Identification of monoclonal antibody targeting epitope on p72 trimeric spike of African swine fever virus.

African swine fever virus (ASFV) is highly contagious and can cause lethal disease in pigs. ASFV p72 protein is a major capsid protein that presents as trimer in the virion. Epitopes on the surface of p72 trimer are considered as protective antigens. In this study, recombinant p72 protein and p72-baculovirus were constructed and obtained. Three monoclonal antibodies (mAbs) specific to ASFV p72 protein, designated as 1A3, 2B5 and 4A5, were generated. Among them, 4A5 showed strong reactivity with ASFV infected cells. Subsequently, the epitope recognized by 4A5 was mapped and identified using a series of overlapping peptides generated from p72 protein. IFA and western blot analyses showed that 4A5 recognized the linear epitope of p72 monomer located between amino acids 245-285 and recognized the conformational epitope located at the surface and top of the p72 trimer. These findings will enrich our knowledge regarding the epitope on p72 protein and provide valuable information for further characterization of the antigenicity and molecular functions of p72 protein.

Characterization and phylogenetic analysis of bovine gammaherpesvirus 4 isolated in China, 2022.

Bovine gammaherpesvirus 4 (BoHV-4) is a common virus detected in bovine with respiratory disease worldwide. In this study, we identified and characterized a novel BoHV-4 strain, referred as HB-ZJK, in vaginal swabs collected from cattle in China, 2022. The long unique region (LUR) of HB-ZJK is 10,9811 bp in length. It shares 99.17% to 99.38% nucleotide identity to five BoHV-4 strains available in GenBank and the highest similarity was seen with BoHV-4V. test (JN133502.1) strain (99.38%). Mutations, insertions or deletions were observed mainly in HB-ZJK gB (ORF8), TK (ORF21), gH (ORF22), MCP (ORF25), PK (ORF36), gM (ORF39), and gL (ORF47) genes compared to its genomic coordinates. Phylogenetic analyses of gB and TK genes showed that HB-ZJK clustered with China 512 (2019), B6010 (2009), and J4034 (2009) strains, demonstrating that the isolated HB-ZJK belongs to genotype 1. This is the first report that has revealed a comprehensive genome profile of BoHV-4 strain in China. This study will provide foundation for epidemiological investigations of BoHV-4 and contribute to the molecular and pathogenic studies of BoHV-4.

Porcine epidemic diarrhea virus ORF3 protein causes endoplasmic reticulum stress to facilitate autophagy.

Porcine epidemic diarrhea virus (PEDV), the causative agent of PED, is an enveloped, positive-stranded RNA virus in the genus Alphacoronavirus, family Coronaviridae, order Nidovirales. PEDV non-structural accessory protein ORF3 is an ion channel related to viral infectivity and pathogenicity. Our previous study showed that PEDV ORF3 has expression characteristic of aggregation in cytoplasm, but its biological function remains elusive. Thus in this study, we initiated the construction of various vectors to express ORF3, and found ORF3 localized in the cytoplasm in the aggregation manner. Subsequently, confocal microscopy analysis showed that the aggregated ORF3 localized in endoplasmic reticulum (ER) to trigger ER stress response via up-regulation of GRP78 protein expression and activation of PERK-eIF2α signaling pathway. In addition, our results showed that PEDV ORF3 could induce the autophagy through inducing conversion of LC3-I to LC3-II, but couldn't influence the apoptosis. In contrast, conversion of LC3-I/LC3-II could be significantly inhibited by 4-PBA, an ER stress inhibitor, indicating that ORF3-induced autophagy is dependent on ER stress response. This work not only provides some new findings for the biological function of the PEDV ORF3 protein, but also help us for the further understanding the molecular interaction between PEDV ORF3 protein and cells.