Genetic characterization of a novel, naturally occurring recombinant human G6P[6] rotavirus.

A binary classification system has been established for group A rotaviruses, with the viral capsid protein VP7 defining G types and VP4 defining P types. At least 15 G types and 21 P types have been isolated globally with various G and P combinations. Most of the currently circulating human rotaviruses belong to G1P[8], G2P[4], G3P[8], and G4P[8]. We report a human rotavirus strain (B1711) with a novel genotypic VP7/VP4 combination of G6P[6]. This unique rotavirus was isolated from a 13-month-old human immunodeficiency virus (HIV)- negative child of an HIV-seropositive Malian mother that was hospitalized with severe diarrhea in Belgium after returning from a trip to Mali. The VP7 and VP4 genes of the rotavirus strain were sequenced, and phylogenetic trees were constructed. Nucleotide and amino acid sequence comparisons with 15 known G genotypes indicated that the VP7 sequence of strain B1711 was most closely related to an American (Se584) and an Italian (PA151) human G6 strain (95 to 96% nucleotide and 98% amino acid identity). Comparison of the VP4 sequence with 21 P types showed the closest similarity to P[6] genotypes, with greatest similarity to a G8P[6] Malawi strain (mw131) (97% nucleotide and 98% amino acid identity). The B1711 strain is the first reported rotavirus isolate with a G6P[6] genotypic combination. The discovery and surveillance of novel human and nonhuman rotavirus G or P types or of novel G/P combinations is essential for the design of future rotavirus vaccines and for our understanding of rotavirus diversity and evolution.