[Analysis on molecular characteristic of VP7 and NSP4]

To explore the molecular characteristics and molecular variation of human rotavirus (HRV) strains and to understand the relationship between clinical characteristics and epidemiology of different HRV-VP7 and NSP4.

Double-strand RNA of rotavirus extracted from stool samples was used as the template for reverse transcription of gene VP7, which was followed by nested PCR for VP7 typing. NSP4 genes from 22 epidemic strains of human rotavirus isolated in Kunming in 2002 and 2003 were amplified with RT-PCR. Then cDNAs were sequenced and compared with 4 human rotavirus NSP4 (Wa, KUN, AU-1, Hochi)) and 3 animal rotavirus NSP4 (EW, OSU, SA11) available in the GenBank while the epidemic strains of human rotavirus isolated in different areas of China were compared, using the Clustal-mp, DNAssist, MEGA2 software. The G serotype of VP7 was analysed by PCR.

Serotype G1 was prevalent in 2002 while serotype G3 was the prevalent in Kumming in 2003. The NSP4 genes from 22 epidemic strains of human rotavirus isolated in Kunming in 2002 and 2003 belonged to Wa with highly conservative amino acid. Samples isolated in the same years but not in the same area shared higher homology. Symptoms associated with heavy diarrhea did not seem to be associated with NSP4 molecular variation (P > 0.05).

Obvious variations of VP7 typing were seen in the same season, as well as in different areas and years. Due to the stable nature of NSP4, it seem to be a better candidate for vaccine production, than VP7.