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Special Issue "Animal Arteriviruses and Coronaviruses"

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A special issue of Viruses (ISSN 1999-4915). This special issue belongs to the section "Animal Viruses".

Deadline for manuscript submissions: closed (30 November 2013)

Special Issue Editor

Guest Editor
Dr. Xiuqing Wang

Department of Biology and Microbiology, Center for Infectious Disease Research and Vaccinology, South Dakota State University, SNP 252D, Box 2140D, Brookings, SD 57007, USA
Website | E-Mail
Interests: arteriviruses; porcine reproductive and respiratory syndrome virus (PRRSV); coronaviruses; infectious bronchitis virus (IBV); viral immunity; viral pathogenesis; viral vectors; virus-cell interactions; moncyte-derived dendritic cells

Special Issue Information

Dear Colleagues,

Animal arteriviruses and coronaviruses, such as porcine reproductive and respiratory syndrome virus (PRRSV) and chicken infectious bronchitis virus (IBV), cause significant economic losses to the animal industry. PRRSV primarily infects macrophages and dendritic cells, which serve as an ideal model system to study host-pathogen interactions, especially the immune evasion mechanisms. Interestingly, IBV, a prototype of coronavirus, causes polyclonal activation of leukocytes in animals. Porcine respiratory coronavirus, on the other hand, has been used as a model system to better understand the pathogenesis of Severe Acute Respiratory Syndrome (SARS) virus in humans. Equine arteritis virus and bovine coronavirus are also important pathogens that cause severe diseases in their respective host species.

This special issue of “ Viruses” focuses on broad aspects of animal arteriviruses and coronaviruses, which include, but are not limited to, virus replication and assembly, virus-host interactions, role of viral structural and nonstructural proteins in viral pathogenesis and immunity, and their potential applications in vaccine development.

Dr. Xiuqing Wang
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Viruses is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs).

Keywords

  • arteriviruses
  • coronaviruses
  • replication and assembly
  • pathogenesis
  • innate immunity
  • immune evasion
  • vaccines

Published Papers (17 papers)

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Research

Jump to: Review, Other

Open AccessArticle Molecular Characterizations of Subcellular Localization Signals in the Nucleocapsid Protein of Porcine Epidemic Diarrhea Virus
Viruses 2014, 6(3), 1253-1273; doi:10.3390/v6031253
Received: 26 November 2013 / Revised: 24 February 2014 / Accepted: 5 March 2014 / Published: 13 March 2014
Cited by 4 | PDF Full-text (2127 KB) | HTML Full-text | XML Full-text
Abstract
The nucleolus is a dynamic subnuclear structure, which is crucial to the normal operation of the eukaryotic cell. The porcine epidemic diarrhea virus (PEDV), coronavirus nucleocapsid (N) protein, plays important roles in the process of virus replication and cellular infection. Virus infection and
[...] Read more.
The nucleolus is a dynamic subnuclear structure, which is crucial to the normal operation of the eukaryotic cell. The porcine epidemic diarrhea virus (PEDV), coronavirus nucleocapsid (N) protein, plays important roles in the process of virus replication and cellular infection. Virus infection and transfection showed that N protein was predominately localized in the cytoplasm, but also found in the nucleolus in Vero E6 cells. Furthermore, by utilizing fusion proteins with green fluorescent protein (GFP), deletion mutations or site-directed mutagenesis of PEDV N protein, coupled with live cell imaging and confocal microscopy, it was revealed that, a region spanning amino acids (aa), 71–90 in region 1 of the N protein was sufficient for nucleolar localization and R87 and R89 were critical for its function. We also identified two nuclear export signals (NES, aa221–236, and 325–364), however, only the nuclear export signal (aa325–364) was found to be functional in the context of the full-length N protein. Finally, the activity of this nuclear export signal (NES) was inhibited by the antibiotic Lepomycin B, suggesting that N is exported by a chromosome region maintenance 1-related export pathway. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
Open AccessArticle Molecular Characterization of Major Structural Protein Genes of Avian Coronavirus Infectious Bronchitis Virus Isolates in Southern China
Viruses 2013, 5(12), 3007-3020; doi:10.3390/v5123007
Received: 29 September 2013 / Revised: 9 November 2013 / Accepted: 27 November 2013 / Published: 4 December 2013
Cited by 7 | PDF Full-text (1281 KB) | HTML Full-text | XML Full-text
Abstract
To gain comprehensive genetic information of circulating avian coronavirus infectious bronchitis virus (IBV) isolates in China, analysis of the phylogenetic tree, entropy of the amino acid sequences, and the positive selection as well as computational recombinations of S1, M and N genes of
[...] Read more.
To gain comprehensive genetic information of circulating avian coronavirus infectious bronchitis virus (IBV) isolates in China, analysis of the phylogenetic tree, entropy of the amino acid sequences, and the positive selection as well as computational recombinations of S1, M and N genes of 23 IBV isolates was conducted in the present study. The phylogenetic trees based on the S1, M and N genes exhibited considerably different topology and the CK/CH/LSC/99I-type isolates were the predominant IBVs based on the phylogenetic analysis of S1 gene. Results of entropy of amino acid sequences revealed that the S1 gene had the largest variation; the M gene had less variation than the N gene. Positive selections were detected in not only S1 but also M and N gene proteins. In addition, five S1 gene recombinants between vaccine strain 4/91 and CK/CH/LSC/99I-type field isolate were confirmed. In conclusion, multiple IBV genotypes co-circulated; genetic diversity and positive selections existed in S1, M and N genes; 4/91 vaccine recombinants emerged in China. Our results show that field IBVs in China are continuing to evolve and vaccine strains may have an important role in the appearance of new IBV strains via recombination. In addition, the present study indicates that IBV evolution is driven by both generations of genetic diversity and selection. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
Open AccessArticle Detection and Molecular Diversity of Spike Gene of Porcine Epidemic Diarrhea Virus in China
Viruses 2013, 5(10), 2601-2613; doi:10.3390/v5102601
Received: 16 September 2013 / Revised: 5 October 2013 / Accepted: 15 October 2013 / Published: 22 October 2013
Cited by 20 | PDF Full-text (659 KB) | HTML Full-text | XML Full-text
Abstract
Since late 2010, porcine epidemic diarrhea virus (PEDV) has rapidly disseminated all over the China and caused considerable morbidity and high mortality (up to 100%) in neonatal piglets. 79.66% (141 of 177) pig farms in 29 provinces (excluding Tibet and Hainan, China) and
[...] Read more.
Since late 2010, porcine epidemic diarrhea virus (PEDV) has rapidly disseminated all over the China and caused considerable morbidity and high mortality (up to 100%) in neonatal piglets. 79.66% (141 of 177) pig farms in 29 provinces (excluding Tibet and Hainan, China) and 72.27% (417 of 577) samples were positive for PEDV confirmed by reverse transcription-polymerase chain reaction (RT-PCR). The full-length S genes of representative field strains were sequenced. 33 field strains share 93.5%–99.9% homologies with each other at the nucleotide sequence level and 92.3%–99.8% homologies with each other at the amino acids sequence level. Most field strains have nucleotide deletion and insertion regions, and show lower homologies (93.5%–94.2%) with Chinese classical strain CH/S, however higher homologies (97.1%–99.3%) with recent strain CHGD-1. The phylogenetic analysis showed there are classical strains and variants prevailing in pig herd in China. PEDV has a high detection rate in pig herds in China. Sequence analysis indicated the S genes of recent field strains have heterogeneity and the variants are predominant. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
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 15 | 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
[...] Read more.
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 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
[...] Read more.
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 Altering SARS Coronavirus Frameshift Efficiency Affects Genomic and Subgenomic RNA Production
Viruses 2013, 5(1), 279-294; doi:10.3390/v5010279
Received: 6 December 2012 / Revised: 14 January 2013 / Accepted: 15 January 2013 / Published: 18 January 2013
Cited by 6 | PDF Full-text (833 KB) | HTML Full-text | XML Full-text
Abstract
In previous studies, differences in the amount of genomic and subgenomic RNA produced by coronaviruses with mutations in the programmed ribosomal frameshift signal of ORF1a/b were observed. It was not clear if these differences were due to changes in genomic sequence, the protein
[...] Read more.
In previous studies, differences in the amount of genomic and subgenomic RNA produced by coronaviruses with mutations in the programmed ribosomal frameshift signal of ORF1a/b were observed. It was not clear if these differences were due to changes in genomic sequence, the protein sequence or the frequency of frameshifting. Here, viruses with synonymous codon changes are shown to produce different ratios of genomic and subgenomic RNA. These findings demonstrate that the protein sequence is not the primary cause of altered genomic and subgenomic RNA production. The synonymous codon changes affect both the structure of the frameshift signal and frameshifting efficiency. Small differences in frameshifting efficiency result in dramatic differences in genomic RNA production and TCID50 suggesting that the frameshifting frequency must stay above a certain threshold for optimal virus production. The data suggest that either the RNA sequence or the ratio of viral proteins resulting from different levels of frameshifting affects viral replication. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
Open AccessArticle Protective Role of Toll-like Receptor 3-Induced Type I Interferon in Murine Coronavirus Infection of Macrophages
Viruses 2012, 4(5), 901-923; doi:10.3390/v4050901
Received: 17 April 2012 / Revised: 12 May 2012 / Accepted: 23 May 2012 / Published: 24 May 2012
Cited by 14 | PDF Full-text (2888 KB) | HTML Full-text | XML Full-text
Abstract
Toll-like Receptors (TLRs) sense viral infections and induce production of type I interferons (IFNs), other cytokines, and chemokines. Viral recognition by TLRs and other pattern recognition receptors (PRRs) has been proven to be cell-type specific. Triggering of TLRs with selected ligands can be beneficial
[...] Read more.
Toll-like Receptors (TLRs) sense viral infections and induce production of type I interferons (IFNs), other cytokines, and chemokines. Viral recognition by TLRs and other pattern recognition receptors (PRRs) has been proven to be cell-type specific. Triggering of TLRs with selected ligands can be beneficial against some viral infections. Macrophages are antigen-presenting cells that express TLRs and have a key role in the innate and adaptive immunity against viruses. Coronaviruses (CoVs) are single-stranded, positive-sense RNA viruses that cause acute and chronic infections and can productively infect macrophages. Investigation of the interplay between CoVs and PRRs is in its infancy. We assessed the effect of triggering TLR2, TLR3, TLR4, and TLR7 with selected ligands on the susceptibility of the J774A.1 macrophage cell line to infection with murine coronavirus (mouse hepatitis virus, [MHV]). Stimulation of TLR2, TLR4, or TLR7 did not affect MHV production. In contrast, pre-stimulation of TLR3 with polyinosinic-polycytidylic acid (poly I:C) hindered MHV infection through induction of IFN-β in macrophages. We demonstrate that activation of TLR3 with the synthetic ligand poly I:C mediates antiviral immunity that diminishes (MHV-A59) or suppresses (MHV-JHM, MHV-3) virus production in macrophages. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
Open AccessArticle Evaluation of the Long-Term Effect of Air Filtration on the Occurrence of New PRRSV Infections in Large Breeding Herds in Swine-Dense Regions
Viruses 2012, 4(5), 654-662; doi:10.3390/v4050654
Received: 20 March 2012 / Revised: 21 April 2012 / Accepted: 24 April 2012 / Published: 26 April 2012
Cited by 5 | PDF Full-text (302 KB) | HTML Full-text | XML Full-text
Abstract
Airborne transmission of porcine reproductive and respiratory syndrome virus (PRRSV) is a risk factor for the infection of susceptible populations. Therefore, a long‑term sustainability study of air filtration as a means to reduce this risk was conducted. Participating herds (n = 38) were
[...] Read more.
Airborne transmission of porcine reproductive and respiratory syndrome virus (PRRSV) is a risk factor for the infection of susceptible populations. Therefore, a long‑term sustainability study of air filtration as a means to reduce this risk was conducted. Participating herds (n = 38) were organized into 4 independent cohorts and the effect of air filtration on the occurrence of new PRRSV infections was analyzed at 3 different levels from September 2008 to January 2012 including the likelihood of infection in contemporary filtered and non-filtered herds, the likelihood of infection before and after implementation of filtration and the time to failure in filtered and non-filtered herds. Results indicated that new PRRSV infections in filtered breeding herds were significantly lower than in contemporary non-filtered control herds (P < 0.01), the odds for a new PRRSV infection in breeding herds before filtration was 7.97 times higher than the odds after filtration was initiated (P < 0.01) and the median time to new PRRSV infections in filtered breeding herds of 30 months was significantly longer than the 11 months observed in non-filtered herds (P < 0.01). In conclusion, across all 3 levels of analysis, the long-term effect of air filtration on reducing the occurrence of new PRRSV infections in the study population was demonstrated. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
Figures

Open AccessCommunication Folding and Oligomerization of the gp2b/gp3/gp4 Spike Proteins of Equine Arteritis Virus in Vitro
Viruses 2012, 4(3), 414-423; doi:10.3390/v4030414
Received: 5 January 2012 / Revised: 13 March 2012 / Accepted: 18 March 2012 / Published: 22 March 2012
Cited by 2 | PDF Full-text (1470 KB) | HTML Full-text | XML Full-text
Abstract
Equine arteritis virus (EAV) is a small, positive-stranded RNA virus. The glycoproteins gp2b, gp3 and gp4 form a heterotrimer in the viral envelope, which is required for cell entry of EAV. We describe expression of the ectodomains of the proteins in E. coli
[...] Read more.
Equine arteritis virus (EAV) is a small, positive-stranded RNA virus. The glycoproteins gp2b, gp3 and gp4 form a heterotrimer in the viral envelope, which is required for cell entry of EAV. We describe expression of the ectodomains of the proteins in E. coli and their refolding from inclusion bodies. After extraction of inclusion bodies and dialysis, Gst-, but not His-tagged proteins, refold into a soluble conformation. However, when dialyzed together with Gst-gp3 or with Gst-gp4, His-gp2b and His-gp4 remain soluble and oligomers are obtained by affinity-chromatography. Thus, folding and oligomerization of gp2b, gp3 and gp4 in vitro are interdependent processes. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
Figures

Open AccessArticle The Coronavirus E Protein: Assembly and Beyond
Viruses 2012, 4(3), 363-382; doi:10.3390/v4030363
Received: 24 December 2011 / Revised: 18 February 2012 / Accepted: 27 February 2012 / Published: 8 March 2012
Cited by 16 | PDF Full-text (839 KB) | HTML Full-text | XML Full-text
Abstract
The coronavirus E protein is a small membrane protein that has an important role in the assembly of virions. Recent studies have indicated that the E protein has functions during infection beyond assembly, including in virus egress and in the host stress response.
[...] Read more.
The coronavirus E protein is a small membrane protein that has an important role in the assembly of virions. Recent studies have indicated that the E protein has functions during infection beyond assembly, including in virus egress and in the host stress response. Additionally, the E protein has ion channel activity, interacts with host proteins, and may have multiple membrane topologies. The goal of this review is to highlight the properties and functions of the E protein, and speculate on how they may be related. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
Figures

Open AccessArticle Replication-Competent Recombinant Porcine Reproductive and Respiratory Syndrome (PRRS) Viruses Expressing Indicator Proteins and Antiviral Cytokines
Viruses 2012, 4(1), 102-116; doi:10.3390/v4010102
Received: 23 December 2011 / Revised: 10 January 2012 / Accepted: 14 January 2012 / Published: 18 January 2012
Cited by 7 | PDF Full-text (1556 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) can subvert early innate immunity, which leads to ineffective antimicrobial responses. Overcoming immune subversion is critical for developing vaccines and other measures to control this devastating swine virus. The overall goal of this work was to
[...] Read more.
Porcine reproductive and respiratory syndrome virus (PRRSV) can subvert early innate immunity, which leads to ineffective antimicrobial responses. Overcoming immune subversion is critical for developing vaccines and other measures to control this devastating swine virus. The overall goal of this work was to enhance innate and adaptive immunity following vaccination through the expression of interferon (IFN) genes by the PRRSV genome. We have constructed a series of recombinant PRRS viruses using an infectious PRRSV cDNA clone (pCMV-P129). Coding regions of exogenous genes, which included Renilla luciferase (Rluc), green and red fluorescent proteins (GFP and DsRed, respectively) and several interferons (IFNs), were constructed and expressed through a unique subgenomic mRNA placed between ORF1b and ORF2 of the PRRSV infectious clone. The constructs, which expressed Rluc, GFP, DsRed, efficiently produced progeny viruses and mimicked the parental virus in both MARC-145 cells and porcine macrophages. In contrast, replication of IFN-expressing viruses was attenuated, similar to the level of replication observed after the addition of exogenous IFN. Furthermore, the IFN expressing viruses inhibited the replication of a second PRRS virus co-transfected or co-infected. Inhibition by the different IFN subtypes corresponded to their anti-PRRSV activity, i.e., IFNω5 » IFNα1 > IFN-β > IFNδ3. In summary, the indicator-expressing viruses provided an efficient means for real-time monitoring of viral replication thus allowing high‑throughput elucidation of the role of host factors in PRRSV infection. This was shown when they were used to clearly demonstrate the involvement of tumor susceptibility gene 101 (TSG101) in the early stage of PRRSV infection. In addition, replication‑competent IFN-expressing viruses may be good candidates for development of modified live virus (MLV) vaccines, which are capable of reversing subverted innate immune responses and may induce more effective adaptive immunity against PRRSV infection. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)

Review

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Open AccessReview Mechanisms of Coronavirus Cell Entry Mediated by the Viral Spike Protein
Viruses 2012, 4(6), 1011-1033; doi:10.3390/v4061011
Received: 8 May 2012 / Revised: 13 June 2012 / Accepted: 14 June 2012 / Published: 20 June 2012
Cited by 57 | PDF Full-text (978 KB) | HTML Full-text | XML Full-text
Abstract
Coronaviruses are enveloped positive-stranded RNA viruses that replicate in the cytoplasm. To deliver their nucleocapsid into the host cell, they rely on the fusion of their envelope with the host cell membrane. The spike glycoprotein (S) mediates virus entry and is a primary
[...] Read more.
Coronaviruses are enveloped positive-stranded RNA viruses that replicate in the cytoplasm. To deliver their nucleocapsid into the host cell, they rely on the fusion of their envelope with the host cell membrane. The spike glycoprotein (S) mediates virus entry and is a primary determinant of cell tropism and pathogenesis. It is classified as a class I fusion protein, and is responsible for binding to the receptor on the host cell as well as mediating the fusion of host and viral membranes—A process driven by major conformational changes of the S protein. This review discusses coronavirus entry mechanisms focusing on the different triggers used by coronaviruses to initiate the conformational change of the S protein: receptor binding, low pH exposure and proteolytic activation. We also highlight commonalities between coronavirus S proteins and other class I viral fusion proteins, as well as distinctive features that confer distinct tropism, pathogenicity and host interspecies transmission characteristics to coronaviruses. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
Open AccessReview Recent Progress in Studies of Arterivirus- and Coronavirus-Host Interactions
Viruses 2012, 4(6), 980-1010; doi:10.3390/v4060980
Received: 7 May 2012 / Revised: 30 May 2012 / Accepted: 14 June 2012 / Published: 19 June 2012
Cited by 19 | PDF Full-text (890 KB) | HTML Full-text | XML Full-text
Abstract
Animal coronaviruses, such as infectious bronchitis virus (IBV), and arteriviruses, such as porcine reproductive and respiratory syndrome virus (PRRSV), are able to manifest highly contagious infections in their specific native hosts, thereby arising in critical economic damage to animal industries. This review discusses
[...] Read more.
Animal coronaviruses, such as infectious bronchitis virus (IBV), and arteriviruses, such as porcine reproductive and respiratory syndrome virus (PRRSV), are able to manifest highly contagious infections in their specific native hosts, thereby arising in critical economic damage to animal industries. This review discusses recent progress in studies of virus-host interactions during animal and human coronavirus and arterivirus infections, with emphasis on IBV-host cell interactions. These interactions may be directly involved in viral replication or lead to the alteration of certain signaling pathways, such as cell stress response and innate immunity, to facilitate viral replication and pathogenesis. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
Open AccessReview Regulatory T Cells in Arterivirus and Coronavirus Infections: Do They Protect Against Disease or Enhance it?
Viruses 2012, 4(5), 833-846; doi:10.3390/v4050833
Received: 2 April 2012 / Revised: 3 May 2012 / Accepted: 7 May 2012 / Published: 15 May 2012
Cited by 16 | PDF Full-text (232 KB) | HTML Full-text | XML Full-text
Abstract
Regulatory T cells (Tregs) are a subset of T cells that are responsible for maintaining peripheral immune tolerance and homeostasis. The hallmark of Tregs is the expression of the forkhead box P3 (FoxP3) transcription factor. Natural regulatory T cells (nT
[...] Read more.
Regulatory T cells (Tregs) are a subset of T cells that are responsible for maintaining peripheral immune tolerance and homeostasis. The hallmark of Tregs is the expression of the forkhead box P3 (FoxP3) transcription factor. Natural regulatory T cells (nTregs) are a distinct population of T cells that express CD4 and FoxP3. nTregs develop in the thymus and function in maintaining peripheral immune tolerance. Other CD4+, CD4-CD8-, and CD8+CD28- T cells can be induced to acquire regulatory function by antigenic stimulation, depending on the cytokine milieu. Inducible (or adaptive) Tregs frequently express high levels of the interleukin 2 receptor (CD25). Atypical Tregs express FoxP3 and CD4 but have no surface expression of CD25. Type 1 regulatory T cells (Tr1 cells) produce IL-10, while T helper 3 cells (Th3) produce TGF-β. The function of inducible Tregs is presumably to maintain immune homeostasis, especially in the context of chronic inflammation or infection. Induction of Tregs in coronaviral infections protects against the more severe forms of the disease attributable to the host response. However, arteriviruses have exploited these T cell subsets as a means to dampen the immune response allowing for viral persistence. Treg induction or activation in the pathogenesis of disease has been described in both porcine reproductive and respiratory syndrome virus, lactate dehydrogenase elevating virus, and mouse hepatitis virus. This review discusses the development and biology of regulatory T cells in the context of arteriviral and coronaviral infection. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
Open AccessReview Post-Transcriptional Control of Type I Interferon Induction by Porcine Reproductive and Respiratory Syndrome Virus in Its Natural Host Cells
Viruses 2012, 4(5), 725-733; doi:10.3390/v4050725
Received: 29 March 2012 / Revised: 18 April 2012 / Accepted: 24 April 2012 / Published: 2 May 2012
Cited by 4 | PDF Full-text (185 KB) | HTML Full-text | XML Full-text
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is not only a poor inducer of type I interferon but also inhibits the efficient induction of type I interferon by porcine transmissible gastroenteritis virus (TGEV) and synthetic dsRNA molecules, Poly I:C. However, the mechanistic basis
[...] Read more.
Porcine reproductive and respiratory syndrome virus (PRRSV) is not only a poor inducer of type I interferon but also inhibits the efficient induction of type I interferon by porcine transmissible gastroenteritis virus (TGEV) and synthetic dsRNA molecules, Poly I:C. However, the mechanistic basis by which PRRSV interferes with the induction of type I interferon in its natural host cells remains less well defined. The purposes of this review are to summarize the key findings in supporting the post-transcriptional control of type I interferon in its natural host cells and to propose the possible role of translational control in the regulation of type I interferon induction by PRRSV. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
Open AccessReview Interplay between Interferon-Mediated Innate Immunity and Porcine Reproductive and Respiratory Syndrome Virus
Viruses 2012, 4(4), 424-446; doi:10.3390/v4040424
Received: 30 January 2012 / Revised: 15 March 2012 / Accepted: 18 March 2012 / Published: 2 April 2012
Cited by 51 | PDF Full-text (2045 KB) | HTML Full-text | XML Full-text
Abstract
Innate immunity is the first line of defense against viral infection, and in turn, viruses have evolved to evade host immune surveillance. As a result, viruses may persist in host and develop chronic infections. Type I interferons (IFN-α/β) are among the most potent
[...] Read more.
Innate immunity is the first line of defense against viral infection, and in turn, viruses have evolved to evade host immune surveillance. As a result, viruses may persist in host and develop chronic infections. Type I interferons (IFN-α/β) are among the most potent antiviral cytokines triggered by viral infections. Porcine reproductive and respiratory syndrome (PRRS) is a disease of pigs that is characterized by negligible induction of type I IFNs and viral persistence for an extended period. For IFN production, RIG-I/MDA5 and JAK-STAT pathways are two major signaling pathways, and recent studies indicate that PRRS virus is armed to modulate type I IFN responses during infection. This review describes the viral strategies for modulation of type I IFN responses. At least three non‑structural proteins (Nsp1, Nsp2, and Nsp11) and a structural protein (N nucleocapsid protein) have been identified and characterized to play roles in the IFN suppression and NF-κB pathways. Nsp’s are early proteins while N is a late protein, suggesting that additional signaling pathways may be involved in addition to the IFN pathway. The understanding of molecular bases for virus-mediated modulation of host innate immune signaling will help us design new generation vaccines and control PRRS. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)
Figures

Other

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Open AccessBrief Report Sequence Heterogeneity of the ORF3 Gene of Porcine Epidemic Diarrhea Viruses Field Samples in Fujian, China, 2010–2012
Viruses 2013, 5(10), 2375-2383; doi:10.3390/v5102375
Received: 7 August 2013 / Revised: 13 September 2013 / Accepted: 19 September 2013 / Published: 30 September 2013
Cited by 6 | PDF Full-text (779 KB) | HTML Full-text | XML Full-text
Abstract
Twenty-seven field samples that showed positive in PEDV detection were collected from different farms of Fujian province from 2010 to 2012. Their heterogeneity was investigated by analysis of the ORF3 gene because of its potential function as a representation of virulence. According to
[...] Read more.
Twenty-seven field samples that showed positive in PEDV detection were collected from different farms of Fujian province from 2010 to 2012. Their heterogeneity was investigated by analysis of the ORF3 gene because of its potential function as a representation of virulence. According to the results, six Fujian strains in Group 1 showed a different genotype with unique point mutations, which might be used in differentiation between PEDV groups and brought potential antigenic variation. P55 and five reference strains in Group 2 had a long length deletion, showing another genotype and might be involved in the variation of virulence. Phylogenetic analysis revealed that the collected Fujian strains were very distant from the vaccine development strain CV777, which might be the reason why the vaccine was inefficient to control the disease. The results can help to reconsider the strategy of PEDV vaccine management and prevent outbreaks of PEDV-induced diarrhea more efficiently. Full article
(This article belongs to the Special Issue Animal Arteriviruses and Coronaviruses)

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