Changing pattern of human group A rotaviruses: Emergence of G12 as an important pathogen among children in eastern India

Background: Rotavirus genotypes, G1-G4 and G9 are associated with childhood diarrhoea throughout the world. In our previous study, we detected G1 G2, G4 and three G12 strains from Kolkata, India. Objectives: To study the prevalence of G- and P-genotypes of rotaviruses associated with dehydrating diarrhoea in children admitted to two leading hospitals in eastern India. Study design: An active surveillance was conducted for elucidation of rotavirus infection in two leading hospitals in Kolkata, West Bengal and Berhampur (GM), Orissa, India, separated by 603 km from January 2003 to April 2005. The rotaviruses were detected by RNA electrophoresis in polyacrylamide gels. G- and P-typing of the positive samples were accomplished by amplifying VP7 and VP4 genes by RT-PCR and genotyped by seminested multiplex PCR methods. Sequencing, sequence analysis and phylogenetic analysis of VP7 genes of G12 strains were carried out to understand the variations between the strains isolated from different parts of the world. Results: The genotypic distribution varied remarkably from our earlier study period (1998-2001) with G1 (53.8%) being the most predominant strain followed by G2 (22.5%), G12 (17.1%), G9 (2.1%) and not a single G3 or G4 isolate was detected separately. 35.2% samples exhibited mixed P-types followed by P[4] (31.7%), P[8] (21.8%) and P[6] (9.8%). The phylogenetic analysis of G12 strains revealed that the G 12 strains detected from different parts of the world clustered into three different lineages. Though VP7 sequences of G12 strains isolated from Kolkata and Berharnpur are conserved, their P-types were different. Conclusion: During this study period we reported emergence of G12 strains as an important pathogen among children in eastern India, thus necessitating its inclusion in future polyvalent vaccine to control rotavirus diarrhoea. (c) 2006 Elsevier B.V. All rights reserved.