Genotyping Study of Novovirus Infection in Clinic Children Under 5 years in Guangzhou

Objective To study the infection condition and genotype of norovirus in sporadic diarrhea cases under 5 years old in surveillance hospitals in Guangzhou.Method Stool specimens and clinical data were collected from 954 outpatients with clinical diagnosed virus diarrhea in surveillance hospitals from 2007 to 2008.Rotavirus and norovirus were detected by ELISA method.Norovirus was detected from the specimens positive to norovirus ELISA by reverse transcription polymerase chain reaction (RT-PCR) and the PCR products were purified and sequenced.The sequences were analyzed by comparing to GenBank to identify genotype.Results All of the 954 specimens,rotavirus account for 30.8%,norovirus account for 18.8%.The incidence peak of norovirus infection was in 9-11 months and cases less than 2 years old accounted for 91.6% of total cases,which concentrated in the 6-23 months.The positive rate of norovirus nucleic acid was 80.4% (144/179) by RT-PCR.The 144 norovirus nucleic acid positive specimens were identified belong to the same genotype (GⅡ4) except for one belong to GⅡ2 by comparing to GenBank.Conclusions Norovirus is one of the major pathogen contributing to the virus diarrhea only second to rotavirus in children under 5 years old in Guangzhou.Children under 2 years old are at higher risk of infection.Genotype(GⅡ4) was the predominant strain from 2007 to 2008 in Guangzhou.