Lassa virus, an Old World arenavirus. It may be fatal, but most patients recover from acute disease and some experience asymptomatic infection. The immune mechanisms associated with these different outcomes have not yet been fully elucidated, but considerable progress has recently been made, through the use of in vitro human models and nonhuman primates, the only relevant animal model that mimics the pathophysiology and immune responses induced in patients. We discuss here the roles of the various components of the innate and adaptive immune systems in Lassa virus infection and in the control of viral replication and pathogenesis. Full article
(This article belongs to the Special Issue Arenaviruses)
Open AccessReview Arenaviruses and Lethal Mutagenesis. Prospects for New Ribavirin-based Interventions
Viruses 2012, 4(11), 2786-2805; doi:10.3390/v4112786
Received: 11 October 2012 / Revised: 17 October 2012 / Accepted: 25 October 2012 / Published: 6 November 2012
Cited by 7 | PDF Full-text (979 KB) | HTML Full-text | XML Full-text
Abstract
Lymphocytic choriomeningitis virus (LCMV) has contributed to unveil some of the molecular mechanisms of lethal mutagenesis, or loss of virus infectivity due to increased mutation rates. Here we review these developments, and provide additional evidence that ribavirin displays a dual mutagenic and [...] Read more.
Lymphocytic choriomeningitis virus (LCMV) has contributed to unveil some of the molecular mechanisms of lethal mutagenesis, or loss of virus infectivity due to increased mutation rates. Here we review these developments, and provide additional evidence that ribavirin displays a dual mutagenic and inhibitory activity on LCMV that can be relevant to treatment designs. Using 5-fluorouracil as mutagenic agent and ribavirin either as inhibitor or mutagen, we document an advantage of a sequential inhibitor-mutagen administration over the corresponding combination treatment to achieve a low LCMV load in cell culture. This advantage is accentuated in the concentration range in which ribavirin acts mainly as an inhibitor, rather than as mutagen. This observation reinforces previous theoretical and experimental studies in supporting a sequential inhibitor-mutagen administration as a possible antiviral design. Given recent progress in the development of new inhibitors of arenavirus replication, our results suggest new options of ribavirin-based anti-arenavirus treatments. Full article
(This article belongs to the Special Issue Arenaviruses)
Open AccessReview New and Emerging Viruses of Blueberry and Cranberry
Viruses 2012, 4(11), 2831-2852; doi:10.3390/v4112831
Received: 4 October 2012 / Revised: 22 October 2012 / Accepted: 31 October 2012 / Published: 6 November 2012
Cited by 14 | PDF Full-text (2382 KB) | HTML Full-text | XML Full-text
Abstract
Blueberry and cranberry are fruit crops native to North America and they are well known for containing bioactive compounds that can benefit human health. Cultivation is expanding within North America and other parts of the world raising concern regarding distribution of existing [...] Read more.
Blueberry and cranberry are fruit crops native to North America and they are well known for containing bioactive compounds that can benefit human health. Cultivation is expanding within North America and other parts of the world raising concern regarding distribution of existing viruses as well as the appearance of new viruses. Many of the known viruses of these crops are latent or asymptomatic in at least some cultivars. Diagnosis and detection procedures are often non-existent or unreliable. Whereas new viruses can move into cultivated fields from the wild, there is also the threat that devastating viruses can move into native stands of Vaccinium spp. or other native plants from cultivated fields. The aim of this paper is to highlight the importance of blueberry and cranberry viruses, focusing not only on those that are new but also those that are emerging as serious threats for production in North America and around the world. Full article
(This article belongs to the Special Issue Plant Viruses)
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Open AccessReview Sharka: The Past, The Present and The Future
Viruses 2012, 4(11), 2853-2901; doi:10.3390/v4112853
Received: 15 October 2012 / Revised: 25 October 2012 / Accepted: 30 October 2012 / Published: 7 November 2012
Cited by 13 | PDF Full-text (1005 KB) | HTML Full-text | XML Full-text
Abstract
Members the Potyviridae family belong to a group of plant viruses that are causing devastating plant diseases with a significant impact on agronomy and economics. Plum pox virus (PPV), as a causative agent of sharka disease, is widely discussed. The understanding of [...] Read more.
Members the Potyviridae family belong to a group of plant viruses that are causing devastating plant diseases with a significant impact on agronomy and economics. Plum pox virus (PPV), as a causative agent of sharka disease, is widely discussed. The understanding of the molecular biology of potyviruses including PPV and the function of individual proteins as products of genome expression are quite necessary for the proposal the new antiviral strategies. This review brings to view the members of Potyviridae family with respect to plum pox virus. The genome of potyviruses is discussed with respect to protein products of its expression and their function. Plum pox virus distribution, genome organization, transmission and biochemical changes in infected plants are introduced. In addition, techniques used in PPV detection are accentuated and discussed, especially with respect to new modern techniques of nucleic acids isolation, based on the nanotechnological approach. Finally, perspectives on the future of possibilities for nanotechnology application in PPV determination/identification are outlined. Full article
(This article belongs to the Special Issue Plant Viruses)
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Open AccessReview The Role of Severe Acute Respiratory Syndrome (SARS)-Coronavirus Accessory Proteins in Virus Pathogenesis
Viruses 2012, 4(11), 2902-2923; doi:10.3390/v4112902
Received: 1 October 2012 / Revised: 2 November 2012 / Accepted: 5 November 2012 / Published: 7 November 2012
Cited by 15 | PDF Full-text (465 KB) | HTML Full-text | XML Full-text
Abstract
A respiratory disease caused by a novel coronavirus, termed the severe acute respiratory syndrome coronavirus (SARS-CoV), was first reported in China in late 2002. The subsequent efficient human-to-human transmission of this virus eventually affected more than 30 countries worldwide, resulting in a [...] Read more.
A respiratory disease caused by a novel coronavirus, termed the severe acute respiratory syndrome coronavirus (SARS-CoV), was first reported in China in late 2002. The subsequent efficient human-to-human transmission of this virus eventually affected more than 30 countries worldwide, resulting in a mortality rate of ~10% of infected individuals. The spread of the virus was ultimately controlled by isolation of infected individuals and there has been no infections reported since April 2004. However, the natural reservoir of the virus was never identified and it is not known if this virus will re-emerge and, therefore, research on this virus continues. The SARS-CoV genome is about 30 kb in length and is predicted to contain 14 functional open reading frames (ORFs). The genome encodes for proteins that are homologous to known coronavirus proteins, such as the replicase proteins (ORFs 1a and 1b) and the four major structural proteins: nucleocapsid (N), spike (S), membrane (M) and envelope (E). SARS-CoV also encodes for eight unique proteins, called accessory proteins, with no known homologues. This review will summarize the current knowledge on SARS-CoV accessory proteins and will include: (i) expression and processing; (ii) the effects on cellular processes; and (iii) functional studies. Full article
(This article belongs to the Special Issue Perspectives and Challenges in Coronavirus Research)
Open AccessReview Molecular Signatures of Hepatitis C Virus (HCV)-Induced Type II Mixed Cryoglobulinemia (MCII)
Viruses 2012, 4(11), 2924-2944; doi:10.3390/v4112924
Received: 1 October 2012 / Revised: 29 October 2012 / Accepted: 5 November 2012 / Published: 8 November 2012
Cited by 7 | PDF Full-text (457 KB) | HTML Full-text | XML Full-text
Abstract
The role of hepatitis C virus (HCV) infection in the induction of type II mixed cryoglobulinemia (MCII) and the possible establishment of related lymphoproliferative disorders, such as B-cell non-Hodgkin lymphoma (B-NHL), is well ascertained. However, the molecular pathways involved and the factors [...] Read more.
The role of hepatitis C virus (HCV) infection in the induction of type II mixed cryoglobulinemia (MCII) and the possible establishment of related lymphoproliferative disorders, such as B-cell non-Hodgkin lymphoma (B-NHL), is well ascertained. However, the molecular pathways involved and the factors predisposing to the development of these HCV-related extrahepatic complications deserve further consideration and clarification. To date, several host- and virus-related factors have been implicated in the progression to MCII, such as the virus-induced expansion of selected subsets of B-cell clones expressing discrete immunoglobulin variable (IgV) gene subfamilies, the involvement of complement factors and the specific role of some HCV proteins. In this review, we will analyze the host and viral factors taking part in the development of MCII in order to give a general outlook of the molecular mechanisms implicated. Full article
(This article belongs to the Special Issue Hepatitis C Pathology)
Open AccessReview Modulation of Apoptotic Signaling by the Hepatitis B Virus X Protein
Viruses 2012, 4(11), 2945-2972; doi:10.3390/v4112945
Received: 5 September 2012 / Revised: 23 October 2012 / Accepted: 31 October 2012 / Published: 8 November 2012
Cited by 26 | PDF Full-text (764 KB) | HTML Full-text | XML Full-text
Abstract
Worldwide, an estimated 350 million people are chronically infected with the Hepatitis B Virus (HBV); chronic infection with HBV is associated with the development of severe liver diseases including hepatitis and cirrhosis. Individuals who are chronically infected with HBV also have a [...] Read more.
Worldwide, an estimated 350 million people are chronically infected with the Hepatitis B Virus (HBV); chronic infection with HBV is associated with the development of severe liver diseases including hepatitis and cirrhosis. Individuals who are chronically infected with HBV also have a significantly higher risk of developing hepatocellular carcinoma (HCC) than uninfected individuals. The HBV X protein (HBx) is a key regulatory HBV protein that is important for HBV replication, and likely plays a cofactor role in the development of HCC in chronically HBV-infected individuals. Although some of the functions of HBx that may contribute to the development of HCC have been characterized, many HBx activities, and their putative roles during the development of HBV-associated HCC, remain incompletely understood. HBx is a multifunctional protein that localizes to the cytoplasm, nucleus, and mitochondria of HBV‑infected hepatocytes. HBx regulates numerous cellular signal transduction pathways and transcription factors as well as cell cycle progression and apoptosis. In this review, we will summarize reports in which the impact of HBx expression on cellular apoptotic pathways has been analyzed. Although various effects of HBx on apoptotic pathways have been observed in different model systems, studies of HBx activities in biologically relevant hepatocyte systems have begun to clarify apoptotic effects of HBx and suggest mechanisms that could link HBx modulation of apoptotic pathways to the development of HBV-associated HCC. Full article
(This article belongs to the Special Issue Modulation of Apoptosis by Viral Infection)
Open AccessReview Multifunctional Nature of the Arenavirus RING Finger Protein Z
Viruses 2012, 4(11), 2973-3011; doi:10.3390/v4112973
Received: 4 October 2012 / Revised: 4 November 2012 / Accepted: 5 November 2012 / Published: 9 November 2012
Cited by 13 | PDF Full-text (2571 KB) | HTML Full-text | XML Full-text
Abstract
Arenaviruses are a family of enveloped negative-stranded RNA viruses that can cause severe human disease ranging from encephalitis symptoms to fulminant hemorrhagic fever. The bi‑segmented RNA genome encodes four polypeptides: the nucleoprotein NP, the surface glycoprotein GP, the polymerase L, and the [...] Read more.
Arenaviruses are a family of enveloped negative-stranded RNA viruses that can cause severe human disease ranging from encephalitis symptoms to fulminant hemorrhagic fever. The bi‑segmented RNA genome encodes four polypeptides: the nucleoprotein NP, the surface glycoprotein GP, the polymerase L, and the RING finger protein Z. Although it is the smallest arenavirus protein with a length of 90 to 99 amino acids and a molecular weight of approx. 11 kDa, the Z protein has multiple functions in the viral life cycle including (i) regulation of viral RNA synthesis, (ii) orchestration of viral assembly and budding, (iii) interaction with host cell proteins, and (iv) interferon antagonism. In this review, we summarize our current understanding of the structural and functional role of the Z protein in the arenavirus replication cycle. Full article
(This article belongs to the Special Issue Arenaviruses)
Open AccessReview HIV-1 Induced Bystander Apoptosis
Viruses 2012, 4(11), 3020-3043; doi:10.3390/v4113020
Received: 7 September 2012 / Revised: 19 October 2012 / Accepted: 2 November 2012 / Published: 9 November 2012
Cited by 18 | PDF Full-text (447 KB) | HTML Full-text | XML Full-text
Abstract
Apoptosis of uninfected bystander cells is a key element of HIV pathogenesis and believed to be the driving force behind the selective depletion of CD4+ T cells leading to immunodeficiency. While several viral proteins have been implicated in this process the complex [...] Read more.
Apoptosis of uninfected bystander cells is a key element of HIV pathogenesis and believed to be the driving force behind the selective depletion of CD4+ T cells leading to immunodeficiency. While several viral proteins have been implicated in this process the complex interaction between Env glycoprotein expressed on the surface of infected cells and the receptor and co-receptor expressing bystander cells has been proposed as a major mechanism. HIV-1 utilizes CD4 as the primary receptor for entry into cells; however, it is the viral co-receptor usage that greatly influences CD4 decline and progression to AIDS. This phenomenon is relatively simple for X4 viruses, which arise later during the course of the disease, are considered to be highly fusogenic, and cause a rapid CD4+ T cell decline. However, in contrast, R5 viruses in general have a greater transmissibility, are encountered early during the disease and have a lesser pathogenic potential than the former. The above generalization gets complicated in numerous situations where R5 viruses persist throughout the disease and are capable of causing a rigorous CD4+ T cell decline. This review will discuss the multiple factors that are reported to influence HIV induced bystander apoptosis and pathogenesis including Env glycoprotein phenotype, virus tropism, disease stage, co-receptor expression on CD4+ T cells, immune activation and therapies targeting the viral envelope. Full article
(This article belongs to the Special Issue Modulation of Apoptosis by Viral Infection)
Open AccessReview Human Coronaviruses: Insights into Environmental Resistance and Its Influence on the Development of New Antiseptic Strategies
Viruses 2012, 4(11), 3044-3068; doi:10.3390/v4113044
Received: 5 October 2012 / Revised: 31 October 2012 / Accepted: 2 November 2012 / Published: 12 November 2012
Cited by 12 | PDF Full-text (438 KB) | HTML Full-text | XML Full-text
Abstract
The Coronaviridae family, an enveloped RNA virus family, and, more particularly, human coronaviruses (HCoV), were historically known to be responsible for a large portion of common colds and other upper respiratory tract infections. HCoV are now known to be involved in more [...] Read more.
The Coronaviridae family, an enveloped RNA virus family, and, more particularly, human coronaviruses (HCoV), were historically known to be responsible for a large portion of common colds and other upper respiratory tract infections. HCoV are now known to be involved in more serious respiratory diseases, i.e. bronchitis, bronchiolitis or pneumonia, especially in young children and neonates, elderly people and immunosuppressed patients. They have also been involved in nosocomial viral infections. In 2002–2003, the outbreak of severe acute respiratory syndrome (SARS), due to a newly discovered coronavirus, the SARS-associated coronavirus (SARS-CoV); led to a new awareness of the medical importance of the Coronaviridae family. This pathogen, responsible for an emerging disease in humans, with high risk of fatal outcome; underline the pressing need for new approaches to the management of the infection, and primarily to its prevention. Another interesting feature of coronaviruses is their potential environmental resistance, despite the accepted fragility of enveloped viruses. Indeed, several studies have described the ability of HCoVs (i.e. HCoV 229E, HCoV OC43 (also known as betacoronavirus 1), NL63, HKU1 or SARS-CoV) to survive in different environmental conditions (e.g. temperature and humidity), on different supports found in hospital settings such as aluminum, sterile sponges or latex surgical gloves or in biological fluids. Finally, taking into account the persisting lack of specific antiviral treatments (there is, in fact, no specific treatment available to fight coronaviruses infections), the Coronaviridae specificities (i.e. pathogenicity, potential environmental resistance) make them a challenging model for the development of efficient means of prevention, as an adapted antisepsis-disinfection, to prevent the environmental spread of such infective agents. This review will summarize current knowledge on the capacity of human coronaviruses to survive in the environment and the efficacy of well-known antiseptic-disinfectants against them, with particular focus on the development of new methodologies to evaluate the activity of new antiseptic-disinfectants on viruses. Full article
(This article belongs to the Special Issue Perspectives and Challenges in Coronavirus Research)
Open AccessReview Influenza B-Cells Protective Epitope Characterization: A Passkey for the Rational Design of New Broad-Range Anti-Influenza Vaccines
Viruses 2012, 4(11), 3090-3108; doi:10.3390/v4113090
Received: 28 September 2012 / Revised: 5 November 2012 / Accepted: 7 November 2012 / Published: 14 November 2012
Cited by 6 | PDF Full-text (3810 KB) | HTML Full-text | XML Full-text
Abstract
The emergence of new influenza strains causing pandemics represents a serious threat to human health. From 1918, four influenza pandemics occurred, caused by H1N1, H2N2 and H3N2 subtypes. Moreover, in 1997 a novel influenza avian strain belonging to the H5N1 subtype infected [...] Read more.
The emergence of new influenza strains causing pandemics represents a serious threat to human health. From 1918, four influenza pandemics occurred, caused by H1N1, H2N2 and H3N2 subtypes. Moreover, in 1997 a novel influenza avian strain belonging to the H5N1 subtype infected humans. Nowadays, even if its transmission is still circumscribed to avian species, the capability of the virus to infect humans directly from avian reservoirs can result in fatalities. Moreover, the risk that this or novel avian strains could adapt to inter-human transmission, the development of resistance to anti-viral drugs and the lack of an effective prevention are all incumbent problems for the world population. In this scenario, the identification of broadly neutralizing monoclonal antibodies (mAbs) directed against conserved regions shared among influenza isolates has raised hopes for the development of monoclonal antibody-based immunotherapy and “universal” anti-influenza vaccines. Full article
Open AccessReview Cellular Prion Protein: From Physiology to Pathology
Viruses 2012, 4(11), 3109-3131; doi:10.3390/v4113109
Received: 30 September 2012 / Revised: 5 November 2012 / Accepted: 6 November 2012 / Published: 14 November 2012
Cited by 10 | PDF Full-text (745 KB) | HTML Full-text | XML Full-text
Abstract
The human cellular prion protein (PrPC) is a glycosylphosphatidylinositol (GPI) anchored membrane glycoprotein with two N-glycosylation sites at residues 181 and 197. This protein migrates in several bands by Western blot analysis (WB). Interestingly, PNGase F treatment of human brain [...] Read more.
The human cellular prion protein (PrPC) is a glycosylphosphatidylinositol (GPI) anchored membrane glycoprotein with two N-glycosylation sites at residues 181 and 197. This protein migrates in several bands by Western blot analysis (WB). Interestingly, PNGase F treatment of human brain homogenates prior to the WB, which is known to remove the N-glycosylations, unexpectedly gives rise to two dominant bands, which are now known as C-terminal (C1) and N-terminal (N1) fragments. This resembles the β-amyloid precursor protein (APP) in Alzheimer disease (AD), which can be physiologically processed by α-, β-, and γ-secretases. The processing of APP has been extensively studied, while the identity of the cellular proteases involved in the proteolysis of PrPC and their possible role in prion biology has remained limited and controversial. Nevertheless, there is a strong correlation between the neurotoxicity caused by prion proteins and the blockade of their normal proteolysis. For example, expression of non-cleavable PrPC mutants in transgenic mice generates neurotoxicity, even in the absence of infectious prions, suggesting that PrPC proteolysis is physiologically and pathologically important. As many mouse models of prion diseases have recently been developed and the knowledge about the proteases responsible for the PrPC proteolysis is accumulating, we examine the historical experimental evidence and highlight recent studies that shed new light on this issue. Full article
(This article belongs to the Special Issue Recent Developments in the Prion Field)
Open AccessReview Running Loose or Getting Lost: How HIV-1 Counters and Capitalizes on APOBEC3-Induced Mutagenesis through Its Vif Protein
Viruses 2012, 4(11), 3132-3161; doi:10.3390/v4113132
Received: 25 September 2012 / Revised: 29 October 2012 / Accepted: 5 November 2012 / Published: 14 November 2012
Cited by 12 | PDF Full-text (1690 KB) | HTML Full-text | XML Full-text
Abstract
Human immunodeficiency virus-1 (HIV-1) dynamics reflect an intricate balance within the viruses’ host. The virus relies on host replication factors, but must escape or counter its host’s antiviral restriction factors. The interaction between the HIV-1 protein Vif and many cellular restriction factors [...] Read more.
Human immunodeficiency virus-1 (HIV-1) dynamics reflect an intricate balance within the viruses’ host. The virus relies on host replication factors, but must escape or counter its host’s antiviral restriction factors. The interaction between the HIV-1 protein Vif and many cellular restriction factors from the APOBEC3 protein family is a prominent example of this evolutionary arms race. The viral infectivity factor (Vif) protein largely neutralizes APOBEC3 proteins, which can induce in vivo hypermutations in HIV-1 to the extent of lethal mutagenesis, and ensures the production of viable virus particles. HIV-1 also uses the APOBEC3-Vif interaction to modulate its own mutation rate in harsh or variable environments, and it is a model of adaptation in a coevolutionary setting. Both experimental evidence and the substantiation of the underlying dynamics through coevolutionary models are presented as complementary views of a coevolutionary arms race. Full article
(This article belongs to the Special Issue HIV Dynamics and Evolution)
Open AccessReview Interaction of Bacteriophage l with Its E. coli Receptor, LamB
Viruses 2012, 4(11), 3162-3178; doi:10.3390/v4113162
Received: 5 October 2012 / Revised: 17 October 2012 / Accepted: 27 October 2012 / Published: 15 November 2012
Cited by 23 | PDF Full-text (2344 KB) | HTML Full-text | XML Full-text
Abstract
The initial step of viral infection is the binding of a virus onto the host cell surface. This first viral-host interaction would determine subsequent infection steps and the fate of the entire infection process. A basic understating of the underlining mechanism of [...] Read more.
The initial step of viral infection is the binding of a virus onto the host cell surface. This first viral-host interaction would determine subsequent infection steps and the fate of the entire infection process. A basic understating of the underlining mechanism of initial virus-host binding is a prerequisite for establishing the nature of viral infection. Bacteriophage λ and its host Escherichia coli serve as an excellent paradigm for this purpose. λ phages bind to specific receptors, LamB, on the host cell surface during the infection process. The interaction of bacteriophage λ with the LamB receptor has been the topic of many studies, resulting in wealth of information on the structure, biochemical properties and molecular biology of this system. Recently, imaging studies using fluorescently labeled phages and its receptor unveil the role of spatiotemporal dynamics and divulge the importance of stochasticity from hidden variables in the infection outcomes. The scope of this article is to review the present state of research on the interaction of bacteriophage λ and its E. coli receptor, LamB. Full article
(This article belongs to the Special Issue Recent Progress in Bacteriophage Research) Print Edition available
Open AccessReview Insight into Alternative Approaches for Control of Avian Influenza in Poultry, with Emphasis on Highly Pathogenic H5N1
Viruses 2012, 4(11), 3179-3208; doi:10.3390/v4113179
Received: 23 September 2012 / Revised: 4 November 2012 / Accepted: 8 November 2012 / Published: 19 November 2012
Cited by 8 | PDF Full-text (407 KB) | HTML Full-text | XML Full-text
Abstract
Highly pathogenic avian influenza virus (HPAIV) of subtype H5N1 causes a devastating disease in poultry but when it accidentally infects humans it can cause death. Therefore, decrease the incidence of H5N1 in humans needs to focus on prevention and control of poultry [...] Read more.
Highly pathogenic avian influenza virus (HPAIV) of subtype H5N1 causes a devastating disease in poultry but when it accidentally infects humans it can cause death. Therefore, decrease the incidence of H5N1 in humans needs to focus on prevention and control of poultry infections. Conventional control strategies in poultry based on surveillance, stamping out, movement restriction and enforcement of biosecurity measures did not prevent the virus spreading, particularly in developing countries. Several challenges limit efficiency of the vaccines to prevent outbreaks of HPAIV H5N1 in endemic countries. Alternative and complementary approaches to reduce the current burden of H5N1 epidemics in poultry should be encouraged. The use of antiviral chemotherapy and natural compounds, avian-cytokines, RNA interference, genetic breeding and/or development of transgenic poultry warrant further evaluation as integrated intervention strategies for control of HPAIV H5N1 in poultry. Full article
(This article belongs to the Special Issue H5N1 Influenza Virus)
Open AccessReview Biogenesis and Dynamics of the Coronavirus Replicative Structures
Viruses 2012, 4(11), 3245-3269; doi:10.3390/v4113245
Received: 21 October 2012 / Revised: 14 November 2012 / Accepted: 15 November 2012 / Published: 21 November 2012
Cited by 13 | PDF Full-text (890 KB) | HTML Full-text | XML Full-text
Abstract
Coronaviruses are positive-strand RNA viruses that are important infectious agents of both animals and humans. A common feature among positive-strand RNA viruses is their assembly of replication-transcription complexes in association with cytoplasmic membranes. Upon infection, coronaviruses extensively rearrange cellular membranes into organelle-like [...] Read more.
Coronaviruses are positive-strand RNA viruses that are important infectious agents of both animals and humans. A common feature among positive-strand RNA viruses is their assembly of replication-transcription complexes in association with cytoplasmic membranes. Upon infection, coronaviruses extensively rearrange cellular membranes into organelle-like replicative structures that consist of double-membrane vesicles and convoluted membranes to which the nonstructural proteins involved in RNA synthesis localize. Double-stranded RNA, presumably functioning as replicative intermediate during viral RNA synthesis, has been detected at the double-membrane vesicle interior. Recent studies have provided new insights into the assembly and functioning of the coronavirus replicative structures. This review will summarize the current knowledge on the biogenesis of the replicative structures, the membrane anchoring of the replication-transcription complexes, and the location of viral RNA synthesis, with particular focus on the dynamics of the coronavirus replicative structures and individual replication-associated proteins. Full article
(This article belongs to the Special Issue Perspectives and Challenges in Coronavirus Research)

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