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Full genomic analyses of human rotavirus strains possessing the rare Pb VP4 subtype
- Ghosh, Souvik, Paul, Shyamal Kumar, Yamamoto, Dai, Nagashima, Shigeo, Kobayashi, Nobumichi
- Infection, genetics, and evolution 2011 v.11 no.6 pp. 1481-1486
- Rotavirus B, diarrhea, genes, genetic relationships, genomics, genotype, humans, nucleotide sequences, phylogeny, public health, vaccines, Bangladesh
- Rotaviruses with the P VP4 genotype are a major cause of acute infantile diarrhea. The P genotype is classified into two genetically distinct subtypes, Pa and Pb. Most of the P strains belong to subtype Pa, whilst Pb strains are rare. To date, the whole genomes of a few Pa strains have been analyzed, whilst there are no reports on full genomic analysis of the Pb strains. To determine the genetic makeup of the rare Pb strains and their overall genetic relatedness to the Pa strains, the present study analyzed the full genomes of a human G9Pb strain, MMC38, and a G1Pb strain, MMC71, detected in Bangladesh in 2005. By nucleotide sequence identities and phylogenetic analyses, strains MMC38 and MMC71 exhibited a human rotavirus Wa-like genotype constellation. Except for the VP4 gene, all the genes of strains MMC38 and MMC71 were closely related to cognate genes of the contemporary and more recent human Wa-like G1Pa, G9Pa, G11Pa, G11P, G12P and G12Pa strains, including those from Bangladesh. Therefore, strains MMC38 and MMC71 possessed the genetically distinct Pb VP4 gene on a common human Wa-like genetic backbone, pointing towards their possible origin from reassortment events between common human Wa-like strains and unidentified rotavirus strains possessing the rare Pb-like VP4 gene. Since strains with this stable Wa-like genetic backbone can spread rapidly, and it is not certain as to whether the current rotavirus vaccines will be equally efficacious against the Pb strains as the Pa strains, proper detection of Pb strains and their whole genomic analyses might be of public health significance. To our knowledge, the present study is the first report on full genomic analysis of the rare Pb rotavirus strains.