(1) Background: Group A rotaviruses (RVAs) are the primary cause of severe intestinal diseases in piglets. Porcine rotaviruses (PoRVs) are widely prevalent in Chinese farms, resulting in significant economic losses to the livestock industry. However, isolation of PoRVs is challenging, and their pathogenicity in piglets is not well understood. (2) Methods: We conducted clinical testing on a farm in Jiangsu Province, China, and isolated PoRV by continuously passaging on MA104 cells. Subsequently, the pathogenicity of the isolated strain in piglets was investigated. The piglets of the PoRV-infection group were orally inoculated with 1 mL of 1.0 × 10⁶ TCID50 PoRV, whereas those of the mock-infection group were fed with an equivalent amount of DMEM. (3) Results: A G5P[23] genotype PoRV strain was successfully isolated from one of the positive samples and named RVA/Pig/China/JS/2023/G5P[23](JS). The genomic constellation of this strain was G5-P[23]-I5-R1-C1-M1-A8-N1-T1-E1-H1. Sequence analysis revealed that the genes VP3, VP7, NSP2, and NSP4 of the JS strain were closely related to human RVAs, whereas the remaining gene segments were closely related to porcine RVAs, indicating a reassortment between porcine and human strains. Furthermore, infection of 15-day-old piglets with the JS strain resulted in a diarrheal rate of 100% (8 of 8) and a mortality rate of 37.5% (3 of 8). (4) Conclusions: The isolated G5P[23] genotype rotavirus strain, which exhibited strong pathogenicity in piglets, may have resulted from recombination between porcine and human strains. It may serve as a potential candidate strain for developing vaccines, and its immunogenicity can be tested in future studies.

Background The circular replication-associated protein (Rep)-encoding single-stranded (CRESS) DNA virus emergence in diverse host has been associated with severe disease. Porcine circovirus-like virus (Po-Circo-like [PCL] virus) is a CRESS DNA virus, the prevalence and pathogenicity of which are rarely studied. Methods We obtained two blood samples, four faecal samples, and two intestinal samples from a pig farm suffered from diarrheal disease in the delivery room in September 2020 and attempted to isolate and identify a causative pathogen. Subsequently, only PCL virus was positive, and qRT-PCR was designed to detect the loading titre of PCL virus. We then initiated a heightened surveillance program on the pathogenicity and epidemiology of PCL virus. Results Six PCL virus strains, with severe diarrhoea and haemorrhagic enteritis, have been found in six different pig farms in Guangdong province, China. A multiple sequence alignment of these PCL viruses and bovine circovirus-like virus/CH showed a similarity of 92.5-94.8% for the Rep protein, indicating these PCL viruses are highly homologous to Bo-Circo-like virus associated with calf diarrhoea. There were striking similarities between the PCL virus and bovine circovirus-like virus outbreaks in aetiological settings and Genomic sequence. We found that 11.2% (20/178) of diarrhoea samples and 13.3% (6/45) of pig farms were positive for PCL virus, suggesting that PCL virus may have spread widely in Pig farms. Moreover, this article underscores the risk of PCL virus spilling over and adapting to new species. Conclusions Porcine circovirus-like virus was found to be associated with porcine diarrheal disease in China.

Porcine epidemic diarrhea virus (PEDV) is a highly contagious virus that causes severe diarrhea and high mortality in neonatal piglets. Current control measures, such as inactivated and live-attenuated vaccines, have limitations in providing complete protection. In this study, we evaluate the immunogenicity and protective efficacy of a PEDV S protein subunit vaccine compared to a traditional inactivated vaccine. Piglets and Sows were immunized with either the subunit vaccine or an inactivated vaccine, and serum samples were collected to assess IgG and neutralizing antibody levels. Results demonstrated that the S protein subunit vaccine induced significantly higher IgG and neutralizing antibody levels in both piglets and sows compared to the inactivated vaccine. Piglets born to immunized sows were challenged with a virulent PEDV strain. Piglets from the subunit vaccine group exhibited lower viral shedding, reduced clinical symptoms, and minimal intestinal lesions. These findings suggest that the PEDV S protein subunit vaccine provides enhanced immunity and protection against PEDV, making it a promising candidate for preventing PEDV infections in swine.

(1) Background: Group A rotaviruses (RVAs) are the primary cause of severe intestinal diseases in piglets. Porcine rotaviruses (PoRVs) are widely prevalent in Chinese farms, resulting in significant economic losses to the livestock industry. However, isolation of PoRVs is challenging, and their pathogenicity in piglets is not well understood. (2) Methods: We conduct clinical testing on a farm in Jiangsu Province, China, and isolate strains of porcine rotavirus by continuously passaging on MA104 cells. Subsequently, the pathogenicity of the isolated strain in piglets was investigated.The piglets of the PoRV-infection group were orally inoculated with 1 mL of 1.0 × 10⁶ TCID50 PoRV, whereas those of the mock-infection group were fed with an equivalent amount of DMEM. (3) Results: Fecal samples were collected from 28 piglets, all of which tested positive for RVAs. A G5P[23] genotype porcine rotavirus strain was successfully isolated from one of the positive samples and named RVA/Pig/China/JS/2023/G5P[23](JS). The genomic constellation of this strain was G5-P[23]-I5-R1-C1-M1-A8-N1-T1-E1-H1. Sequence analysis revealed that the genes VP3, VP7, NSP2, and NSP4 of the JS strain were closely related to human RVAs, whereas the remaining gene segments were closely related to porcine RVAs, indicating a reassortment between porcine and human strains. Furthermore, infection of 15-day-old piglets with the JS strain resulted in a diarrheal rate of 100% (8 of 8) and mortality rate of 37.5% (3 of 8).(4) Conclusion: The isolated G5P [23] genotype rotavirus strain, which exhibited strong pathogenicity in piglets, may have resulted from recombination between porcine and human strains. It may serve as a potential candidate strain for developing vaccines, and its immunogenicity can be tested in future studies.

Infection by the novel duck reovirus (NDRV) in ducklings causes high mortality, which leads to substantial economic losses in the duck industry in China. To date, no commercial vaccine is available for this disease. In this study, linear B cell epitopes of the σB protein of the NDRV were predicted and recombinant multiple linear B cell epitopes (MLBEs) were constructed through linkers. The recombinant MLBEs were then expressed and purified. One-day-old Muscovy ducklings were immunized with different doses of MLBEs and challenged with 5 × 10⁴ ELD₅₀ of the virulent CHY strain of NDRV 14 days after immunization. The ducklings vaccinated with 20 and 40 μg of MLBE performed no clinical signs or gross or histopathological lesions, indicating 100% protection against infection. The viral load in the liver and spleens of these birds was significantly lower than that in the control group. Additionally, these ducklings exhibited positive seroconversion at 7 days after vaccination on enzyme-linked immunosorbent assay. These results indicate that MLBE of σB could be used as a candidate for developing vaccines against NDRV infection.

Porcine rotavirus (PoRV) is widely prevalent in Chinese pig farms and causes substantial economic losses to the swine industry. Virus isolation remains technically challenging, and the pathogenicity of circulating strains in piglets is incompletely characterized. A total of 481 diarrhoeic samples were collected from Anhui province, China. PoRV was detected on 83.33% (15/18) of the farms, with a sample-level positivity rate of 28.48% (137/481). Phylogenetic analysis of the VP7 and VP4 genes identified G9 (50.00%) and P[23] (13.33%) as the predominant genotypes. A PoRV strain was successfully isolated and named RVA/Pig/China/GL/2022/G9P[23] (GL/2022), exhibiting a genomic constellation of G9–P[23]–I5–R1–C1–M1–A8–N1–T1–E1–H1. Comparative phylogenetic analyses revealed that GL/2022 shares high homology with both human and porcine RVA lineages, indicating possible interspecies reassortment. Importantly, this study represents the first systematic comparison of the evolutionary dynamics of GL/2022 with those of previously reported G9P[23] strains. Pathogenicity experiments demonstrated that GL/2022 induced severe enteric lesions and 50% mortality in neonatal piglets. These findings highlight PoRV's genetic complexity and zoonotic potential, providing critical insights for disease surveillance and vaccine development.