The Function of the PRRSV–Host Interactions and Their Effects on Viral Replication and Propagation in Antiviral Strategies

Porcine reproductive and respiratory syndrome virus (PRRSV) affects the global swine industry and causes disastrous economic losses each year. The genome of PRRSV is an enveloped single-stranded positive-sense RNA of approximately 15 kb. The PRRSV replicates primarily in alveolar macrophages of pig lungs and lymphatic organs and causes reproductive problems in sows and respiratory symptoms in piglets. To date, studies on how PRRSV survives in the host, the host immune response against viral infections, and pathogenesis, have been reported. PRRSV vaccines have been developed, including inactive virus, modified live virus, attenuated live vaccine, DNA vaccine, and immune adjuvant vaccines. However, there are certain problems with the durability and effectiveness of the licensed vaccines. Moreover, the high variability and fast-evolving populations of this RNA virus challenge the design of PRRSV vaccines, and thus effective vaccines against PRRSV have not been developed successfully. As is well known, viruses interact with the host to escape the host’s immune response and then replicate and propagate in the host, which is the key to virus survival. Here, we review the complex network and the mechanism of PRRSV–host interactions in the processes of virus infection. It is critical to develop novel antiviral strategies against PRRSV by studying these host–virus interactions and structures to better understand the molecular mechanisms of PRRSV immune escape.

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Porcine Reproductive and Respiratory Syndrome Virus: Immune Escape and Application of Reverse Genetics in Attenuated Live Vaccine Development

Vaccines ◽

10.3390/vaccines9050480 ◽

2021 ◽

Vol 9 (5) ◽

pp. 480

Author(s):

Honglei Wang ◽

Yangyang Xu ◽

Wenhai Feng

Keyword(s):

Immune Responses ◽

Reverse Genetics ◽

Vaccine Development ◽

Immune Escape ◽

Rna Virus ◽

Economic Losses ◽

Respiratory Syndrome Virus ◽

Live Vaccines ◽

Host Immune Responses ◽

Inactivated Vaccines

Porcine reproductive and respiratory syndrome virus (PRRSV), an RNA virus widely prevalent in pigs, results in significant economic losses worldwide. PRRSV can escape from the host immune response in several processes. Vaccines, including modified live vaccines and inactivated vaccines, are the best available countermeasures against PRRSV infection. However, challenges still exist as the vaccines are not able to induce broad protection. The reason lies in several facts, mainly the variability of PRRSV and the complexity of the interaction between PRRSV and host immune responses, and overcoming these obstacles will require more exploration. Many novel strategies have been proposed to construct more effective vaccines against this evolving and smart virus. In this review, we will describe the mechanisms of how PRRSV induces weak and delayed immune responses, the current vaccines of PRRSV, and the strategies to develop modified live vaccines using reverse genetics systems.

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Porcine Reproductive and Respiratory Syndrome Virus Activates Lipophagy To Facilitate Viral Replication through Downregulation of NDRG1 Expression

Journal of Virology ◽

10.1128/jvi.00526-19 ◽

2019 ◽

Vol 93 (17) ◽

Cited By ~ 4

Author(s):

Jiang Wang ◽

Jiao-Yang Liu ◽

Ke-Yu Shao ◽

Ying-Qian Han ◽

Guo-Li Li ◽

...

Keyword(s):

Lipid Metabolism ◽

Virus Assembly ◽

Rna Virus ◽

Progeny Virus ◽

Economic Losses ◽

Respiratory Syndrome Virus ◽

Swine Industry ◽

Effective Strategies ◽

Single Positive ◽

Negative Role

ABSTRACTAutophagy maintains cellular homeostasis by degrading organelles, proteins, and lipids in lysosomes. Autophagy is involved in the innate and adaptive immune responses to a variety of pathogens. Some viruses can hijack host autophagy to enhance their replication. However, the role of autophagy in porcine reproductive and respiratory syndrome virus (PRRSV) infection is unclear. Here, we show that N-Myc downstream-regulated gene 1 (NDRG1) deficiency induced autophagy, which facilitated PRRSV replication by regulating lipid metabolism. NDRG1 mRNA is expressed ubiquitously in most porcine tissues and most strongly in white adipose tissue. PRRSV infection downregulated the expression of NDRG1 mRNA and protein, while NDRG1 deficiency contributed to PRRSV RNA replication and progeny virus assembly. NDRG1 deficiency reduced the number of intracellular lipid droplets (LDs), but the expression levels of key genes in lipogenesis and lipolysis were not altered. Our results also show that NDRG1 deficiency promoted autophagy and increased the subsequent yields of hydrolyzed free fatty acids (FFAs). The reduced LD numbers, increased FFA levels, and enhanced PRRSV replication were abrogated in the presence of an autophagy inhibitor. Overall, our findings suggest that NDRG1 plays a negative role in PRRSV replication by suppressing autophagy and LD degradation.IMPORTANCEPorcine reproductive and respiratory syndrome virus (PRRSV), an enveloped single-positive-stranded RNA virus, causes acute respiratory distress in piglets and reproductive failure in sows. It has led to tremendous economic losses in the swine industry worldwide since it was first documented in the late 1980s. Vaccination is currently the major strategy used to control the disease. However, conventional vaccines and other strategies do not provide satisfactory or sustainable prevention. Therefore, safe and effective strategies to control PRRSV are urgently required. The significance of our research is that we demonstrate a previously unreported relationship between PRRSV, NDRG1, and lipophagy in the context of viral infection. Furthermore, our data point to a new role for NDRG1 in autophagy and lipid metabolism. Thus, NDRG1 and lipophagy will have significant implications for understanding PRRSV pathogenesis for developing new therapeutics.

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Challenges for Porcine Reproductive and Respiratory Syndrome (PRRS) Vaccine Design: Reviewing Virus Glycoprotein Interactions with CD163 and Targets of Virus Neutralization

Veterinary Sciences ◽

10.3390/vetsci6010009 ◽

2019 ◽

Vol 6 (1) ◽

pp. 9 ◽

Cited By ~ 6

Author(s):

Ana Stoian ◽

Raymond Rowland

Keyword(s):

Vaccine Development ◽

Noncovalent Interactions ◽

Rna Virus ◽

Neutralizing Antibody ◽

Complex Surface ◽

Surface Proteins ◽

Respiratory Syndrome Virus ◽

Swine Industry ◽

Live Virus ◽

Potential Vaccine

One of the main participants associated with the onset and maintenance of the porcine respiratory disease complex (PRDC) syndrome is porcine reproductive and respiratory syndrome virus (PRRSV), an RNA virus that has plagued the swine industry for 30 years. The development of effective PRRS vaccines, which deviate from live virus designs, would be an important step towards the control of PRRS. Potential vaccine antigens are found in the five surface proteins of the virus, which form covalent and multiple noncovalent interactions and possess hypervariable epitopes. Consequences of this complex surface structure include antigenic variability and escape from immunity, thus presenting challenges in the development of new vaccines capable of generating broadly sterilizing immunity. One potential vaccine target is the induction of antibody that disrupts the interaction between the macrophage CD163 receptor and the GP2, GP3, and GP4 heterotrimer that protrudes from the surface of the virion. Studies to understand this interaction by mapping mutations that appear following the escape of virus from neutralizing antibody identify the ectodomain regions of GP5 and M as important immune sites. As a target for antibody, GP5 possesses a conserved epitope flanked by N-glycosylation sites and hypervariable regions, a pattern of conserved epitopes shared by other viruses. Resolving this apparent conundrum is needed to advance PRRS vaccine development.

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Porcine Reproductive and Respiratory Syndrome Virus Reverse Genetics and the Major Applications

Viruses ◽

10.3390/v12111245 ◽

2020 ◽

Vol 12 (11) ◽

pp. 1245

Author(s):

Jayeshbhai Chaudhari ◽

Hiep L. X. Vu

Keyword(s):

Viral Genome ◽

Reverse Genetics ◽

Rna Virus ◽

Site Directed Mutagenesis ◽

Economic Losses ◽

Respiratory Syndrome Virus ◽

Cdna Clones ◽

Swine Industry ◽

Host Interaction ◽

Foreign Genes

Porcine reproductive and respiratory syndrome virus (PRRSV) is a positive sense, single-stranded RNA virus that is known to infect only pigs. The virus emerged in the late 1980s and became endemic in most swine producing countries, causing substantial economic losses to the swine industry. The first reverse genetics system for PRRSV was reported in 1998. Since then, several infectious cDNA clones for PRRSV have been constructed. The availability of these infectious cDNA clones has facilitated the genetic modifications of the viral genome at precise locations. Common approaches to manipulate the viral genome include site-directed mutagenesis, deletion of viral genes or gene fragments, insertion of foreign genes, and swapping genes between PRRSV strains or between PRRSV and other members of the Arteriviridae family. In this review, we describe the approaches to construct an infectious cDNA for PRRSV and the ten major applications of these infectious clones to study virus biology and virus–host interaction, and to design a new generation of vaccines with improved levels of safety and efficacy.

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Antagonizing Interferon-Mediated Immune Response by Porcine Reproductive and Respiratory Syndrome Virus

BioMed Research International ◽

10.1155/2014/315470 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 22

Author(s):

Rong Wang ◽

Yan-Jin Zhang

Keyword(s):

Immune Response ◽

Neutralizing Antibodies ◽

Innate Immune ◽

Economic Losses ◽

Respiratory Syndrome Virus ◽

First Line ◽

Swine Industry ◽

Antiviral Signaling ◽

Cell Mediated Immune Response ◽

Host Innate Immune Response

Interferons (IFNs) are important components in innate immunity involved in the first line of defense to protect host against viral infection. Porcine reproductive and respiratory syndrome virus (PRRSV) leads to severe economic losses for swine industry since being first identified in early 1990s. PRRSV interplays with host IFN production and IFN-activated signaling, which may contribute to the delayed onset and low level of neutralizing antibodies, as well as weak cell-mediated immune response in infected pigs. PRRSV encodes several proteins that act as antagonists for the IFN signaling. In this review, we summarized the various strategies used by PRRSV to antagonize IFN production and thwart IFN-activated antiviral signaling, as well as the variable interference with IFN-mediated immune response by different PRRSV strains. Thorough understanding of the interaction between PRRSV and host innate immune response will facilitate elucidation of PRRSV pathogenesis and development of a better strategy to control PRRS.

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MicroRNA miR-24-3p Promotes Porcine Reproductive and Respiratory Syndrome Virus Replication through Suppression of Heme Oxygenase-1 Expression

Journal of Virology ◽

10.1128/jvi.02810-14 ◽

2015 ◽

Vol 89 (8) ◽

pp. 4494-4503 ◽

Cited By ~ 44

Author(s):

Shuqi Xiao ◽

Xue Wang ◽

Huaibao Ni ◽

Na Li ◽

Angke Zhang ◽

...

Keyword(s):

Virus Replication ◽

Heme Oxygenase ◽

Direct Interaction ◽

Economic Losses ◽

Respiratory Syndrome Virus ◽

Heme Oxygenase 1 ◽

Swine Industry ◽

Cellular Mirnas ◽

Host Interactions ◽

Posttranscriptional Level

ABSTRACTPorcine reproductive and respiratory syndrome virus (PRRSV) is one of the most economically important viruses affecting the swine industry worldwide. Our previous research showed that PRRSV downregulates the expression of heme oxygenase-1 (HO-1), a pivotal cytoprotective enzyme, postinfection and that overexpression of HO-1 inhibits PRRSV replication. MicroRNAs regulate gene expression at the posttranscriptional level and have recently been demonstrated to play vital roles in pathogen-host interactions. The present study sought to determine whether microRNAs modulate HO-1 expression and, by doing so, regulate PRRSV replication. Using bioinformatic prediction and experimental verification, we demonstrate that HO-1 expression is regulated by miR-24-3p. A direct interaction between miR-24-3p and HO-1 mRNA was confirmed using a number of approaches. Overexpression of miR-24-3p significantly decreased HO-1 mRNA and protein levels. PRRSV infection induced miR-24-3p expression to facilitate viral replication. The suppressive effect of HO-1 induction by protoporphyrin IX cobalt chloride (CoPP; a classical inducer of HO-1 expression) on PRRSV replication in MARC-145 cells and primary porcine alveolar macrophages could also be reversed by overexpression of miR-24-3p. Collectively, these results suggested that miR-24-3p promotes PRRSV replication through suppression of HO-1 expression, which not only provides new insights into virus-host interactions during PRRSV infection but also suggests potential new antiviral strategies against PRRSV infection.IMPORTANCEMicroRNAs (miRNAs) play vital roles in viral infections by regulating the expression of viral or host genes at the posttranscriptional level. Heme oxygenase-1 (HO-1), a pivotal cytoprotective enzyme, has antiviral activity for a number of viruses, such as Ebola virus, hepatitis C virus, human immunodeficiency virus, and our focus, PRRSV, which causes great economic losses each year in the swine industry worldwide. Here, we show that PRRSV infection induces host miRNA miR-24-3p expression and that miR-24-3p regulates HO-1 expression through both mRNA degradation and translation repression. Suppression of HO-1 expression by miR-24-3p facilitates PRRSV replication. This work lends credibility to the hypothesis that an arterivirus can manipulate cellular miRNAs to enhance virus replication by regulating antiviral responses following viral infection. Therefore, our findings provide new insights into the pathogenesis of PRRSV.

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Identification of E2 with improved secretion and immunogenicity against CSFV in piglets

10.21203/rs.2.18234/v2 ◽

2020 ◽

Author(s):

Huiling Xu ◽

Yanli Wang ◽

Guangwei Han ◽

Weihuan Fang ◽

fang he

Keyword(s):

Single Dose ◽

Signal Peptide ◽

Classical Swine Fever Virus ◽

Subunit Vaccine ◽

Classical Swine Fever ◽

Cost Effective ◽

Fever Virus ◽

Economic Losses ◽

Swine Industry ◽

Virus Challenge

Abstract Background: Outbreaks of Classical swine fever virus (CSFV) cause significant economic losses in the swine industry. Vaccination is the major method to prevent and control the disease. As live attenuated vaccines fail to elicit differentiable immunity between infected and vaccinated animals, subunit vaccine was considered as an alternative candidate to prevent and eradicate CSFV. Subunit vaccines present advantages in DIVA immunogenicity and safety. The technology was limited due to the low yield and the high cost with multiple and large doses. The native E2 signal peptide has not been well defined before. Here, the aim of this study is to develop a cost-effective and efficacious E2 vaccine candidate against CSFV with signal peptide and E2 sequence selection. Results: A novel CSFV E2 sequence (E2ZJ) was identified from an epidemic strain of Zhejiang for outstanding secretion in baculovirus and enhanced immunogenicity. E2 secretion induced with the selected signal peptide, SPZJ (SP23), increase at least 50% as compared to any other signal peptides tested. Besides, unique antigenic features were identified in E2ZJ. E2ZJ elicited CSFV antibodies at the earlier stage than other E2 types tested in mice. Moreover, higher level of neutralization antibodies against both genotypes 1 and 2 CSFV with E2ZJ was detected than other E2s with the same dosage. Further, in piglets, E2ZJ successfully elicited neutralizing immunity. A single dose of 5 μg of E2ZJ was sufficient to induce protective antibodies against CSFV in piglets and provided 100% protection against lethal virus challenge. Conclusions: Our studies provide evidence that E2ZJ guided by a novel E2 signal peptide (SPZJ) was efficiently secreted and presented significantly improved immunogenicity than conventional E2 vaccines. Moreover, a single dose of 5 μg E2ZJ is efficacious against CSFV in piglets. Keywords: Classical swine fever virus; novel signal peptide; SPZJ-E2ZJ; subunit vaccine; protective immunity

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MicroRNA-376b-3p Promotes Porcine Reproductive and Respiratory Syndrome Virus Replication by Targeting Viral Restriction Factor TRIM22

Journal of Virology ◽

10.1128/jvi.01597-21 ◽

2021 ◽

Author(s):

Jing Chen ◽

Shijie Zhao ◽

Zhiying Cui ◽

Wen Li ◽

Pengli Xu ◽

...

Keyword(s):

Viral Infections ◽

Antiviral Effect ◽

Economic Losses ◽

Respiratory Syndrome Virus ◽

Restriction Factor ◽

Transcriptional Level ◽

Swine Industry ◽

Human Virus ◽

N Protein ◽

Novel Strategy

Porcine reproductive and respiratory syndrome virus is a major economically significant pathogen and has evolved several strategies to evade host's antiviral response and provide favorable conditions for survival. In the present study, we demonstrated that a host microRNA, miR-376b-3p, was upregulated by PRRSV infection through the viral components, nsp4 and nsp11, and miR-376b-3p can directly target tripartite motif-containing 22 (TRIM22) to impair its anti-PRRSV activity, thus facilitating the replication of PRRSV. Meanwhile, we found that TRIM22 induced degradation of the nucleocapsid protein (N) of PRRSV by interacting with N protein to inhibit PRRSV replication, and further study indicated that TRIM22 could enhance the activation of lysosomal pathway by interacting with LC3 to induce lysosomal degradation of N protein. In conclusion, PRRSV increased miR-376b-3p expression and hijacked the host miR-376b-3p to promote PRRSV replication by impairing the antiviral effect of TRIM22. Therefore, our finding outlines a novel strategy of immune evasion exerted by PRRSV, which is helpful for better understanding the pathogenesis of PRRSV. IMPORTANCE Porcine reproductive and respiratory syndrome virus (PRRSV) causes enormous economic losses each year in the swine industry worldwide. MicroRNAs (miRNAs) play important roles during viral infections via modulating the expression of viral or host genes at post-transcriptional level. TRIM22 has recently been identified as a key restriction factor that inhibited the replication of a number of human virus such as HIV, ECMV, HCV, HBV, IAV, and RSV. Here we showed that host miR-376b-3p could be up-regulated by PRRSV and functioned to impair the anti-PRRSV role of TRIM22 to facilitate PRRSV replication. Meanwhile, we found that TRIM22 inhibited the replication of PRRSV by interacting with viral N protein and accelerating its degradation through the lysosomal pathway. Collectively, the paper described a novel mechanism that PRRSV exploited the host miR-376b-3p to evade antiviral responses and provided a new insight into the study of virus-host interactions.

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Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus Induces Interleukin-17 Production via Activation of the IRAK1-PI3K-p38MAPK-C/EBPβ/CREB Pathways

Journal of Virology ◽

10.1128/jvi.01100-19 ◽

2019 ◽

Vol 93 (21) ◽

Cited By ~ 2

Author(s):

Honglei Wang ◽

Li Du ◽

Fang Liu ◽

Zeyu Wei ◽

Li Gao ◽

...

Keyword(s):

Lung Inflammation ◽

Molecular Mechanisms ◽

Nonstructural Protein ◽

Severe Pneumonia ◽

Pi3k Inhibitor ◽

Economic Losses ◽

Respiratory Syndrome Virus ◽

Binding Motif ◽

Interleukin 17 ◽

Highly Pathogenic

ABSTRACT Porcine reproductive and respiratory syndrome virus (PRRSV) is widely prevalent in pigs, resulting in significant economic losses worldwide. A compelling impact of PRRSV infection is severe pneumonia. In the present study, we found that interleukin-17 (IL-17) was upregulated by PRRSV infection. Subsequently, we demonstrated that PI3K and p38MAPK signaling pathways were essential for PRRSV-induced IL-17 production as addition of phosphatidylinositol 3-kinase (PI3K) and p38MAPK inhibitors dramatically reduced IL-17 production. Furthermore, we show here that deleting the C/EBPβ and CREB binding motif in porcine IL-17 promoter abrogated its activation and that knockdown of C/EBPβ and CREB remarkably impaired PRRSV-induced IL-17 production, suggesting that IL-17 expression was dependent on C/EBPβ and CREB. More specifically, we demonstrate that PRRSV nonstructural protein 11 (nsp11) induced IL-17 production, which was also dependent on PI3K-p38MAPK-C/EBPβ/CREB pathways. We then show that Ser74 and Phe76 amino acids were essential for nsp11 to induce IL-17 production and viral rescue. In addition, IRAK1 was required for nsp11 to activate PI3K and enhance IL-17 expression by interacting with each other. Importantly, we demonstrate that PI3K inhibitor significantly suppressed IL-17 production and lung inflammation caused by HP-PRRSV in vivo, implicating that higher IL-17 level induced by HP-PRRSV might be associated with severe lung inflammation. These findings provide new insights onto the molecular mechanisms of the PRRSV-induced IL-17 production and help us further understand the pathogenesis of PRRSV infection. IMPORTANCE Highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) associated with severe pneumonia has been one of the most important viral pathogens in pigs. IL-17 is a proinflammatory cytokine that might be associated with the strong inflammation caused by PRRSV. Therefore, we sought to determine whether PRRSV infection affects IL-17 expression, and if so, determine this might partially explain the underlying mechanisms for the strong inflammation in HP-PRRSV-infected pigs, especially in lungs. Here, we show that PRRSV significantly induced IL-17 expression, and we subsequently dissected the molecular mechanisms about how PRRSV regulated IL-17 production. Furthermore, we show that Ser74 and Phe76 in nsp11 were indispensable for IL-17 production and viral replication. Importantly, we demonstrated that PI3K inhibitor impaired IL-17 production and alleviated lung inflammation caused by HP-PRRSV infection. Our findings will help us for a better understanding of PRRSV pathogenesis.

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PRRSV Vaccine Strain-Induced Secretion of Extracellular ISG15 Stimulates Porcine Alveolar Macrophage Antiviral Response against PRRSV

Viruses ◽

10.3390/v12091009 ◽

2020 ◽

Vol 12 (9) ◽

pp. 1009

Author(s):

Hongbin Liu ◽

Bingjun Shi ◽

Zhigang Zhang ◽

Bao Zhao ◽

Guangming Zhao ◽

...

Keyword(s):

Monoclonal Antibody ◽

Vaccine Strain ◽

Sandwich Elisa ◽

Respiratory Syndrome Virus ◽

Enzyme Linked Immunosorbent Assay ◽

Porcine Alveolar Macrophage ◽

Type I ◽

Swine Industry ◽

Host Interactions ◽

Isg15 Expression

Porcine reproductive and respiratory syndrome virus (PRRSV) has disrupted the global swine industry since the 1980s. PRRSV-host interactions are largely still unknown but may involve host ISG15 protein. In this study, we developed a monoclonal antibody (Mab-3D5E6) specific for swine ISG15 (sISG15) by immunizing mice with recombinant sISG15. A sandwich enzyme-linked immunosorbent assay (ELISA) incorporating this sISG15-specific Mab was developed to detect sISG15 and provided a lower limit of sISG15 detection of 200 pg/mL. ELISA results demonstrated that infection of porcine alveolar macrophages (PAMs) with low-virulence or attenuated PRRSV vaccine strains induced intracellular ISG15 expression that was independent of type I IFN production, while PAMs infection with a PRRSV vaccine strain promoted extracellular ISG15 secretion from infected PAMs. Conversely, the addition of recombinant sISG15 to PAMs mimicked natural extracellular ISG15 effects whereby sISG15 functioned as a cytokine by activating PAMs. Once activated, PAMs could inhibit PRRSV replication and resist infection with PRRSV vaccine strain TJM. In summary, a sandwich ELISA incorporating homemade anti-ISG15 Mab detected ISG15 secretion induced by PAMs infection with a PRRSV vaccine strain. Recombinant ISG15 added to cells exhibited cytokine-like activity that stimulated PAMs to assume an anti-viral state that enabled them to inhibit PRRSV replication and resist viral infection.

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