Molecular characterization of unusual human G5P[6] rotaviruses identified in China.

BACKGROUND: We found an unusual human rotavirus, LL36755 of G5P6] genotype, in a stool sample collected in Lulong County, Hebei Province, China. This is the first detection of rotavirus serotype G5 in Asia. OBJECTIVES: To identify and characterize G5 rotaviruses in 988 stool samples collected from children under 5 years old with acute gastroenteritis. STUDY DESIGN: We analyzed 459 rotavirus-positive samples with RT-PCR using G5 genotype-specific primers. The G5 strains were sequenced. RESULTS: Two additional G5-positive samples (LL3354 and LL4260) were identified. VP7, VP4, VP6 and NSP4 genes of LL3354, LL4260 and LL36755 strains were sequenced. The VP4 sequences formed a group with porcine P6] strains. The VP6 sequences of strains LL3354 and LL36755 were phylogenetically close to the major clusters of SGI and SGII rotaviruses, respectively. The deduced VP6 protein of strain LL4260 had characteristics of both SGI and SGII strains, but best fit with a cluster of atypical SGI viruses. In addition, based on NSP4 sequences, the three G5 strains belonged to genogroup B and were closest to human strain Wa. CONCLUSION: These results indicate a dynamic interaction of human and porcine rotaviruses and suggest that reassortment could result in the stable introduction and successful spread of porcine gene alleles into human rotaviruses.