Genotypes Of Rotaviruses From Infants With Diarrhea In Kunming City From October To December In 2007 And 2008

Objective To investigate molecular epidemic features of rotavirus in infants with diarrhea in Kunming, China from 2007 to 2008.Methods Stool specimens were collected from 96 children (46 of 2007 and 50 of 2008) who were hospitalized in the Department of Peadiatrics, the First Affiliated Hospital of Kunming Medical College from October to December in 2007 and 2008.Colloidal Gold method were used to detect rotavirus double stranded RNA (dsRNA) from stool specimens and cDNA fragments of the genes encoding VP7 and VP4 were amplified from the rotavirus RNA positive specimens by using Reverse transcription polymerase chain reaction (RT-PCR). Genotypes of VP7 and VP4 from the rotavirus positive specimens were determined by nest polymerase chain reaction (net-PCR). NSP4 gene from 12 (6 of 2007 and 6 of 2008) of the positive VP7 samples was amplified by RT-PCR. Then cDNAs were sequenced and analyzed by DNAassist,Clustal-mp and MEGA 4.0 software.Results (1)Rotavirus dsRNA was detected from 29(63%) of 46 stool specimens in 2007 and 31(62%) of 50 stool specimens in 2008. (2)RT-PCR were performed for 29 stool specimens and VP7 and VP4 gene products were obtained from 26 samples in 2007 . The most dominant G type of rotavirus in this group was G1 (42.3%) and P type was P[8] (61.5%). G2 (34.6%) and P[4](48.5%) were the next important ones in this group. RT-PCR were performed for 31 stool specimens and VP7 and VP4 gene products were obtained from 29 samples in 2008 . The most dominant G type of rotavirus in this group was G1 (41.4%) and P type was P[8] (86.2%). G3 (34.5%) and P[4](13.8%) were the next important ones in this group. G1P[8] was the most mixed types in 2007 and 2008.(3)NSP4 gene was amplifie from 12(6 of 2007 and 6 of 2008) VP7 positive samples. Among the twelve Kunming strains,ten were Wa strains and two were KUN strains. The nucleotide homologies of the ten Wa strains to the four HRV standard strains (Wa, KUN, AU-1, Hochi) and three animal RV( EW,OSU,SAll)were 96.3%,85.3%,84.7%,95.1% and 57.7%, 92% , 82.8%. Compared with the epidemic strains in other different areas of China, the nucleotide homology of the NSP4 gene were over 95%.Compared with the standard strains from the above GenBank Database ,the nucleotide homology of the two KUN strain were 85.3%, 98.2%, 82.8%, 85.9% and 60.1%, 85.3% , 94.3%. And compared with the epidemic strains in other different areas of China, the nucleotide homology of the NSP4 gene were aboat 85%.Conclusion Rotavirus is one of the most important pathogens for diarrhea in infants in Kunming City from October to December in 2007 and 2008.The most dominant genotype of rotaviruses circulating in Kunming was G1P[8]. Among the NSP4 of the twelve Kunming strains, ten were Wa strains and two were KUN strains. The most dominant genotype of NSP4 was Wa strain.