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Porcine epidemic diarrhea virus (PEDV) causes diarrhea and vomiting in piglets, leading to a mortality rate of 100%. Due to the high frequency of mutation, it is important to monitor the evolution of PEDV and develop potential vaccine candidates. In this study, two PEDV strains (ZJ2022 and ZQ2022) were identified by PCR. These strains were subsequently isolated, and their genome sequences, growth characteristics, and pathogenicity were compared. Phylogenetic and recombination analyses revealed that both strains belonged to GIIa-subgroup, and ZQ2022 was identified as a recombinant strain derived from ZJ2022. Further sequence analysis showed that the ZJ2022 strain had a modified top region of the S1 protein due to a three amino acid insertion (T380_Y380insGGE) in the S1 gene. According to the virus growth curve, ZJ2022 exhibited better cellular adaptation than ZQ2022, with higher viral titers from 8 hpi to 24 hpi. Additionally, ZQ2022 exhibited a high level of pathogenicity, causing severe diarrhea in piglets at 36 hpi and a 100% mortality rate by 96 hpi. In contrast, ZJ2022 showed lower pathogenicity, inducing severe diarrhea in piglets at 60 hpi, with a mortality rate of 60% at 96 hpi and 100% at 120 hpi. In summary, our findings provided evidence of the undergoing mutations in Chinese PEDV strains. Furthermore, the S gene insertion strain ZJ2022 exhibited strong cellular adaptability and low pathogenicity, making it a potential candidate strain for vaccine development.

Avian metapneumovirus (aMPV) represents a significant threat to the poultry industry, exhibiting a high degree of genetic diversity. Of these, the aMPV types A (aMPV-A), B (aMPV-B) and C (aMPV-C) are frequently detected in Chinese waterfowl and live poultry markets. Therefore, the rapid and accurate identification of these subtypes is of paramount importance in order to halt the spread of the disease. In this study, we have developed a multiplex real-time PCR assay endowed with the capacity to simultaneously discriminate aMPV-A, aMPV-B, and aMPV-C. This method demonstrates remarkable specificity, selectively amplifying aMPV-A, aMPV-B, and aMPV-C without cross-reactivity with other common avian pathogens. Furthermore, this method exhibits high sensitivity, with a detection threshold of 8.5 × 10 2 copies/μL for aMPV-A, aMPV-B, and aMPV-C. Moreover, the assay demonstrates reproducibility, as evidenced by intra- and inter-assay variability, with a coefficient of variation between 0.21% and 1.91%. Additionally, the receiver operating characteristic (ROC) curve analysis demonstrated that the multiplex real-time PCR assay exhibited high specificity and sensitivity (100.0% and 100.0% for aMPV-A, 90.9% and 100.0% for aMPV-B, 100% and 96.8% for aMPV-C) when compared with the classical aMPV real-time RT-PCR. Analyses of field samples (n=105) using the multiplex real-time PCR assay indicated that 35.2% (37/105) of samples were positive for aMPV, of which 29.7% (11/37) for aMPV-A, 32.4% (12/37) for aMPV-B and 37.8% (14/37) for aMPV-C. These data demonstrated that the multiplex real-time PCR assay can be used for epidemiological investigations of tree subtypes of aMPV and that aMPV had been observed to exhibit a proclivity for multiple types of co-infection in the Zhejiang province of China., Competing Interests: Disclosures The authors declare that they have no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Limited information on the virome and bacterial community hampers our ability to discern systemic ecological risk factors that cause cattle diarrhea, which has become a pressing issue in the control of disease. A total of 110 viruses, 1,011 bacterial genera, and 322 complete viral genomes were identified from 70 sequencing samples mixed with 1,120 fecal samples from 58 farms in northeast China. For the diarrheic samples, the identified virome and bacterial community varied in terms of composition, abundance, diversity, and geographic distribution in relation to different disease-associated ecological factors; the abundance of identified viruses and bacteria was significantly correlated with the host factors of clinical status, cattle type, and age, and with environmental factors such as aquaculture model and geographical location ( P < 0.05); a significant interaction occurred between viruses and viruses, bacteria and bacteria, as well as between bacteria and viruses ( P < 0.05). The abundance of SMB53 , Butyrivibrio , Facklamia , Trichococcus , and Turicibacter was significantly correlated with the health status of cattle ( P < 0.05). The proportion of BRV, BCoV, BKV, BToV, BoNoV, BoNeV, BoAstV, BEV, BoPV, and BVDV in 1,120 fecal samples varied from 1.61% to 12.05%. A series of significant correlations were observed between the prevalence of individual viruses and the disease-associated ecological factors. A genome-based phylogenetic analysis revealed high variability of 10 bovine enteric viruses. The bovine hungarovirus was initially identified in both dairy and beef cattle in China. This study elucidates the fecal virome and bacterial community signatures of cattle affected by diarrhea, and reveals novel disease-associated ecological risk factors, including cattle type, cattle age, aquaculture model, and geographical location.IMPORTANCEThe lack of data on the virome and bacterial community restricts our capability to recognize ecological risk factors for bovine diarrhea disease, thereby hindering our overall comprehension of the disease's cause. In this study, we found that, for the diarrheal samples, the identified virome and bacterial community varied in terms of composition, abundance, diversity, configuration, and geographic distribution in relation to different disease-associated ecological factors. A series of significant correlations were observed between the prevalence of individual viruses and the disease-associated ecological factors. Our study aims to uncover novel ecological risk factors of bovine diarrheal disease by examining the pathogenic microorganism-host-environment disease ecology, thereby providing a new perspective on the control of bovine diarrheal diseases., Competing Interests: The authors declare no conflict of interest.