Molecular etiological characteristics of the gastroenteritis outbreak associated with norovirus infection in Guangyuan city, Sichuan province

Objective To investigate the genotype and genetic characteristics of the pathogens associated with the epidemic outbreak of acute gastroenteritis(AGE) in Guangyuan city, Sichuan province. Methods Eighteen stool samples and 15 anal swab samples from 4 AGE outbreaks were collected from Feb 2017 to May 2017. Norovirus (NoV) nucleic acid was detected by Real-time PCR method , and the positive samples were amplified by conventional reverse transcription-polymerase chain reaction (RT-PCR) and nucleotide sequencing. Results Four AGE outbreaks were all caused by NoV. And 20 (60.6%) samples were positive for NoV GⅡ. Gene sequence comparison and phylogenetic analysis showed that 4 AGE outbreaks were all caused by GⅡ.P16/GⅡ.2 NoV. All the strains of GⅡ.P16/GⅡ.2 NoV shared high homology in nucleotides. One of the outbreaks was caused by GⅡ.P16/GⅡ.2 and GⅡ.P7/GⅡ.14 NoV co-infection. Conclusions The 4 outbreaks of AGE in Guangyuan city, Sichuan province were major caused by GⅡ.P16/GⅡ.2 NoV, meanwhile GⅡ.P16/GⅡ.2 and GⅡ.P7/GⅡ.14 NoV co-infection existed. Key words: Norovirus; Gastroenteritis; Outbreak; Phylogenetic analysis