Porcine epidemic diarrhea (PED) is an acute, highly contagious, and infectious disease caused by porcine epidemic diarrhea virus (PEDV). PEDV can affect pigs of all ages, with 50~100% mortality in neonatal piglets and substantial economic losses in the swine industry. In the present study, 347 fecal and intestinal samples were collected from seven regions in China during 2020–2022. A comprehensive molecular investigation of the spike (S) gene of PEDV strains was carried out, which included phylogenetic analysis of the obtained PEDV sequences. Epidemiological surveillance data indicate that the GIIc subgroup strains are widely distributed among pigs. A PEDV strain was successfully isolated from positive small intestine samples and identified through RT-PCR detection using specific N gene primers of PEDV, indirect immunofluorescence assay (IFA), TEM analysis, genome sequencing, and full-length S gene analysis, named PEDV/SC/2022. RDP and SimPlot analysis showed that the isolate originated from the recombination of PEDV/AH2012 and PEDV/AJ1102. In conclusion, our findings contribute to the current understanding of PEDV epidemiology and provide valuable information for the control of PED outbreaks in China.

Canine coronavirus (CCoV) and feline coronavirus (FCoV) are endemic in companion animals. Due to their high mutation rates and tendencies of genome recombination, they pose potential threats to public health. The molecular characteristics and genetic variation of both CCoV and FCoV have been thoroughly studied, but their origin and evolutionary dynamics still require further assessment. In the present study, we applied a comprehensive approach and analyzed the S, M, and N genes of different CCoV/FCoV isolates. Discriminant analysis of principal components (DAPC) and phylogenetic analysis showed that the FCoV sequences from Chinese isolates were closely related to the FCoV clusters in Netherlands, while recombination analysis indicated that of S N-terminal domain (NTD) was the most susceptible region of mutation, and recombination of this region is an important cause of the emergence of new lineages. Natural selection showed that CCoV and FCoV subgenotypes were in selection constraints, and CCoV-IIb was in strong positive selection. Phylodynamics showed that the mean evolution rate of S1 genes of CCoV and FCoV was 1.281 × 10^–3 and 1.244 × 10^–3 subs/site/year, respectively, and the tMRCA of CCoV and FCoV was about 1901 and 1822, respectively. Taken together, our study centered on tracing the origin of CCoV/FCoV and provided ample insights into the phylogeny and evolution of canine and feline coronaviruses.

As a zoonotic virus, Japanese Encephalitis virus (JEV) poses a serious threat to human health and the breeding industry. Regarding the mechanism and complications of tissue inflammation caused by JEV, such as encephalitis and orchitis, there is no effective drug treatment currently, and the mechanism of occurrence has not been thoroughly studied. Therefore, it is necessary to study the mechanism of the inflammatory pathway caused by JEV. As one of the key proteins regulating cell death, BCL2 antagonist/killer (BAK) is also a necessary prerequisite for the release of cellular inflammatory factors. We found that after JEV infection, BAK-knockdown cells died less than normal cells, and the transcription levels of inflammatory factors such as TNF, IFNα, and IL-1β and their corresponding regulatory genes were also significantly reduced. By further verifying protein expression on the cell death pathway, it was found that pyroptotic activation and virus titer were also significantly reduced in BAK.KD cells, suggesting that JEV proliferation might be related to BAK-induced cell death. From our data, we could conclude that JEV utilized the BAK-promoted pyroptotic pathway to release more virions after the final Gasdermin D-N (GSDMD-N) protein pore formation for the purpose of JEV proliferation. Therefore, the study of the endogenous cell death activator protein BAK and the final release pathway of JEV, is expected to provide some new theoretical basis for future research on the screening of targeted drugs for the treatment of inflammatory diseases caused by JEV.

Pasteurella multocida, a zoonotic pathogen that produces a 146-kDa modular toxin (PMT), causes progressive atrophic rhinitis with severe turbinate bone degradation in pigs. However, its mechanism of cytotoxicity remains unclear. In this study, we expressed PMT, purified it in a prokaryotic expression system, and found that it killed PK15 cells. The host factor CXCL8 was significantly upregulated among the differentially expressed genes in a transcriptome sequencing analysis and qPCR verification. We constructed a CXCL8-knockout cell line with a CRISPR/Cas9 system and found that CXCL8 knockout significantly increased resistance to PMT-induced cell apoptosis. CXCL8 knockout impaired the cleavage efficiency of apoptosis-related proteins, including Caspase3, Caspase8, and PARP1, as demonstrated with Western blot. In conclusion, these findings establish that CXCL8 facilitates PMT-induced PK15 cell death, which involves apoptotic pathways; this observation documents that CXCL8 plays a key role in PMT-induced PK15 cell death.

In 2023, the detection rate of porcine rotavirus (PoRV) surpassed that of porcine epidemic diarrhea virus (PEDV) for the first time, establishing PoRV as the predominant pathogen responsible for viral diarrhea in pigs. To systematically investigate the epidemiology and molecular characteristics of PoRV in Southwest China, a total of 196 diarrheal clinical samples were collected from 29 large-scale pig farms across the region during 2024–2025. RT-qPCR results revealed a high PoRV positivity rate of 57.14% (112/196) with group A porcine rotavirus (PoRVA) being the most prevalent at 46.43%, representing the predominant group. Genotyping and phylogenetic analysis of the VP4 and VP7 genes indicated that the P genotype P[13] was most prevalent (77.78%, 21/27), while the major G genotypes were G4 (39.28%) and G9 (35.71%). The most common G/P combinations were G9P[13] and G4P[13]. Furthermore, a PoRV strain was successfully isolated and identified through whole-genome sequencing, indirect immunofluorescence assay (IFA), and transmission electron microscopy (TEM). The isolate was designated RVA/Pig-wt/SCLS-JW/2024/G1P[7], with a whole-genome constellation of G1-P[7]-I5-R1-C1-M1-A8-N1-T1-E1-H1. The structural proteins VP1-4 and VP6-7, along with nonstructural genes NSP1 and NSP5, shared high sequence identity with porcine strains, whereas the nonstructural genes NSP2–NSP4 clustered more closely with human rotaviruses. These findings indicate a higher prevalence of PoRV in southwestern China compared to other regions; the dominant circulating genotypes have shifted to G9 and G4; the isolated G1P[7] strain is relatively rare in China and might be a genetic recombinant of human and porcine rotaviruses. This study provides valuable data and theoretical support for understanding the current epidemiology of PoRV, and facilitates vaccine development and the formulation of prevention and control strategies.

The well-being and subsistence of giant pandas, an endangered species with a limited distribution, are currently threatened by a number of viruses, including canine parvovirus (CPV-2), canine distemper virus (CDV), and giant panda rotavirus (GPRV). To allow for timely intervention upon viral infection, it is necessary to execute rapid and accurate diagnosis of potential mixed viral infections. In the present study, we developed and validated a multiplex PCR (mPCR) approach for the detection of CPV-2, CDV, and GPRV infections. The results indicate that the method could selectively amplify the three viruses with high sensitivity and specificity, which are necessary attributes in clinical settings. Utilizing the established method, (sub)clinical giant panda samples were examined, and CPV-2, CDV, and GPRV were found in 19.72% (43 out of 218), 7.34% (16 out of 218), and 6.42% (14 out of 218) of the samples, respectively. Noticeably, mixed infections of two or three viruses were common, and this was generally observed in CDV- or GPRV-positive samples. Meanwhile, mPCR results were further validated with sequencing and the phylogenetic analysis of full-length sequences of viral genes. Taken together, our study provides an approachable assay which enables the quick detection of the three viruses mentioned above, which will benefit clinical diagnosis and laboratory epidemiological-based investigations of the giant panda population.