Molecular characterization of unusual bovine rotavirus A strains having high genetic relatedness with human rotavirus: evidence for zooanthroponotic transmission.

We report here the genomic characterization of two rare rotavirus A (RVAs) G1P[11] and G9P[X] strains detected in cattle calves from two different geographical locations in India during routine rotavirus surveillance. These strains possessed unusual G types (VP7 gene) on a bovine/artiodactyl genotype constellation, G1-P[11]-I2-Rx-Cx-Mx-Ax-N2-T6-E2-H3 (HR-B91) and G9-P[X]-I2-Rx-Cx-Mx-Ax-N2-T6-E2-H3 (WB-H2). This is the first report on molecular characterization of G9 in cattle, and second report on G1 in cattle. The VP7 gene of HR-B91 occupied lineage IIc within G1 while that of WB-H2 occupied IIIb within G9 genotype. The latter was found to be very diverse from other RVA strains of G9 genotype, and this may emerge as a new genotype in due course. The study provides evidence of zooanthroponotic transmission of human G1 and G9 RVA genes to calves. Of note, the G9 genotype was found to serve as the ancestral genotype for G1. Phylogenetic analysis of remaining gene segments revealed close relatedness to artiodactyl or artiodactyl-like human RVA strains. The findings of this study highlight the potential role of interspecies transmission and reassortment events in generating the rare rotavirus strains.