Adverse Effects of Inactivated Foot-and-Mouth Disease Vaccine—Possible Causes Analysis and Countermeasures

Foot-and-mouth disease (FMD) is an infectious and sometimes fatal viral disease that affects cloven-hoofed animals, and Chinese government adopts compulsory immunization measures for FMD. The adverse effects of FMD vaccine to pigs, cattle and goats have been reported increasingly frequent during the spring and autumn seasons when large numbers of farm livestock are vaccinated. The financial losses caused by vaccine adverse effects have been a serious concern for both farmers and primary prevention personnel. There are various causative factors reported to involve into adverse effect of FMD vaccine, including the inappropriate vaccine production, transportation and storage, livestock poor tolerance, and unqualified vaccinating manipulations. Symptomatic treatment and early drug prevention have a certain effect on the adverse effects. To analyze causes and propose countermeasures, in the current study possible reasons during the production and processing procedures of inactivated FMD vaccine were reviewed and corresponding countermeasures were recommended. The review may provide references for better use of vaccine to prevent FMD.

Porcine epidemic diarrhea virus nsp14 inhibits NF-κB pathway activation by targeting the IKK complex and p65

Coronaviruses(CoVs)are a group of related enveloped RNA viruses that have severe consequences in a wide variety of animals by causing respiratory,enteric or systemic diseases.Porcine epidemic diarrhea virus(PEDV)is an economically important CoV distributed worldwide that causes diarrhea in pigs.nsp14 is a nonstructural protein of PEDV that is involved in regulation of innate immunity and viral replication.However,the function and mechanism by which nsp14 modulates and manipulates host immune responses remain largely unknown.Here,we report that PEDV nsp14 is an NF-κB pathway antagonist.Overexpression PEDV nsp14 protein remarkably decreases SeV-,poly(I:C)-and TNF-α-induced NF-κB activation.Meanwhile,expression of proinflammatory cytokines is suppressed by nspl4.nsp14 inhibits the phosphorylation of IKKs by interacting with IKKs and p65.Furthermore,nsp14 suppresses TNF-α-induced phosphorylation and nuclear import of p65.Overexpression nsp14 considerably increases PEDV replication.These results suggest a novel mechanism employed by PEDV to suppress the host antiviral response,providing insights that can guide the development of antivirals against CoVs.

Genomic similarity and antibody-dependent enhancement of immune serum potentially affect the protective efficacy of commercial MLV vaccines against NADC30-like PRRSV

Porcine reproductive and respiratory syndrome(PRRS)is one of the most significant diseases affecting the pig industry worldwide.The PRRSV mutation rate is the highest among the RNA viruses.To date,NADC30-like PRRSV and highly pathogenic PRRSV(HP-PRRSV)are the dominant epidemic strains in China;however,commercial vaccines do not always provide sufficient cross-protection,and the reasons for insufficient protection are unclear.This study isolated a wild-type NADC30-like PRRSV,SX-YL1806,from Shaanxi Province.Vaccination challenge experiments in piglets showed that commercial modified live virus(MLV)vaccines provided good protection against HP-PRRSV.However,it could not provide sufficient protection against the novel strain SXYL1806.To explore the reasons for this phenomenon,we compared the genomic homology between the MLV strain and HP-PRRSV or NADC30-like PRRSV and found that the MLV strain had a lower genome similarity with NADC30-like PRRSV.Serum neutralization assay showed that MLV-immune serum slightly promoted the homologous HP-PRRSV replication and significantly promoted the heterologous NADC30-like PRRSV strain replication in vitro,suggesting that antibody-dependent enhancement(ADE)might also play a role in decreasing MLV protective efficacy.These findings expand our understanding of the potential factors affecting the protective effect of PRRSV MLV vaccines against the NADC30-like strains.

Identification of African swine fever virus MGF505-2R as a potent inhibitor of innate immunity in vitro

African swine fever(ASF)is etiologically an acute,highly contagious and hemorrhagic disease caused by African swine fever virus(ASFV).Due to its genetic variation and phenotypic diversity,until now,no efficient commercial vaccines or therapeutic options are available.The ASFV genome contains a conserved middle region and two flexible ends that code for five multigene families(MGFs),while the biological functions of the MGFs are not fully characterized.Here,ASFV MGF505-2R-deficient mutant ASFV-Δ2R was constructed based on a highly virulent genotype II field isolate ASFV CN/GS/2018 currently circulating in China.Transcriptomic profiling demonstrated that ASFV-Δ2R was capable of inducing a larger number of differentially expressed genes(DEGs)compared with ASFV CN/GS/2018.Hierarchical clustering of up-regulated DEGs revealed that ASFV-Δ2R induced the most dramatic expression of interferon-related genes and inflammatory and innate immune genes,as further validated by RT-qPCR.The GO and KEGG pathway analysis identified significantly enriched pathways involved in pathogen recognition and innate antiviral immunity.Conversely,pharmacological activation of those antiviral immune responses by exogenous cytokines,including type I/II IFNs,TNF-αand IL-1β,exerted combinatory effects and synergized in antiviral capacity against ASFV replication.Collectively,MGF505-2R is a newly identified inhibitor of innate immunity potentially implicated in immune evasion.

The Distribution of Different Clades of Seneca Valley Viruses in Guangdong Province,China

Seneca Valley virus (SVV), a newly determined etiological agent of vesicular disease in swine, causes porcine idiopathic disease and occasional acute death in piglets. Recently, an increased number of SVV infection cases have been reported in the United States (US) and China, resulting in significant economic losses to the swine industry. The first identification of SVV in China was reported in Guangdong Province, a major swine producing province. The cases of SVV were continuously reported in Guangdong in 2015 and 2016. However, the spread of SVV in Guangdong in 2017 remains unknown.In this study, we determined two new SVV strains, CH-GD-2017-1 and CH-GD-2017-2, from Guangdong. The genetic analysis suggested that the two Guangdong strains showed different characteristics to previous Guangdong strains. They showed lower nucleotide similarity with strains isolated in 2015 and 2016, and were more similar to the US strains.Phylogenetic analyses indicated that the new strains were clustered in a different clade with previous Guangdong strains.We found 28 mutated amino acids in the new strains, compared with the first Guangdong strain, SVV CH-01-2015. In the geographic analysis, we found that the US and China reported more SVV cases than other countries, and most of the SVV cases were reported in east and central China—of which, Guangdong Province is one of the major epidemic regions. In conclusion, our findings indicate that SVV continued to spread in Guangdong Province in 2017, and two different clades of SVVs have emerged in this region.

The DEAD-Box RNA Helicase DDX1 Interacts with the Viral Protein 3D and Inhibits Foot-and-Mouth Disease Virus Replication

Foot-and-mouth disease virus(FMDV)can infect domestic and wild cloven-hoofed animals.The non-structural protein 3D plays an important role in FMDV replication and pathogenesis.However,the interaction partners of 3D,and the effects of those interactions on FMDV replication,remain incompletely elucidated.In the present study,using the yeast two-hybrid system,we identified a porcine cell protein,DEAD-box RNA helicase 1(DDX1),which interacted with FMDV 3D.The DDX1-3D interaction was further confirmed by co-immunoprecipitation experiments and an indirect immunofluorescence assay(IFA)in porcine kidney 15(PK-15)cells.DDX1 was reported to either inhibit or facilitate viral replication and regulate host innate immune responses.However,the roles of DDX1 during FMDV infection remain unclear.Our results revealed that DDX1 inhibited FMDV replication in an ATPase/helicase activity-dependent manner.In addition,DDX1 stimulated IFN-p activation in FMDV-infected cells.Together,our results expand the body of knowledge regarding the role of DDX1 in FMDV infection.

African Swine Fever Virus MGF-110-9L-deficient Mutant Has Attenuated Virulence in Pigs

African swine fever virus(ASFV)is the etiological agent of African swine fever(ASF),an often lethal disease in domestic and wild pigs.ASF represents a major threat to the swine industry worldwide.Currently,no commercial vaccine is available because of the complexity of ASFV or biosecurity concerns.Live attenuated viruses that are naturally isolated or genetically manipulated have demonstrated reliable protection against homologous ASFV strain challenge.In the present study,a mutant ASFV strain with the deletion of ASFV MGF-110-9L(ASFV-D9L)was generated from a highly virulent ASFV CN/GS/2018 parental strain,a genotypeⅡASFV.Relative to the parental ASFV isolate,deletion of the MGF-110-9L gene significantly decreased the ability of ASFV-D9L to replicate in vitro in primary swine macrophage cell cultures.The majority of animals inoculated intramuscularly with a low dose of ASFV-D9L(10 HAD50)remained clinically normal during the 21-day observational period.Three of five ASFV-D9L-infected animals displayed low viremia titers and low virus shedding and developed a strong virus-specific antibody response,indicating partial attenuation of the ASFV-D9L strain in pigs.The findings imply the potential usefulness of the ASFV-D9L strain for further development of ASF control measures.

组织蛋白酶S抑制塞内卡病毒在IBRS-2细胞中的复制

【目的】本研究旨在探究猪源组织蛋白酶S(cathepsinS,CTSS)对塞内卡病毒(SenecaValley virus,SVV)复制的影响。【方法】SVV感染IBRS-2细胞,采用RT-qPCR在转录水平探究SVV感染对内源性CTSS表达的调控;采用ELISA测定SVV感染对CTSS酶活性的影响;通过Western blotting(WB)和RT-qPCR检测过表达CTSS对SVV复制及SVV诱导的抗病毒细胞因子的调控作用;合成针对CTSS的特异性siRNA,利用WB和RT-qPCR检测siRNA对CTSS的干扰效果以及CTSS被干扰后对SVV复制的影响。【结果】结果表明SVV感染IBRS-2细胞能显著上调内源性CTSS表达并增强CTSS酶活性;过表达CTSS能显著抑制SVV在IBRS-2细胞中的复制,同时促进宿主抗病毒细胞因子的表达;siRNA-2947下调内源性CTSS表达进而促进SVV复制。【结论】CTSS通过增强宿主抗病毒细胞因子上调表达而抑制SVV复制,本研究为进一步深入探究宿主CTSS在抗SVV免疫应答中的作用及机制提供参考依据。

FoxJ1 inhibits African swine fever virus replication and viral S273R protein decreases the expression of FoxJ1 to impair its antiviral effect

African swine fever(ASF)is a highly pathogenic swine infectious disease that affects domestic pigs and wild boar,which is caused by the African swine fever virus(ASFV).ASF has caused huge economic losses to the pig industry and seriously threatens global food security and livestock health.To date,there is no safe and effective commercial vaccine against ASF.Unveiling the underlying mechanisms of ASFV-host interplay is critical for developing effective vaccines and drugs against ASFV.In the present study,RNA-sequencing,RT-qPCR and Western blotting analysis revealed that the transcriptional and protein levels of the host factor FoxJ1 were significantly down-regulated in primary porcine alveolar macrophages(PAMs)infected by ASFV.RT-qPCR analysis showed that overexpression of FoxJ1 upregulated the transcription of type I interferon and interferon stimulating genes(ISGs)induced by poly(dA:dT).FoxJ1 revealed a function to positively regulate innate immune response,therefore,suppressing the replication of ASFV.In addition,Western blotting analysis indicated that FoxJ1 degraded ASFV MGF505-2R and E165R proteins through autophagy pathway.Meanwhile,RT-qPCR and Western blotting analysis showed that ASFV S273R inhibited the expression of FoxJ1.Altogether,we determined that FoxJ1 plays an antiviral role against ASFV replication,and ASFV protein impairs FoxJ1-mediated antiviral effect by degradation of FoxJ1.Our findings provide new insights into the antiviral function of FoxJ1,which might help design antiviral drugs or vaccines against ASFV infection.

Differential gene expression in porcine SK6 cells infected with wild-type and SAP domain-mutant foot-and-mouth disease virus

Foot-and-mouth disease virus(FMDV) is the causative agent of a highly contagious disease in livestock. The viral proteinaseL^(rop) of FMDV is involved in pathogenicity, and mutation of theL^(rop) SAP domain reduces FMDV pathogenicity in pigs. To determine the gene expression profiles associated with decreased pathogenicity in porcine cells, we performed transcriptome analysis using next-generation sequencing technology and compared differentially expressed genes in SK6 cells infected with FMDV containingL^(rop) with either a wild-type or mutated version of the SAP domain. This analysis yielded 1,853 genes that exhibited a ≥ 2-fold change in expression and was validated by real-time quantitative PCR detection of several differentially expressed genes. Many of the differentially expressed genes correlated with antiviral responses corresponded to genes associated with transcription factors, immune regulation, cytokine production, inflammatory response, and apoptosis. Alterations in gene expression profiles may be responsible for the variations in pathogenicity observed between the two FMDV variants. Our results provided genes of interest for the further study of antiviral pathways and pathogenic mechanisms related to FMDV L^(rop).

Porcine Picornavirus 3C Protease Degrades PRDX6 to Impair PRDX6-mediated Antiviral Function

Peroxiredoxin-6(PRDX6)is an antioxidant enzyme with both the activities of peroxidase and phospholipase A2(PLA2),which is involved in regulation of many cellular reactions.However,the function of PRDX6 during virus infection remains unknown.In this study,we found that the abundance of PRDX6 protein was dramatically decreased in foot-and-mouth disease virus(FMDV)infected cells.Overexpression of PRDX6 inhibited FMDV replication.In contrast,knockdown of PRDX6 expression promoted FMDV replication,suggesting an antiviral role of PRDX6.To explore whether the activity of peroxidase and PLA2 was associated with PRDX6-mediated antiviral function,a specific inhibitor of PLA2(MJ33)and a specific inhibitor of peroxidase activity(mercaptosuccinate)were used to treat the cells before FMDV infection.The results showed that incubation of MJ33 but not mercaptosuccinate promoted FMDV replication.Meanwhile,overexpression of PRDX6 slightly enhanced type I interferon signaling.We further determined that the viral 3Cprowas responsible for degradation of PRDX6,and 3Cpro-induced reduction of PRDX6 was independent of the proteasome,lysosome,and caspase pathways.The protease activity of 3Cprowas required for induction of PRDX6 reduction.Besides,PRDX6 suppressed the replication of another porcine picornavirus Senecavirus A(SVA),and the 3Cproof SVA induced the reduction of PRDX6 through its proteolytic activity as well.Together,our results suggested that PRDX6 plays an important antiviral role during porcine picornavirus infection,and the viral 3Cproinduces the degradation of PRDX6 to overcome PRDX6-mediated antiviral function.

Foot-and-Mouth Disease Virus Inhibits RIP2 Protein Expression to Promote Viral Replication

Receptors interaction protein 2(RIP2)is a specific adaptor molecule in the downstream of NOD2.The role of RIP2 during foot-and-mouth disease virus(FMDV)infection remains unknown.Here,our results showed that RIP2 inhibited FMDV replication and played an important role in the activation of IFN-βand NF-κB signal pathways during FMDV infection.FMDV infection triggered RIP2 transcription,while it reduced the expression of RIP2 protein.Detailed analysis showed that FMDV 2B,2C,3C^(pro),and L^(pro) proteins were responsible for inducing the reduction of RIP2 protein.3C^(pro) and L^(pro) are viral proteinases that can induce the cleavage or reduction of many host proteins and block host protein synthesis.The carboxyl terminal 105-C114 and 135-C144 regions of 2B were essential for reduction of RIP2.Our results also showed that the N terminal 1-61 region of 2C were essential for the reduction of RIP2.The 2C-induced reduction of RIP2 was dependent on inducing the reduction of poly(A)-binding protein 1(PABPC1).The interaction between RIP2 and 2C was observed in the context of viral infection,and the residues 1-61 were required for the interaction.These data clarify novel mechanisms of reduction of RIP2 mediated by FMDV.

Correction to: Porcine Picornavirus 3C Protease Degrades PRDX6 to Impair PRDX6-mediated Antiviral Function

Correction to:Virologica Sinica(2021)36:948-957 https://doi.org/10.1007/s12250-021-00352-4 Due to our negligence,the original version of this article,published online on March 15,2021,contained a mistake in Figure 2E(The Knockdown band of Western blotting was provided incorrectly).The correct Fig.2E is given below.We apologize for this error and state that this does not change the scientific conclusions of the article in any way.