Sequence analysis of VP7 and VP4 genes of G1P[8] rotaviruses circulating among diarrhoeic children in Pune, India: A comparison with Rotarix and RotaTeq vaccine strains

摘要

Background: The G1P[8] rotaviruses are a common cause of rotavirus diarrhoea among children in India. Two rotavirus vaccines licensed in India, Rotarix and RotaTeq, contain strains with G1 and P[8] genotypes. A comparative analysis of these genotypes in the live rotavirus vaccines with circulating rotavirus strains is essential for assessment of rotavirus diversity. Methods: GIP[8] strains detected during rotavirus surveillance among diarrhoeic children hospitalized in Pune in 1992-1993 and 2006-2008, were included in the study. Amplification, sequencing and phylogenetic analysis of the VP7 and VP4 genes were carried out for identification of the G1 and P[8] lineages, respectively. Antigenic epitopes of VP7 and VP4 encoded proteins were compared to determine the differences between the GIP[8] strains from Pune and the vaccine strains. Results: G1-Lineage 1,P[8]-Lineage 3 strains were predominant in Pune during 1992-1993 and 2006-2008. Strains of G1-Lineage 2, P[8]-Lineage 3 and G1-Lineage 1, P[8]-Lineage 4 were detected at low levels during 2006-2008. The G1-Lineage 1, P[8]-Lineage 3 strains showed up to eight amino acid changes, each in the VP7 and VP4 epitopes, with respect to the Rotarix vaccine strain (G1-Lineage 2, P[8]-Lineage 1) and the G1 (Lineage-3) and P[8] (Lineage 2) components of the RotaTeq vaccine. The G1 -Lineage 2 strains were closer to both vaccine strains with no or only two amino acid substitutions in the VP7 epitopes. The divergent p[18]-Lineage 4 (PP354-like) strains showed fourteen and fifteen amino acid differences, with Rotarix and RotaTeq vaccine strains, respectively, in the VP4 epitopes. Conclusion: The differences between the G1 P[8] strains in Pune and the G1 and P[8] components of the vaccine strains need to be described for appropriate evaluation of vaccine shedding. Continuous monitoring of the GIP[8] subgenotypic lineages would be necessary to study any long term impact of vaccine use on GIP[8] strain evolution