Porcine sapelovirus (PSV) is an important emerging pathogen associated with a wide variety of diseases in swine, including acute diarrhoea, respiratory distress, skin lesions, severe neurological disorders, and reproductive failure. Although PSV is widespread, serological assays for field-based epidemiological studies are not yet available. Here, four PSV strains were recovered from diarrheic piglets, and electron microscopy revealed virus particles with a diameter of ~32 nm. Analysis of the entire genome sequence revealed that the genomes of PSV isolates ranged 7569–7572 nucleotides in length. Phylogenetic analysis showed that the isolated viruses were classified together with strains from China. Additionally, monoclonal antibodies for the recombinant PSV-VP1 protein were developed to specifically detect PSV infection in cells, and we demonstrated that isolated PSVs could only replicate in cells of porcine origin. Using recombinant PSV-VP1 protein as the coating antigen, we developed an indirect ELISA for the first time for the detection of PSV antibodies in serum. A total of 516 swine serum samples were tested, and PSV positive rate was 79.3%. The virus isolates, monoclonal antibodies and indirect ELISA developed would be useful for further understanding the pathophysiology of PSV, developing new diagnostic assays, and investigating the epidemiology of the PSV.

Introduction: Muscovy duck parvovirus (MDPV), Goose parvovirus (GPV), Duck circovirus, (DuCV) and Duck adenovirus 3 (DAdV-3) are important pathogens that cause high morbidity and mortality in ducks, causing huge economic loss for the duck industry.Methods: The present study, a quadruplex one-step real time quantitative PCR method for the detection of MDPV, GPV, DuCV, and DAdV-3 was developed. Results: The results showed that assay had no cross-reactivity with other poultry pathogens [Duck plague virus (DPV), Duck tembusu virus (DTMUV), H6 avian influenza virus (H6 AIV), New duck reovirus (NDRV), Newcastle disease virus (NDV), H4 avian influenza virus (H4 AIV), Escherichia coli (E. coli), Muscovy duck reovirus (MDRV), Egg drop syndrome virus (EDSV), Pasteurella multocida (P. multocida)]. The sensitivity result showed that the limits of detection for MDPV, GPV, DuCV, and DAdV-3 were 10, 10, 1 and 10 copies/µl, respectively; The coefficients of variation intra- and inter-method was 1-2%; The range of linear (109 to 103 copies/µL) demonstrated the R2 values for MDPV, GPV, DuCV, and DAdV-3 as 0.9975, 0.998, 0.9964, and 0.996, respectively. The quadruplex real time quantitative PCR method efficiency was 90.30%, 101.10%, 90.72%, and 90.57% for MDPV, GPV, DuCV, and DAdV-3, respectively. 396 clinical specimens collected in some duck sausages from June 2022 to July 2023 were simultaneously detected using the established quadruplex real time quantitative PCR method and the reported assays. The detection rates for MDPV, GPV, DuCV, and DAdV-3 were 8.33% (33/396), 17.93% (71/396), 33.58% (133/396), and 29.04% (115/396), respectively. The agreement between these assays was greater than 99.56%.Discussion: The developed quadruplex real-time quantitative PCR assay can accurately detect these four viruses infecting ducks, providing a rapid, sensitive, specific and accurate technique for clinical testing.

Background: Feline panleukopenia, feline calicivirus infection, feline viral rhinotracheitis, and feline infectious peritonitis are significant diseases that threaten feline health. The trend of mixed infections is increasing, and current diagnostic methods are limited in scope and unable to provide rapid, simultaneous detection of these diseases.Methods: Four groups of primers and probes targeting the VP2 gene of Feline Panleukopenia virus (FPV), the TK gene of Feline Herpesvirus (FHV-1), the ORF2 gene of Feline Calicivirus (FCV), and the N gene of Feline Infectious Peritonitis Virus (FIPV) were designed. After optimizing the concentrations of primers and probes and annealing temperature, a quadruplex TaqMan MGB fluorescent quantitative PCR method was established to concurrently detect these four pathogens. Recombinant plasmid standards were constructed to establish standard curves, and the sensitivity, specificity, reproducibility, and clinical application of the assay were evaluated.Results: The optimal final concentrations of primers for FPV, FHV-1, FCV, and FIPV were 0.08, 0.04, 0.06, and 0.12 μM, respectively, and the optimal final concentrations of probes were 0.08, 0.08, 0.12, and 0.12 μM, respectively. The best annealing temperature was 59°C. No cross-reaction was observed with common pathogens in infected cats. The minimal detection limits for recombinant plasmids of T-VP2, T-TK, T-ORF2, and T-N were 50.79, 53.21, 47.91 and 41.25 copies/μL, respectively. The R² values of standard curves are 0.994, 1.0, 0.998 and 0.999, respectively, and high amplification efficiencies of 105.05%, 96.28%, 98.82%, and 96.45%, respectively. The coefficient of variation for inter-batch and intra-batch tests ranged from 0.14 to 1.37%. Among 381 fecal samples from cats, the detection rates for FPV, FHV-1, FCV, and FIPV were 13.65% (52/381), 18.37% (70/381), 26.77% (102/381), and 9.71% (37/381), respectively, with a 100% agreement with previously reported methods and commercial kits.Conclusion: The sensitive, specific, high-throughput, quadruplex TaqMan MGB quantitative fluorescent quantitative PCR method was successfully established for the simultaneous detection of FPV, FHV-1, FCV, and FIPV.

Porcine reproductive and respiratory syndrome virus (PRRSV), a member of the Arteriviridae family, represents a persistent menace to the global pig industry, causing reproductive failure and respiratory disease in pigs. In this study, we delved into the role of histone deacetylases (HDAC2) during PRRSV infection. Our findings revealed that HDAC2 expression is downregulated upon PRRSV infection. Notably, suppressing HDAC2 activity through specific small interfering RNA led to an increase in virus production, whereas overexpressing HDAC2 effectively inhibited PRRSV replication by boosting the expression of IFN-regulated antiviral molecules. Furthermore, we identified the virus’s nonstructural protein 11 (nsp11) as a key player in reducing HDAC2 levels. Mutagenic analyses of PRRSV nsp11 revealed that its antagonistic effect on the antiviral activity of HDAC2 is dependent on its endonuclease activity. In summary, our research uncovered a novel immune evasion mechanism employed by PRRSV, providing crucial insights into the pathogenesis of this virus and guiding the development of innovative prevention strategies against PRRSV infection.

Swine viruses like porcine sapovirus (SaV), porcine encephalomyocarditis virus (EMCV), porcine rotavirus A (RVA) and porcine astroviruses (AstV) are potentially zoonotic viruses or suspected of potential zoonosis. These viruses have been detected in pigs with or without clinical signs and often occur as coinfections. Despite the potential public health risks, no assay for detecting them all at once has been developed. Hence, in this study, a multiplex RT-PCR (mRT-PCR) assay was developed for the simultaneous detection of SaV, EMCV, RVA and AstV from swine fecal samples. The PCR parameters were optimized using specific primers for each target virus. The assay’s sensitivity, specificity, reproducibility, and application to field samples have been evaluated. Using a pool of plasmids containing the respective viral target fragments as a template, the developed mRT-PCR successfully detected 2.5 × 10³ copies of each target virus. The assay’s specificity was tested using six other swine viruses as a template and did not show any cross-reactivity. A total of 280 field samples were tested with the developed mRT-PCR assay. Positive rates for SaV, EMCV, RVA, and AstV were found to be 24.6% (69/280), 5% (14/280), 4.3% (12/280), and 17.5% (49/280), respectively. Compared to performing separate assays for each virus, this mRT-PCR assay is a simple, rapid, and cost-effective method for detecting mixed or single infections of SaV, EMCV, RVA, and AstV.