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Viruses, Volume 5, Issue 8 (August 2013), Pages 1901-2061

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Research

Jump to: Review

Open AccessArticle Sialic Acid Binding Properties of Soluble Coronavirus Spike (S1) Proteins: Differences between Infectious Bronchitis Virus and Transmissible Gastroenteritis Virus
Viruses 2013, 5(8), 1924-1933; doi:10.3390/v5081924
Received: 14 June 2013 / Revised: 8 July 2013 / Accepted: 23 July 2013 / Published: 26 July 2013
Cited by 10 | PDF Full-text (423 KB) | HTML Full-text | XML Full-text
Abstract
The spike proteins of a number of coronaviruses are able to bind to sialic acids present on the cell surface. The importance of this sialic acid binding ability during infection is, however, quite different. We compared the spike protein of transmissible gastroenteritis virus
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The spike proteins of a number of coronaviruses are able to bind to sialic acids present on the cell surface. The importance of this sialic acid binding ability during infection is, however, quite different. We compared the spike protein of transmissible gastroenteritis virus (TGEV) and the spike protein of infectious bronchitis virus (IBV). Whereas sialic acid is the only receptor determinant known so far for IBV, TGEV requires interaction with its receptor aminopeptidase N to initiate infection of cells. Binding tests with soluble spike proteins carrying an IgG Fc-tag revealed pronounced differences between these two viral proteins. Binding of the IBV spike protein to host cells was in all experiments sialic acid dependent, whereas the soluble TGEV spike showed binding to APN but had no detectable sialic acid binding activity. Our results underline the different ways in which binding to sialoglycoconjugates is mediated by coronavirus spike proteins. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
Open AccessArticle Avian Influenza: Mixed Infections and Missing Viruses
Viruses 2013, 5(8), 1964-1977; doi:10.3390/v5081964
Received: 7 June 2013 / Revised: 20 July 2013 / Accepted: 23 July 2013 / Published: 5 August 2013
Cited by 4 | PDF Full-text (227 KB) | HTML Full-text | XML Full-text
Abstract
A high prevalence and diversity of avian influenza (AI) viruses were detected in a population of wild mallards sampled during summer 2011 in California, providing an opportunity to compare results obtained before and after virus culture. We tested cloacal swab samples prior to
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A high prevalence and diversity of avian influenza (AI) viruses were detected in a population of wild mallards sampled during summer 2011 in California, providing an opportunity to compare results obtained before and after virus culture. We tested cloacal swab samples prior to culture by matrix real-time PCR, and by amplifying and sequencing a 640bp portion of the hemagglutinin (HA) gene. Each sample was also inoculated into embryonated chicken eggs, and full genome sequences were determined for cultured viruses. While low matrix Ct values were a good predictor of virus isolation from eggs, samples with high or undetectable Ct values also yielded isolates. Furthermore, a single passage in eggs altered the occurrence and detection of viral strains, and mixed infections (different HA subtypes) were detected less frequently after culture. There is no gold standard or perfect reference comparison for surveillance of unknown viruses, and true negatives are difficult to distinguish from false negatives. This study showed that sequencing samples prior to culture increases the detection of mixed infections and enhances the identification of viral strains and sequences that may have changed or even disappeared during culture. Full article
(This article belongs to the Section Animal Viruses)
Open AccessArticle Molecular Characterization and Phylogenetic Analysis of New Variants of the Porcine Epidemic Diarrhea Virus in Gansu, China in 2012
Viruses 2013, 5(8), 1991-2004; doi:10.3390/v5081991
Received: 17 June 2013 / Revised: 24 July 2013 / Accepted: 1 August 2013 / Published: 15 August 2013
Cited by 16 | PDF Full-text (24799 KB) | HTML Full-text | XML Full-text
Abstract
Between January 2012 and March 2012, the infection rates of porcine epidemic diarrhea virus (PEDV) increased substantially in vaccinated swine herds in many porcine farms in Gansu Province, China. The spike (S) glycoprotein is an important determinant for PEDV biological properties. To determine
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Between January 2012 and March 2012, the infection rates of porcine epidemic diarrhea virus (PEDV) increased substantially in vaccinated swine herds in many porcine farms in Gansu Province, China. The spike (S) glycoprotein is an important determinant for PEDV biological properties. To determine the distribution profile of PEDV outbreak strains, we sequenced the full-length S gene of five samples from two farms where animals exhibited severe diarrhea and high mortality rates. Five new PEDV variants were identified, and the molecular diversity, phylogenetic relationships, and antigenicity analysis of Gansu field samples with other PEDV reference strains were investigated. A series of insertions, deletions, and mutations in the S gene was found in five PEDV variants compared with classical and vaccine strains. These mutations may provide stronger pathogenicity and antigenicity to the new PEDV variants that influenced the effectiveness of the CV777-based vaccine. Our results suggest that these new PEDV variant strains in Gansu Province might be from South Korean or South China, and the effectiveness of the CV777-based vaccine needs to be evaluated. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
Open AccessArticle A Polytropic Caprine Arthritis Encephalitis Virus Promoter Isolated from Multiple Tissues from a Sheep with Multisystemic Lentivirus-Associated Inflammatory Disease
Viruses 2013, 5(8), 2005-2018; doi:10.3390/v5082005
Received: 5 July 2013 / Revised: 3 August 2013 / Accepted: 12 August 2013 / Published: 15 August 2013
Cited by 1 | PDF Full-text (6180 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Caprine arthritis encephalitis virus (CAEV) is a lentivirus that infects both goats and sheep and is closely related to maedi-visna virus that infects sheep; collectively, these viruses are known as small ruminant lentiviruses (SRLV). Infection of goats and sheep with SRLV typically results
[...] Read more.
Caprine arthritis encephalitis virus (CAEV) is a lentivirus that infects both goats and sheep and is closely related to maedi-visna virus that infects sheep; collectively, these viruses are known as small ruminant lentiviruses (SRLV). Infection of goats and sheep with SRLV typically results in discrete inflammatory diseases which include arthritis, mastitis, pneumonia or encephalomyelitis. SRLV-infected animals concurrently demonstrating lentivirus-associated lesions in tissues of lung, mammary gland, joint synovium and the central nervous system are either very rare or have not been reported. Here we describe a novel CAEV promoter isolated from a sheep with multisystemic lentivirus-associated inflammatory disease including interstitial pneumonia, mastitis, polyarthritis and leukomyelitis. A single, novel SRLV promoter was cloned and sequenced from five different anatomical locations (brain stem, spinal cord, lung, mammary gland and carpal joint synovium), all of which demonstrated lesions characteristic of lentivirus associated inflammation. This SRLV promoter isolate was found to be closely related to CAEV promoters isolated from goats in northern California and other parts of the world. The promoter was denoted CAEV-ovine-MS (multisystemic disease); the stability of the transcription factor binding sites within the U3 promoter sequence are discussed. Full article
(This article belongs to the Special Issue Small Ruminant Lentiviruses)

Review

Jump to: Research

Open AccessReview Kaposi’s Sarcoma-Associated Herpesvirus ORF57 Protein: Exploiting All Stages of Viral mRNA Processing
Viruses 2013, 5(8), 1901-1923; doi:10.3390/v5081901
Received: 18 June 2013 / Revised: 16 July 2013 / Accepted: 19 July 2013 / Published: 26 July 2013
Cited by 12 | PDF Full-text (1111 KB) | HTML Full-text | XML Full-text
Abstract
Nuclear mRNA export is a highly complex and regulated process in cells. Cellular transcripts must undergo successful maturation processes, including splicing, 5'-, and 3'-end processing, which are essential for assembly of an export competent ribonucleoprotein particle. Many viruses replicate in the nucleus of
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Nuclear mRNA export is a highly complex and regulated process in cells. Cellular transcripts must undergo successful maturation processes, including splicing, 5'-, and 3'-end processing, which are essential for assembly of an export competent ribonucleoprotein particle. Many viruses replicate in the nucleus of the host cell and require cellular mRNA export factors to efficiently export viral transcripts. However, some viral mRNAs undergo aberrant mRNA processing, thus prompting the viruses to express their own specific mRNA export proteins to facilitate efficient export of viral transcripts and allowing translation in the cytoplasm. This review will focus on the Kaposi’s sarcoma-associated herpesvirus ORF57 protein, a multifunctional protein involved in all stages of viral mRNA processing and that is essential for virus replication. Using the example of ORF57, we will describe cellular bulk mRNA export pathways and highlight their distinct features, before exploring how the virus has evolved to exploit these mechanisms. Full article
(This article belongs to the Special Issue Viral Nuclear Import)
Open AccessReview Host Restriction of Lentiviruses and Viral Countermeasures: APOBEC3 and Vif
Viruses 2013, 5(8), 1934-1947; doi:10.3390/v5081934
Received: 20 June 2013 / Revised: 19 July 2013 / Accepted: 19 July 2013 / Published: 30 July 2013
Cited by 1 | PDF Full-text (6474 KB) | HTML Full-text | XML Full-text
Abstract
It is becoming increasingly clear that organisms have developed a variety of mechanisms to fight against viral infection. The viruses have developed means of counteracting these defences in various ways. The APOBEC3 proteins are a mammalian-specific family of nucleic acid cytidine deaminases that
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It is becoming increasingly clear that organisms have developed a variety of mechanisms to fight against viral infection. The viruses have developed means of counteracting these defences in various ways. The APOBEC3 proteins are a mammalian-specific family of nucleic acid cytidine deaminases that block retroviral infection. These inhibitors are counteracted by the Vif proteins encoded by most lentiviruses. In this paper, we will review the interaction of the lentiviral Vif proteins with the APOBEC3 proteins, with an emphasis on sheep APOBEC3 and maedi-visna virus (MVV) Vif. Full article
(This article belongs to the Special Issue Small Ruminant Lentiviruses)
Open AccessReview Immunization against Small Ruminant Lentiviruses
Viruses 2013, 5(8), 1948-1963; doi:10.3390/v5081948
Received: 14 June 2013 / Revised: 24 July 2013 / Accepted: 25 July 2013 / Published: 2 August 2013
Cited by 2 | PDF Full-text (203 KB) | HTML Full-text | XML Full-text
Abstract
Multisystemic disease caused by Small Ruminant Lentiviruses (SRLV) in sheep and goats leads to production losses, to the detriment of animal health and welfare. This, together with the lack of treatments, has triggered interest in exploring different strategies of immunization to control the
[...] Read more.
Multisystemic disease caused by Small Ruminant Lentiviruses (SRLV) in sheep and goats leads to production losses, to the detriment of animal health and welfare. This, together with the lack of treatments, has triggered interest in exploring different strategies of immunization to control the widely spread SRLV infection and, also, to provide a useful model for HIV vaccines. These strategies involve inactivated whole virus, subunit vaccines, DNA encoding viral proteins in the presence or absence of plasmids encoding immunological adjuvants and naturally or artificially attenuated viruses. In this review, we revisit, comprehensively, the immunization strategies against SRLV and analyze this double edged tool individually, as it may contribute to either controlling or enhancing virus replication and/or disease. Full article
(This article belongs to the Special Issue Small Ruminant Lentiviruses)
Open AccessReview Nucleocytoplasmic Shuttling of Viral Proteins in Borna Disease Virus Infection
Viruses 2013, 5(8), 1978-1990; doi:10.3390/v5081978
Received: 18 June 2013 / Revised: 2 August 2013 / Accepted: 5 August 2013 / Published: 8 August 2013
Cited by 6 | PDF Full-text (2161 KB) | HTML Full-text | XML Full-text
Abstract
Nuclear import and export of viral RNA and proteins are critical to the replication cycle of viruses that replicate in the nucleus. Borna disease virus (BDV) is a nonsegmented, negative-strand RNA virus that belongs to the order Mononegavirales. BDV has several distinguishing
[...] Read more.
Nuclear import and export of viral RNA and proteins are critical to the replication cycle of viruses that replicate in the nucleus. Borna disease virus (BDV) is a nonsegmented, negative-strand RNA virus that belongs to the order Mononegavirales. BDV has several distinguishing features, one of the most striking being the site of its replication. BDV RNA is transcribed and replicated in the nucleus, while most other negative-strand RNA viruses replicate in the cytoplasm. Therefore, the nucleocytoplasmic trafficking of BDV macromolecules plays a key role in virus replication. Growing evidence indicates that several BDV proteins, including the nucleoprotein, phosphoprotein, protein X and large protein, contribute to the nucleocytoplasmic trafficking of BDV ribonucleoprotein (RNP). The directional control of BDV RNP trafficking is likely determined by the ratios of and interactions between the nuclear localization signals and nuclear export signals in the RNP. In this review, we present a comprehensive view of several unique mechanisms that BDV has developed to control its RNP trafficking and discuss the significance of BDV RNP trafficking in the replication cycle of BDV. Full article
(This article belongs to the Special Issue Viral Nuclear Import)
Open AccessReview Viral Subversion of the Nuclear Pore Complex
Viruses 2013, 5(8), 2019-2042; doi:10.3390/v5082019
Received: 3 June 2013 / Revised: 29 July 2013 / Accepted: 8 August 2013 / Published: 16 August 2013
Cited by 17 | PDF Full-text (395 KB) | HTML Full-text | XML Full-text
Abstract
The nuclear pore complex (NPC) acts as a selective barrier between the nucleus and the cytoplasm and is responsible for mediating communication by regulating the transport of RNA and proteins. Numerous viral pathogens have evolved different mechanisms to hijack the NPC in order
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The nuclear pore complex (NPC) acts as a selective barrier between the nucleus and the cytoplasm and is responsible for mediating communication by regulating the transport of RNA and proteins. Numerous viral pathogens have evolved different mechanisms to hijack the NPC in order to regulate trafficking of viral proteins, genomes and even capsids into and out of the nucleus thus promoting virus replication. The present review examines the different strategies and the specific nucleoporins utilized during viral infections as a means of promoting their life cycle and inhibiting host viral defenses. Full article
(This article belongs to the Special Issue Viral Nuclear Import)
Open AccessReview Retroviral Infections in Sheep and Goats: Small Ruminant Lentiviruses and Host Interaction
Viruses 2013, 5(8), 2043-2061; doi:10.3390/v5082043
Received: 3 June 2013 / Revised: 26 July 2013 / Accepted: 5 August 2013 / Published: 19 August 2013
Cited by 7 | PDF Full-text (1767 KB) | HTML Full-text | XML Full-text
Abstract
Small ruminant lentiviruses (SRLV) are members of the Retrovirus family comprising the closely related Visna/Maedi Virus (VMV) and the Caprine Arthritis-Encephalitis Virus (CAEV), which infect sheep and goats. Both infect cells of the monocyte/macrophage lineage and cause lifelong infections. Infection by VMV and
[...] Read more.
Small ruminant lentiviruses (SRLV) are members of the Retrovirus family comprising the closely related Visna/Maedi Virus (VMV) and the Caprine Arthritis-Encephalitis Virus (CAEV), which infect sheep and goats. Both infect cells of the monocyte/macrophage lineage and cause lifelong infections. Infection by VMV and CAEV can lead to Visna/Maedi (VM) and Caprine Arthritis-Encephalitis (CAE) respectively, slow progressive inflammatory diseases primarily affecting the lungs, nervous system, joints and mammary glands. VM and CAE are distributed worldwide and develop over a period of months or years, always leading to the death of the host, with the consequent economic and welfare implications. Currently, the control of VM and CAE relies on the control of transmission and culling of infected animals. However, there is evidence that host genetics play an important role in determining Susceptibility/Resistance to SRLV infection and disease progression, but little work has been performed in small ruminants. More research is necessary to understand the host-SRLV interaction. Full article
(This article belongs to the Special Issue Small Ruminant Lentiviruses)

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