Increase in prevalence of human group A rotavirus G9 strains as an important VP7 genotype among children in eastern India.

Background: In addition to four globally important group A rotavirus (GARV) VP7 genotypes (G1-G4), recent surveillance studies have revealed importance of G9 strains as an aetiological agent of infantile diarrhoea.
Objective: Detection and genotyping of GARVs from children, admitted with gastroenteritis to Dr. B.C. Roy Memorial Hospital for Children, Kolkata, India.
Study Design: GARVs were detected in stool specimens by RNA electrophoresis in polyacrylamide gels. G- and P-genotyping were performed by seminested multiplex PCR assays. VP7 gene of rotavirus G9 and G12 strains were sequenced for further analysis.
Results: Of 249 GARV strains (n=668, May 2005-December 2006), G- and P-genotyping were successfully accomplished for 197 and 204 samples, respectively. G1 (41.6%) was most prevalent G-genotype followed by G2 (33%), G12 (14.2%), G9 (10.1%) and mixed genotype (1%). Prevalent P-genotypes were P[8] (54.4%), P[4] (31.4%), P[6] (7.3%) and mixed genotype (6.9%). Overall, G1P[8], G2P[4], G9P[8], G12P[8] and G12P[6] were identified as important G-P combinations. Phylogenetic analysis of 13 G9 strains revealed clustering within G9 lineage III. Nine of 28 G12 strains were sequenced and exhibited phylogenetic clustering with previously reported G12 strains from Kolkata.
Conclusion: In comparison to our previous data (2003 to April 2005), G9 and G2P[4] strains established themselves in a short time span as important genotypes in eastern India.