Genetic and Antigenic Variability in VP4 and VP7 of Group A Human Rotavirus in Yunnan, China from 2015-2020.

Background: Rotavirus(RVs) A is one of major reasons which causes severe dehydration diarrhea. It is also one of the high morbidity disease in children. There are only a few reports about the changes in prevalence and VP4 / VP7 genotype of RVs in southwest China.Here is the report about the prevalence of RV from 2015 to 2020 in Yunnan, southwest China. Methods: The virus genes were extracted from RV positive samples, then VP4/VP7 genes were amplified, followed by sequencing and Gene typing, Phylogenetic analysis, antigenic epitope variation analysis and selective pressure analysis were also performed. Results: 135 VP4 gene sequences and 143 VP7 gene sequences were obtained from stool samples during 2015 to 2020. Of them, P[8] genotype accounted for 97.0% of total, while the P[4] genotype accounted for 3.0%. As for the VP7 genotype, G9 genotype accounted for 86.0% of total, the G3 genotype accounted for 9.1%, and the G2 genotype accounted for 4.9%. G9P[8] was identified as the predominant RV strain during the epidemic season in Yunnan during 2015 to 2020. Phylogenetic analysis showed that G9 genotype sequences were primarily similar to African strains (KJ753473, KY661937), while P[8] genotype sequences were close to Southeast Asian strains (JQ837878, KX362594). In antigenic epitope variation analysis, among 37 epitope of P[8] genotype, the RotaTeq™ vaccine strain covers 31 amino acid positions, Rotarix™ covers 28 amino acid positions, while LLR covers only 9. In the representative sequence of the G9 genotype, RotaTeq™ vaccine strains cover 27 out of 29 amino acid positions, Rotarix™ cover 16 positions, and LLR cover 16 positions. The results of the selective pressure analysis indicated potential positive sites for the G9P[8] genotype located at vp7-44, vp7-100, vp7-221, vp7-278, vp4-3 and vp4-4. Conclusions: Our study shows that G9P [8] is the most dominant rotavirus genotype in Yunnan China. Consistent with the recent epidemic trend of RV strains in China, this study could provide new perspectives on vaccine research.