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Deduced amino acid sequence and phylogenetic analyses of a group A rotavirus G9P[6] strain (designated as mcs/13-07), detected from a 3-year-old child in Eastern India, revealed a VP8* closely related to porcine P[6] strains (P[6] sublineage 1D), and the VP7 clustered with G9 lineage-III strains. To our knowledge, this is the first report of human P[6] strain clustering in sublineage Id. Thus, to further characterize the evolutionary diversity of strain mcs/13-07, all gene segments were analyzed. VP6 and NSP4 exhibited genetic relatedness to Wa-like human subgroup II strains, while VP1-3, NSP1-3 and NSP5 were closely related to porcine strains. Based on the new classification system of rotaviruses, mcs/13-07 revealed a G9-P[6]-I1-R1-C1-M1-A8-N1-T1-E1-H1 genotype with close similarity to human Wa-like and porcine Gottfried strains. Therefore, considering the porcine-like or porcine origin of multiple gene segments, it might be tempting to assume that strain mcs/13-07 represents a rare instance of whole-virus transmission from pig to human, after which the virus evolved with time. Alternatively, it is possible that strain mcs/13-07 resulted from multiple reassortment events involving human subgroup II and porcine P[6] strains. Nevertheless, detection of strain mcs/13-07 provides further evidence for complex interspecies transmission events, which are frequent in developing countries.

To clarify the phylogenetic relatedness of rotaviruses causing gastroenteritis in children and adults, an epidemiologic investigation was conducted in Mymensingh, Bangladesh, during the period between July 2004 and June 2006. A total of 2,540 stool specimens from diarrheal patients from three hospitals were analyzed. Overall, rotavirus-positive rates in children and adults were 26.4 and 10.1%, respectively. Among the 155 rotavirus specimens examined genetically from both children and adults, the most frequent G genotype was G2 (detection rate: 54.0 and 47.6%, respectively), followed by G1 (21.2 and 26.2%, respectively), and G9 (15.9 and 9.5%, respectively). G12 was also detected in five specimens (3.2% in total; four children and one adult). Sequence identities of VP7 genes of G2 rotaviruses from children and adults were higher than 97.8%, while these Bangladeshi G2 viruses showed generally lower identities to G2 rotaviruses reported elsewhere in the world, except for some strains reported in African countries. Similarly, extremely high sequence identities between children and adults were observed for VP7 genes of G1, G9 and G12 rotaviruses, and also for the VP4 genes of P[4], P[6], and P[8] viruses. Rotaviruses from children and adults detected in this study were included in a single cluster in phylogenetic dendrograms of VP7 or VP4 genes of individual G/P types. Rotaviruses with two emerging types, G9 and G12, had VP7 genes that were phylogenetically close to those of individual G-types recently reported in Bangladesh and India and were included in the globally spreading lineages of these G-types. These findings suggested that genetically identical rotaviruses, including those with the emerging types G9 and G12, were circulating among children and adults in city and rural areas of Bangladesh.