| Objective:to study the etiological epidemic characteristics of norovirus acute gastroenteritis in Xianju and its correlation with blood routine and fecal routine.Molecular epidemiological analysis of norovirus in Xianju area.The structure analysis of intestinal flora under norovirus infection,and based on the structure of intestinal flora,to further analyze the effect of norovirus infection on intestinal flora,and to explore the value of intestinal flora in the case of norovirus infection.It provides a scientific basis for formulating prevention and control strategies according to local conditions and reducing the exposure risk of the population,and lays a foundation for the prediction,early warning and control of the epidemic situation.Methods:① All samples of patients were analyzed for Norovirus etiology by RT-PCR technology,and correlation analysis was made with the data of blood routine(white blood cell,lymphocyte ratio,HS-CRP)and fecal routine(microscopic leukocyte,occult blood test).②High-throughput gene sequencing was used to analyze norovirus genotypes in norovirus positive samples,and an evolutionary tree was constructed.③ 16SrDNA sequencing was used to analyze the intestinal core flora of patients with norovirus.ANOVA test and Metastats difference analysis were used to study the effect of acute gastroenteritis infected by norovirus on intestinal flora.Results:① 39 cases of norovirus infection were detected in 289 diarrhea samples,with a total positive rate of 13.49%,NoVGI type was detected in 2 cases(0.70%),NoVGII type was detected in 37 cases(12.89%),norovirus infection was significantly correlated with local climate temperature,and the incidence was high in winter and spring.The positive rate of occult blood test in fecal routine test was 34.61%,and the positive rate of leukocyte(>3/per visual field)was 35.90%under high power microscope(40 X 10).According to the results of norovirus detection,the patients were divided into norovirus infection group and non-norovirus infection group.the results of fecal routine occult blood test and leukocyte microscopic examination and the changes of leukocyte count,lymphocyte percentage and HS-CRP level in blood routine were compared between the two groups.It was found that the positive rate of occult blood test in norovirus infection group was significantly lower than that in children with non-viral acute gastroenteritis,and there was no significant difference between the two groups(p<0.05).120 qualified blood routine samples were collected from 289 patients.It was found that there was no significant difference in blood routine items between the two groups at the age of ≤5 years old.In the age group>5 years old,except that the lymphocyte ratio of norovirus infection group was higher than that of non-norovirus infection group,there was no significant difference in other items between the two groups(p<0.05).② High-throughput sequencing of norovirus positive samples from February 2021 to January 2022 was carried out against the vip1 region.29 strains were successfully sequenced,divided into 7 genotypes,mainly NoVsGII.4(37.93%)and NoVsGII.6(24.14%),followed by NoVsGII.2(13.79%)and NoVsGII.3(10.35%),while NoVsGII.17(6.9%),(6.9%)and(6.9%)were the least.Evolutionary analysis showed that the seven genotypes were evolutionarily stable.NoVsGI.3 and MT492003(Spain,2020),OK147889(Zhejiang,China,2019)and MZ470610(India,2019)belong to the same evolutionary strain.NoVsGI.5 and MK12173(Sichuan,China)are in the same branch.NoVsGII.4 has three relatively independent evolutionary branches in GII,which is similar to MW205666 strain in Beijing,MW20564 and MW205567 strain in Beijing,China.NoVsGII.6 genotype and MK789460(Shanghai,China)strain belong to the same clade,NoVsGII.2 and MF802549(Nanjing,China),MW205567(Beijing,China),OK095361(OK095361)belong to the same clade,NoVsGII.3 and MT093377(Shenzhen,China)belong to the same evolutionary branch.NoVsGII.17 belongs to the same branch as KP335155(Shanghai strain in China),KY424350(Gaithersburg strain in the United States)and GQ266696(Swiss strain).All the strains detected can find strains with similar affinity,belonging to the same epidemic strain,and there is no variation.③At the family level,the intestinal flora of acute gastroenteritis infected by Norovirus is mainly composed of unclassified Bacteroides,Bacteroides,Spirillaceae,Rumen Fungi,Prevodiaceae,and Veronella,while at the genera level,it is mainly composed of unclassified bacteria,Bacteroides,Clostridium pullulans,Rosella and Prevosiella,but there is no significant difference in the a diversity of intestinal flora(ANOVA analysis,p<0.05).The structure of core flora changed,and statistical analysis of flora abundance showed that the genera of Bacillus,Burkholderia,Clostridium,Flavobacterium,Flavobacterium,Fluviicola and Spirillum in Norovirus infection group were significantly higher than those in non-Norovirus infection group.Prevotella was detected separately in Norovirus infection group,indicating that there may be iconic bacteria in infection.Conclusion:① From February 2021 to January 2022,norovirus mainly broke out in autumn and winter,and the positive results of occult blood test in fecal routine and the increase of lymphocyte ratio in blood routine of patients over 5 years old were beneficial to the diagnosis of norovirus diarrhea.② From February 2021 to January 2022,norovirus in Xianju was mainly distributed with GII genotype,and the main epidemic strain was GII.4 subtype,and there were five evolutionary branches of type G1I,which were close to the surrounding outbreak strains,and there were no new variant strains,and the epidemic situation of different genotypes was relatively stable.③Norovirus acute gastroenteritis has a certain effect on the structure of intestinal flora,and there may be iconic bacteria in intestinal flora that respond to norovirus infection. |
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