Molecular Epidemiology of Norovirus Variants Detected in Children under Five Years of Age in Hyderabad, India

Purpose: Noroviruses are common viral agents in acute diarrhea in all age groups worldwide. Norovirus has been classified into 10 genogroups, GI to GX with over 48 genotypes among them the GII.4 genotype has evolved over time with a clear pattern of periodic variant replacement. Immunity is strain or genotype specific with little or no protection conferred across genogroups. The present study was aimed to determine the epidemiology, prevalent genotypes of norovirus in children below five years of age in the Hyderabad region, India. Methods: The stool samples and clinical data were collected from 458 children below 5 years of age comprising of cases with acute gastroenteritis (n = 366) and a control group (n = 92) admitted to the pediatric ward. All the samples were tested for Norovirus by ELISA and RT-PCR. Sequencing was done for predominant strains. Results: 10.3% (n = 38) of cases and 3.2% (n = 3) of the control group were found to be Norovirus positive. Predominant genotypes were GII-82.5% followed by GI-12.5%. Conclusion Sequencing and Phylogenetic analyses of 20 GII.4 strains was done. All of the isolates are clustered away from published the GII.4 variants thus suggesting the appearance of a new variant.