Nucleotide sequence of the VP7 gene of human rotavirus isolated in Calcutta, India: possible emergence of a new subtype of serotype I.

We have investigated the serotype-specific glycoprotein gene (VP7) of a short electropherotype and subgroup I rotavirus (ID 45/2) recovered from a child suffering from acute diarrhea. The nucleotide sequence of the human (ID 45/2) rotavirus genome segment 8/9, which encodes the serotype-specific glycoprotein (VP7) has been determined. Comparison of the nucleotide sequence of ID 45/2 to the sequences of other rotaviruses belonging to different serotypes (G1-14) revealed only 67-78% identity. Comparison of the deduced amino acid sequence of ID 45/2 VP7 protein to the sequences of other VP7 proteins showed that the majority of the amino acid differences are clustered at the N-terminus (residues 1-49), with a positional shift of the initiation codons as well as possession of one stretch of hydrophobic signal peptide instead of two. On the basis of other rotaviral characteristics, such as the conserved cysteine and proline residues together with the potential glycosylation site, it is proposed that this local strain (ID 45/2) might represent a new subtype related to serotype G1. Dot blot hybridization using ID 45/2 cDNA as probe indicated the prevalence of this strain in Eastern India.