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Porcine rotavirus A (PoRVA) is an enteric pathogen capable of causing severe diarrhea in suckling piglets. Investigating the prevalence and molecular characteristics of PoRVA in the world, including China, is of significance for disease prevention. In 2022, a total of 25,768 samples were collected from 230 farms across China, undergoing porcine RVA positivity testing. The results showed that 86.52% of the pig farms tested positive for porcine RVA, with an overall positive rate of 51.15%. Through the genetic evolution analysis of VP7, VP4 and VP6 genes, it was revealed that G9 is the predominant genotype within the VP7 segment, constituting 56.55%. VP4 genotypes were identified as P[13] (42.22%), P[23] (25.56%) and P[7] (22.22%). VP6 exhibited only two genotypes, namely I5 (88.81%) and I1 (11.19%). The prevailing genotype combination for RVA was determined as G9P[23]I5. Additionally, some RVA strains demonstrated significant homology between VP7, VP4 and VP6 genes and human RV strains, indicating the potential for human RV infection in pigs. Based on complete genome sequencing analysis, a special PoRVA strain, CHN/SD/LYXH2/2022/G4P[6]I1, had high homology with human RV strains, revealing genetic reassortment between human and porcine RV strains in vivo. Our data indicate the high prevalence, major genotypes, and cross-species transmission of porcine RVA in China. Therefore, the continuous monitoring of porcine RVA prevalence is essential, providing valuable insights for virus prevention and control, and supporting the development of candidate vaccines against porcine RVA.

Rotavirus A species (RVA), RVB, RVC, and RVH are four species of rotaviruses (RVs) that are prevalent in pig herds, and co-infections occur frequently. In this study, a quadruplex real-time quantitative RT-PCR (RT-qPCR) for the simultaneous detection of four porcine RVs was developed by designing specific primers and probes based on the VP6 gene of RVA, RVB, RVC, and RVH, respectively. The method showed high specificity and could only detect RVA, RVB, RVC, and RVH, without cross-reaction with other porcine viruses; showed excellent sensitivity, with a limit of detection (LOD) of 1.5 copies/µL for each virus; showed good repeatability, with intra-assay coefficients of variation (CVs) of 0.15–1.14% and inter-assay CVs of 0.07–0.96%. A total of 1447 clinical fecal samples from Guangxi province in China were tested using the developed quadruplex RT-qPCR. The results showed that RVA (42.71%, 618/1447), RVB (26.95%, 390/1447), RVC (42.92%, 621/1447), and RVH (13.68%, 198/1447) were simultaneously circulating in the pig herds, and the co-infection rate of different species of rotaviruses was found to be up to 44.01% (579/1447). The clinical samples were also detected using one previously reported method, and the coincidence rate of the detection results using two methods was more than 99.65%. The phylogenetic tree based on the VP6 gene sequences of RVH revealed that the porcine RVH strains from Guangxi province belonged to the genotype I5, which was closely related to Japanese and Vietnamese strains. In summary, an efficient, sensitive, and accurate method for the detection and differentiation of RVA, RVB, RVC, and RVH was developed and applied to investigate the prevalence of porcine RVs in Guangxi province, China. This study is the first to report the prevalence of porcine RVH in China.

Porcine viral diarrhea diseases affect the swine industry, resulting in significant economic losses. Porcine epidemic diarrhea virus (PEDV) genotypes G1 and G2, and groups A and C of the porcine rotavirus, are major etiological agents of severe gastroenteritis and profuse diarrhea, particularly among piglets, with mortality rates of up to 100%. Based on the high prevalence rate and frequent co-infection of PEDV, RVA, and RVC, close monitoring is necessary to avoid greater economic losses. We have developed a multiplex TaqMan probe-based real-time PCR for the rapid simultaneous detection and differentiation of PEDV subtypes G1 and G2, RVA, and RVC. This test is highly sensitive, as the detection limits were 20 and 100 copies/μL for the G1 and G2 subtypes of PEDV, respectively, and 50 copies/μL for RVA and RVC, respectively. Eighty-eight swine clinical samples were used to evaluate this new test. The results were 100% in concordance with the standard methods. Since reassortment between porcine and human rotaviruses has been reported, this multiplex test not only provides a basis for the management of swine diarrheal viruses, but also has the potential to impact public health as well.