When eukaryotic cells are undergoing stimulations like oxidative stress,heat shock,or vi-ral infection,cellular stress response will quickly initiate to stop translation,leading to the produc-tion of a large number of stress granules(SGs).SGs,as dynamic membraneless protein-RNA ag-gregates,play an important role in maintaining cellular homeostasis and regulating host gene ex-pression.Upon viral invasion,the host halts translation to form SGs,thereby arresting the transla-tion of viral proteins within host cells.This process recruits innate immune-related host factors,limiting the virus from exploiting host translation machinery to complete its life cycle.It activates the innate immune pathway.However,some viruses have evolved multiple mechanisms to counter SGs,in order to provide a better intracellular environment for viral replication.Here,we review the generation of SGs,antiviral mechanism of SGs,and the strategies for escaping SGs during virus e-volution,in order to provide a new perspective for the development of antiviral drugs.

Coronavirus infection can cause serious respiratory and digestive system diseases in hu-mans and animals.In recent years,the frequent outbreaks and newly outbreaks of coronavirus in-fection have threatened global public health and the development of livestock and poultry.Howev-er,the development of anti-coronavirus drugs and vaccines was restricted due to the insufficient understanding of the mechanisms of coronavirus pathogenesis and cross species transmission.Re-verse genetic manipulation technology is a powerful tool in virological research,which can be used for the study of pathogenesis mechanisms,replication mechanisms and function analysis of protein.It is also be used in the development of attenuated or gene labeled vaccines,and antiviral drugs.Due to the large genome and complex structure of the coronavirus,the reverse genetic manipulation technology of coronavirus has been lagging for a long time.With the continuous updating of molec-ular biology methods,various new construction strategies have emerged.This article focuses on the construction strategy of the reverse genetic operating system for coronavirus,as well as its applica-tion in virus transmission and pathogenic mechanisms,and development of vaccines,which will provide favorable tools for the prevention and control of the coronavirus infection.

Porcine parvovirus(PPV)is a causative agent of porcine parvovirus infection(PPI),which significantly impacts the pig industry due to its association with reproductive dysfunction.The condition is characterized by stillbirth,mummified fetuses,fetal weakness,and abortion in pregnant sows.The pathogenic mechanism remains incompletely understood,with no effective therapeutic drugs available currently.Despite extensive research on the host's response to PPV in-fection and identification of various signaling pathway transduction mechanisms,a comprehensive understanding is still lacking.This review aims to summarize the current knowledge regarding al-terations in related signaling pathways following PPV infection,provide novel insights into the pathogenesis of PPV and facilitate the drug development.

Hepatitis E virus(HEV)is one of the most common pathogens in acute viral hepatitis.There are at least eight distinct genotypes of HEV.Only humans can contract HEV genotypes 1 and 2,but zoonotic viruses like genotypes 3 and 4 are mostly spread by eating undercooked or in-fected pork in some affluent nations.As a result,boars,both domestic and wild,are typically regar-ded as primary hosts of HEV.Nevertheless,during the past few years,a growing body of research has demonstrated that a number of other wild ruminant animals,such as wild deer and goats,are also susceptible to HEV infection.Determining their participation in the epidemiological cycle of hepatitis E thus requires an understanding of the risk variables that influence the transmission be-tween wild ruminants and humans.With an emphasis on published serological and molecular re-search,this review offers a broad summary of the body of knowledge currently available on the epi-demiology of HEV in wild ruminants.It addresses potential risk factors that could impact the spread of HEV among animals as well as their potential to serve as a source of infectious zoonotic illnesses.It presents an overview of the most recent developments in the epidemiology of HEV in wild ruminants and offers a framework for HEV prevention and management based on science.

Porcine deltacoronavirus(PDCoV),a newly discovered virus in recent years,can cause severe diarrhea,vomiting,dehydration and even death in piglets.S protein is an important structur-al protein of PDCoV,which determines the host or tissue tropism of the virus,and is an important target for the development of PDCoV vaccines and detection methods.In order to prepare mono-clonal antibody(MAb)against the S protein of PDCoV,the recombinant plasmid of S protein was constructed based on the extracellular domain sequence of S protein of PDCoV epidemic strain in China and transformed into DH10Bac competent cells.The recombinant bacmid was identified by blue-white spot screening and PCR.BALB/c mice were immunized with S protein,and the spleen cells of immunized mice were fused with myeloma cells.The positive hybridoma cells that secreted stable antibodies were screened by indirect ELISA and subcloning.Five hybridoma cell superna-tants(MAb)specifically recognizing S protein(2E5,4D5,5D10,2F7 and 5A9)were identified by Western blot and immunofluorescence assay(IFA).Subsequently,the neutralization test showed that three of the monoclonal antibodies(2E5,4D5 and 5D10)could neutralize the virus to varying degrees.The S protein was successfully expressed and 5 monoclonal antibodies that can stably se-crete and specifically bind to PDCoV and S protein were prepared,which laid an important founda-tion for further research on the structure and function of S protein,the development of detection methods for PDCoV infection,and the prevention or treatment of PDCoV infection.

In order to develop a positive quality control products for the detection of porcine repro-ductive and respiratory syndrome virus(PRRSV)nucleic acid by real-time fluorescent quantitative PCR(RT-qPCR),the positive quality control products of PRRSV-1 and PRRSV-2 M genes were prepared using armored RNA technology of MS2 phage.PRRSV-1 and PRRSV-2 M genes were amplified,purified and recovered,and ligated into pET28b vector containing MS2 mature enzyme protein gene and capsid protein.After transformed into BL21(DE3),the gene products were in-duced by IPTG and purified by PEG6000 precipitation method to prepare the armored RNA virus-like particles(AR-PRRSV)containing PRRSV M gene.Following the performance evaluation,as the positive quality control products of PRRSV-1 and PRRSV-2 M genes,AR-PRRSV1M and AR-PRRSV2M were calculated using YY/T 1652-2019 standard.Results showed that it had a good u-niformity,stable storage for the armored virus-like particles at-20,4,25 ℃ for 60 d,and 37 ℃ for 30 d.The prepared armored virus-like particles AR-PRRSV1M and AR-PRRSV2M were deter-mined by digital quantitative PCR(ddPCR)after preliminary quantification by RT-qPCR.The 104 copies/μL of AR-PRRSV1M and AR-PRRSV2M ddPCR fixation was(1.33+0.50)× 104 cop-ies/μL.The above results indicates that the AR-PRRSVM can be used as the quality control of the whole detection process(nucleic acid extraction,reverse transcription and RT-qPCR).

To investigate the role of the nucleotide-binding domain and leucine-rich-repeat-contai-ning family member X1(NLRX1)in the replication of Newcastle disease virus(NDV),the ex-pression level of NLRX1 was examined following infection of 10-day-old specific pathogen-free(SPF)chicks and HD11 cells with the NDV NA-1 strain.Additionally,the proliferation of NDV,the expression of pro-inflammatory cytokines in HD11 cells,and the oxidative stress status were e-valuated in the presence of either overexpressed or underexpressed NLRX1.The results demonstra-ted that NA-1 infection led to an increase in NLRX1 expression both in vivo and in vitro.Further-more,overexpression of NLRX1 inhibited viral proliferation,enhanced the expression of cellularIL-1β,IL-6,and IFN-β,without affecting levels of autophagy or apoptotic cells.However,NLRX1 elevation resulted in elevated mRNA levels of iNOS,Keap1,Nrf2,NQO1,and HO-1 within 24 h.In conclusion,NLRX1 suppresses NDV proliferation by promoting early ROS production.

Quantitative analysis of UL35 and gB genes at different time points after PRV infection showed that there were significant differences between the two at 2.5,5.0 and 20.0 h after infec-tion,and the expression of UL35 gene could be observed in the early stage of PRV infection.To de-termine whether the UL 35 gene can be used as a target for the diagnosis of PRV infection,a spe-cific primer pair was designed and synthesized according to the conserved sequence of the UL35 gene of different PRV strains,and used to amplify a fragment of 54 bp in length.After optimizing the reaction conditions and system,the standard curve for the established by SYBR Green Ⅰ real-time PCR detection method showed that it had good repeatability,specificity and a good linear rela-tionship to the template concentration.No amplifications for porcine reproductive and respiratory syndrome virus(PRRSV),classical swine fever virus(CSFV),and African swine fever virus(AS-FV)were detected.Compared with the existing similar methods,the established method showed no difference in sensitivity.The coefficient of variation of inter-and intra-group repeatability for the method was less than 2％.Detection of the samples in mice challenged with PRV revealed a certain amount of viral load in tissue.The results showed that UL35 gene can be used as a target for the diagnosis of PRV infection.

This study aims to obtain two whole-genome sequences of enzootic nasal tumor virus of goats(ENTV-2)from Anhui Province and analyzed the genetic diversity of ENTV-2 gene.Nasal secretion samples and blood samples of six goats with enzootic nasal adenocarcinoma(ENA)were collected from a goat farm in Anhui Province.The total RNA was extracted by the TRIzol method.The DNA interference was removed by the two-step reverse transcription.The ENTV-2 was detec-ted by PCR.Then,two positive samples were selected and five pairs of primers were used to ampli-fy the whole-genome sequences of ENTV-2.After sequencing and splicing,two sequences were up-loaded to the database for comparative analysis with the sequences in the NCBI database.Finally,the genetic evolution tree was constructed.ENTV-2 was detected in the nasal secretion samples,but not in the blood of the six ENA goats.The ENTV-2 genes were approximately 7 400 bp in length,named ENTV-2AH1(DDBJ accession no.:LC762616)and ENTV-2AH2(DDBJ accession no.:LC762617),respectively.Two sequences showed 99.2％and 99.1％homology with the Fujian strain(ENTV-2FJ)and Guangxi strain(ENTV-2-DA0),respectively.They were in the same evo-lutionary branch.In this study,two whole-genome sequences of ENTV-2 were obtained in Anhui for the first time,which can help to further study the genetic diversity of ENTV-2 in China.

A recombinant enzyme-mediated nucleic acid amplification(RAA)technology combined with colloidal gold test strips was developed for the rapid detection of bovine enterovirus(BEV).Using the highly conserved BEV 5'UTR as the target sequence,the primers were designed and screened.Downstream primer labeled with biotin at the 5'end and the probe labeled with 6-FAM at the 5'end were used to establish the RT-RAA method.The test strips were assembled by using mouse-derived anti-6-FAM monoclonal antibody as the gold standard antibody,with a streptavidin encapsulated in the detection line and sheep anti-mouse IgG encapsulated in the quality control line.A RT-RAA-LFD method was established by combing RAA technique with the prepared later-al flow device test strips for the detection of bovine enterovirus nucleic acids.The specificity,sensi-tivity,repeatability,and clinical application of the method are also evaluated.The results showed that the optimal primer concentration of this method was 5 μmol/L,and the amplification of BEV nucleic acids was accomplished by reacting at 35 ℃ for 8 min with the lowest detection limit of 101 copies/μL.No cross-reactivity with bovine viral diarrhea virus,bovine parvovirus,and foot-and-mouth disease virus was observed.The efficacy for the prepared test strips was at least for 90 d kept at 4 ℃.Detection of 74 clinical samples yielded a similar result compared with RT-PCR method.The above results demonstrated that the BEV RT-RAA-LFD method established in this study has high sensitivity,specificity,and more convenient to use,which is suitable for clinical de-tection on-site and provides a new technical tool for the diagnosis and epidemiological investigation of BEV infection.