Detection and genetic analysis of new GII.17norovirus variant from infantile diarrhea in Nanjing

OBJECTIVE To investigate new GII.17norovirus（NoV）variant infection status and indentify its genetic characteristics in Nanjing,so as to provide references for disease control and prevention and vaccine development.METHODS A total of 178 stool specimens were collected from the outpatient children with acute diarrhea admitted to the Nanjing Maternity and Child Health Care Hospital in Nanjing from Jan.to Jun.2015.NoV genegroups were detected by real-time PCR（RT-PCR）,and genotypes were determined by sequence analysis.RESULTS Among 178 stool specimens,27（15.2%）cases were positive for NoV GII,and GI was not found.Genotype study was conducted by analyzing the nucleotide sequence of capsid gene.Based on capsid region,14 strains were new GII.17 variants,8strains were GII.3and 5strains were GII.4-Sydney,respectively.Furthermore,we amplified VP1 gene of five variants and compared with epidemic strains in amino acid sequence.All of them had mutations in some key sites in amino acid sequence,which were closely related to form neutralizing epitopes and population susceptibility.CONCLUSION The new GII.17 norovirus variant had been detected in young children with infantile viral diarrhea in Nanjing,which detection rate was higher than other norovirus variants,and it might have become the dominant strain of NoV.Considering that it had already triggered epidemic in China,the monitoring of this novel GII.17 variant will be a crucial part of NoV surveillance in Nanjing.