Genomic characterization of nontypeable rotaviruses and detection of a rare G8 strain in Delhi, India.

Abstract

In this investigation we molecularly characterized nontypeable rotavirus strains previously identified during surveillance in New Delhi, India. The majority of strains were demonstrated to belong to genotypes G1 (54.5%) or P[8] (77.8%) based on nucleotide sequencing of fragments from their VP7 and VP4 genes. Other genotypes detected included G2, G8, G9, G12 and P[4]. A G8P[6] strain, DS108, was detected for the first time in Northern India. The VP7 gene of DS108 was most homologous with a bovine G8 strain, A5 (98.9%), indicating its bovine parentage. In contrast, the VP4 had high nucleotide homology (92.9%-99.1%) with human P[6] strains. The VP6 gene and nonstructural genes (NSP1-3 and 5) were most homologous with human rotaviruses belonging to DS1 genogroup. Interestingly, the NSP4 gene of DS108 clustered within genotype E6 that until now had only 2 representative strains, both with G12P[6] specificity (RV176-00 and N26-02). Together, these results indicate that the G8 strain, DS108, belongs to the DS1 genogroup and could be result of a human G2P[4] strain acquiring VP7, VP4 and NSP4 genes from more than one donor, similar to the evolution of G12P[6] strain RV176-00. The present study highlights the importance of characterizing multiple genes of nontypeable rotavirus strains to detect novel strains and get a more complete picture of rotavirus evolution.