| Objective:To analyze the molecular epidemiological characteristics of Norovirus(No V)infection in hospitalized children in Tianjin Children’s Hospital in 2018.Methods:Single center study.From January to December 2018,a total of 2185 stool specimens were collected from the children with acute gastroenteritis possibly caused by virus infection in Tianjin Children’s Hospital.Norovirus was detected by real-time fluorescence reverse transcription polymerase chain reaction(RT-PCR).The capsid protein VP1(VP1)region of positive samples was amplified and sequenced.The phylogenetic tree was constructed by using MEGA5.05 for analyzing the results.The detection of No V in different age groups and different months were compared by using SPSS 20.0.Results:Among the 2185 stoolspecimens,610 were No V positive,the positive rate was 27.9%(610/2185).All of the positive samples were GⅡgenogroup.Seven genotypes were found,which are GⅡ.1、GⅡ.2、GⅡ.3、GⅡ.4、GⅡ.6、GⅡ.13 and GⅡ.17 genotypes,with GⅡ.3 genotype accounting for 46.2%(151/327),GⅡ.4genotype accounting for 40.1%(131/327),GⅡ.2 genotype accounting for4.6%(15/327),other genotypes accounting for 9.1%(30/327).There was a significant difference in No V detection rate among different age groups(χ~2=17.050,P=0.002).Among the positive specimens,the detection rate of less than or equal to 3 years old was the highest which is accounting for 89.2%.And children under 1 year old are more likely to show clinical symptoms.Also there was a significant difference in No V detection rate among different months(χ~2=225.153,P<0.001).The epidemic season is in winter and spring,and GⅡ.4 is the main type from November to December,and GⅡ.3 is the main type from January to March.There was no significant difference in the detection rate of Nov between different gender groups(?~2=0.991,P=0.330).Among the clinical symptoms of Nov infection in children,diarrhea accounted for 79.7%(392/492),vomiting 51.8%(255/492),fever 75.0%(369/492),and respiratory symptoms 42.3%(208/492).There was significant difference between GⅡ.3 and GⅡ.4 No V infection in children with granulocytopenia(χ~2=11.270,P=0.001),and also in children with respiratory symptoms(χ~2=7.257,P=0.007).GⅡ.3 is more likely to be associated with granulocytopenia than GⅡ.4.But GⅡ.4 is more likely to be associated with respiratory symptoms than GⅡ.3.In addition,the difference between the two genotypes was statistically significant(χ~2=10.314,P=0.001),which showed that GⅡ.4 was more likely to be infected with rotavirus than GⅡ.3.No significant specificity was found in leukocyte count,C-reactive protein,PCT and myocardial enzyme CK-MB,which can only be used as an auxiliary laboratory reference for Nov infection.It was found that the gene sequences of 21 representative strains were highly homologous and clustered.In addition,we found that norovirus GⅡ.3 and GⅡ.4 had high homology with GⅡ.P16-GⅡ.3 in Novosibirsk,Russia,and GⅡ.Pe-GⅡ.4 in Taizhou in 2017.It is suggested that there may be a variety of recombinant strains of Nov infection in children in 2018,which needs to be analyzed in further study.Conclusions:GⅡ.3 and GⅡ.4 were the main genotypes of No V infection in children in Tianjin in 2018.Children aged 3 and under are susceptible to Nov.There was no significant gender difference in Nov infection,which was more prevalent in winter and spring.The main clinical symptoms of children infected with Nov are diarrhea,vomiting,fever,dehydration,abdominal pain,respiratory symptoms and granulocytopenia,and also it can be combined with rotavirus and adenovirus infection.Leukocyte count,C-reactive protein,PCT and myocardial enzyme CK-MB had no significant specificity in Nov infection.The Multiple genotypes suggests that the monitoring and prevention of No V infection in children should continue to be strengthened in the future. |
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