| ObjectiveTo investigate the genotype distribution and evolution of norovirus(NV)in children with acute gastroenteritis(AGE)under 5 years old,and to analyze the clinical differences of infection among different genotypes of NV and the influencing factors on the severity of the illness.To provide a scientific basis and reference for the prevention and control of the disease and vaccine development.Methods(1)Collecting 570 fecal samples from children under 5 years old who met the diagnostic criteria for viral diarrhea in Kunming Children’s Hospital from October 2020 to April 2021,and corresponding clinical information was recorded.Reverse Transcription-Polymerase Chain Reaction(RT-PCR)was used to amplify VP1 region of fecal NV samples,and the positive products were sent to gene companies for purification and sequencing.The sequencing results were compared by BLAST function in NCBI database,and MEGA7.0 was used to construct phylogenetic tree in this region.(2)Through systematic retrospective study,the appropriate statistical method was adopted to analyze the clinical characteristics of NV infection of different genotypes.We constructed the GII genome NV standard plasmid and amplified the NV-positive samples by Realtime Fluorescence Quantitative Polymerase Chain Reaction(RT-q PCR).The standard curve of Ct value and virus copy number was drawn,and the corresponding standard curve equation was obtained,and the virus copy number of NV positive samples was calculated.Comprehensive clinical data,the influence factors of the severity of age children were analyzed.Results(1)A total of 570 fecal samples were included in this study,and 203 samples were positive for NV,with a detection rate of 35.61%(203/570),37.72%(129/342)for males,32.46%(74/228)for females,and a sex ratio of 1.74:1 for males.There was no significant difference in the detection rate of NV between male and female(P>0.05).(2)The detection rates of NV in five age groups were 32.98%(63/191),34.75%(98/282),40.82%(20/49),48.65%(18/37)and 36.36%(4/11)in 0-12,13-24,25-36,37-48 and 49-60 months,respectively.There was no significant difference in the detection rate of NV among different age groups(P>0.05).In this study,161 children with the AGE of onset were less than 2 years old,accounting for 79.31%(161/203),and the proportion of NV positive components from 13 to 24 months was the highest,accounting for 48.28%(98/203).(3)All the NVs detected in this study were GII genomes.According to different VP1 regions,five genotypes were identified,including GII.4(55.17%,112/203,),GII.3(36.45%,74/203),GII.2(6.41%,13/203),GII.6(0.49%,1/203)and GII.8(1.48%,3/203).(4)The main clinical manifestations of 179 NV-positive cases were diarrhea(85.47%),vomiting(83.24%),fever(30.73%),dehydration(16.76%),convulsion(11.73%)and abdominal pain(4.47%).There was significant difference in age distribution between GII.3 and other NVs(adjusted P<0.05).The difference between GII.4 and GII.3 types of NVs in the occurrence of pneumonia was statistically significant(P<0.05).There were statistically significant differences in the distribution of GII.4,GII.3 and other non-epidemic genotypes of NVs in children with moderate and severe disease(P<0.05).(5)Correlation analysis was conducted on the factors affecting the severity of disease in children with AGE.Univariate analysis showed that the severity of disease in children with AGE had statistical significance in age,dehydration,convulsions and pneumonia(P<0.01).Multivariate Logistic regression analysis showed that AGE,dehydration,convulsions and pneumonia were independent factors influencing the severity of age in mild and severe cases(OR=1.071,0.058,0.201,0.092,P<0.05);AGE and convulsion were independent factors influencing age severity compared with moderate and severe disease(OR=1.068,0.068,P<0.05).Spearman correlation analysis showed no significant correlation between disease severity and NV copy number(P>0.05).Conclusions(1)The predominant strain of NV in this region was GII.4,which was closely related to the 2019 Yunnan strains(MN588306 and MN588307).The second type was GII.3,which was closely related to the 2018 Beijing strains(MW205640),and its detection rate was higher than that of 2018.(2)This study found that children infected with GII.3 NV were more seriously ill and more likely to develop pneumonia,suggesting that clinical attention should be paid to the changes in the disease of children infected with GII.3 NV.(3)This study found that in addition to Vesikari scale evaluation indexes,the severity of AGE conditions can also be comprehensively evaluated according to the age of children and the occurrence of dehydration,convulsions,and pneumonia,so as to select a reasonable treatment plan. |
PDF Full Text Request