Molecular epidemiological survey of group A porcine rotavirus in selected areas of China during 2022-2023

【Objective】To investigate the molecular epidemiological characteristics of group A porcine rotavirus(RVA) in some areas of China, the current dominant genotypes were identified to provide theoretical basis for RVA prevention and control as well as vaccine research and development. 【Method】From January 2022 to March 2023, 434 stool samples of diarrheal piglets were collected from 36 large-scale pig farms in provinces of Jiangsu, Jiangxi, Fujian, Shanxi and Guizhou. RVA positive status of the samples was detected by RT-PCR. VP7 and VP4 genes of some RVA positive samples were amplified and sequenced, and multiple sequences were compared with various reference sequences. The nucleotide sequence homology analysis was performed by MegAlign, and the phylogenetic evolutionary tree was constructed by the adjacency method of MEGA 7.0. 【Result】RT-PCR results showed that 196 of 434 piglet diarrhea samples were RVA positive, with an detected positive rate of 45.16%. The detected positive rates in 2022 and early 2023 were 40.37%(132/327) and 59.81%(64/107), respectively. According to the regional analysis, the RVA detected positive rate was the highest in Jiangsu(57.70%), followed by Jiangxi(55.71%), the RVA detected positive rates of Fujian, Guizhou and Shanxi were 35.66%,30.00% and 22.33%. The VP4 and VP7 gene sequences of 12 strains of RVA from different areas were obtained. The results of genetic evolution analysis showed that G9 was the dominant genotype(83.4%), G4 and G5 accounted for 8.3% respectively. In P type, P7 was the dominant genotype(75.0%), followed by P13 and P23, accounting for 16.7% and 8.3% respectively. The 12 RVA strains were classified into four genotypic combinations, namely G9P7(75%), G5P13(8.3%), G9P13(8.3%) and G4P23(8.3%). 【Conclusion】The detected positive rate of RVA in pig farms in some provinces of China continues to increase, and the RVA genotypes in pig herds are complex and diverse, and the dominant combination genotype is G9P7. Therefore, it is necessary to continuously monitor the prevalence of RVA in pigs, develop preventive measures combined with genotypic pathogenicity, and develop targeted vaccines in the future.