Hanqin Shen

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.

Porcine epidemic diarrhea virus (PEDV), an enteropathogenic coronavirus of significant veterinary importance, induces severe watery diarrhea and dehydration in swine populations, with mortality rates approaching 100% in neonatal piglets. Among PEDV variants, S-INDEL strains have drawn increasing attention because of their genetic divergence and uncertain pathogenic potential in the field. In 2024, a novel S-INDEL PEDV strain, designated PEDV CH/JSHA2024, was isolated from intestinal samples of diarrheic piglets on a commercial swine farm in Jiangsu Province, China. Recombination analysis revealed that the spike (S) glycoprotein gene of this strain originated from genetic recombination between the Ch/HNLH/2015 and SQ2014 progenitor strains. Comparative genomic analysis with the prototype OH851 strain revealed multiple amino acid substitutions and insertions, including multiple amino acid substitutions and insertions within the S1 subunit, along with the absence of a conserved N-glycosylation site at position 114 (N114). The pathogenic potential of PEDV CH/JSHA2024 was assessed in pigs of different ages and maternal antibody levels. The strain caused 100% mortality in 1-day-old piglets (6/6), 50% mortality in 3-day-old piglets lacking maternal antibodies (3/6), and no mortality in 3-day-old piglets with maternal antibodies (0/6). In older animals, including 4-week-old weaned piglets and gilts, infection led to acute diarrhea and reduced feed intake but not fatality. Notably, high levels of serum IgA antibodies persisted for at least two months postinfection. These findings advance our understanding of coronavirus evolution through genetic recombination events. The establishment of this experimental model provides a valuable platform for elucidating the molecular determinants underlying S-INDEL strain pathogenesis, with particular implications for vaccine development and herd immunity strategies.

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.

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.

(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.