Molecular Epidemiological Study Of Norovirus In Acute Gastroenteritis

Background Norovirus (NoV) is the genus Norovirus in the family Caliciviridae. According to the area of RdRp or VP1, NoV can be grouped into five genogroups including GⅠ-GⅤ, of which GⅠ and GⅡ are prevalent, and GⅡ.4genotype is the most prevalent in acute gastroenteritis patients. Researches begin to pay more attention to NoV recombination. Objective The study collected diarrhea specimens from301hospital, detected the positive rate and determined the genotypes, and discussed the molecular epidemiology of NoV gastroenteritis. Method Because NoV can not be cultivated and there is no appropriate model, the method of RT-PCR was used to determine the molecular epidemiology of NoV. Result Out of685samples,66positive specimens were detected out and the prevalence was9.6%(66/685), of which36was male,30female, and the prevalence was9.9%(36/365) and9.4%(30/320) respectively. There was no significant difference in distribution. The prevalence was no difference between different age groups and the result was same between inpatient and outpatient. NoV gastroenteritis had no seasonal distribution.43specimens of66was classified, and the number belongs to G I was10accounting for22.7%, including2G Ⅰ.3,1GⅠ.4,4G Ⅰ.5and3G Ⅰ.7. GⅡgenogroup included33accounting for77.3%, of which GⅡ.4accounted for60.6%(20/33) following7GⅡ12,2GⅡ.6,1GⅡ.2,1Ⅱ.3,1GII.5.There were6specimens mixed with G I and GII and3specimens were classified as G Ⅰ.3/GⅡ.7, G Ⅰ.5/GⅡ.5、G Ⅰ.4/GⅡ.4. According to the RdRp classification, there was recombination between NoV, GⅡ.g/GⅡ.12and GⅡ12/GⅡ.3were found in the study and the breakout point located in the upstream of ORF1/ORF2overlap. Retrieving NoV database, recombination was prevalent which included Ⅰ.a/Ⅰ.3、 Ⅰ.d/Ⅰ.3、Ⅰ.b/Ⅰ.6、Ⅰ.d/Ⅰ.3, Ⅱ.n/Ⅱ.22、Ⅱ.12/Ⅱ.3、Ⅱ.7/Ⅱ.14、Ⅱ.g/Ⅱ.12. Ⅱ.g/Ⅱ.3. Conclude The prevalence was9.6%. There was no difference between sex, age, inpatients and outpatients and there was no seasonal variation. The main symptoms were abdominal pain, nausea, vomit and fever. There were many genotypes in our study and the main genotypes were GⅡ.42006a and2006b. GⅡ.g ORF1and GⅡ.12ORF2could combine together, GⅡ.12ORF1and GⅡ.3ORF2combined also and these kinds of recombination have been prevalent in world. From the Norovirus database we foud that there were many kinds of genotypes and the main genotypes was GⅡ.42006b. There were many kinds of recombination occoured in Norovirus G Ⅰ and GⅡ and these recombinations were all detected in the world and the influence of recombination in Norovirus GⅡ was larger than G Ⅰ.