VP7 Gene of human rotavirus A genotype G5: Phylogenetic analysis reveals the existence of three different lineages worldwide.

Group A rotavirus (RV-A) genotype G5, which is common in pigs, was also detected in children with severe diarrhea in Brazil, Argentina, Paraguay, Cameroon, China, Thailand, and Vietnam. To evaluate the evolutionary relationship among RV-A G5 strains, the VP7 and VP4 genes of 28 Brazilian RV-A G5 human strains, sampled between 1986 and 2005, were sequenced and compared with other RV-A G5 strains currently circulating worldwide in animals and humans. The phylogenetic analysis of RV-A G5 VP7 gene strains demonstrates the existence of three main lineages: (a) Lineage I: Brazilian strains grouped with three porcine strains from Thailand; (b) Lineage II: porcine, bovine, and equine strains from different regions; (c) Lineage III: human strains isolated in Asia and Africa, and two porcine strains from Argentina. The VP8* (*non-typable) subunit of VP4 gene sequencing showed that all P[8] strains fell into three major genetic lineages: P[8]-1; P[8]-2; and P[8]-3. These results showed that the RV-A G5 strains circulating in humans are the result of two independent zoonotic transmission events, most likely from pigs.