Analysis on gene of norovirus from sporadic diarrhea cases in Hebei province

Abstract

Objective To understand the molecular characteristics of norovirus strains from acute sporadic diarrhea cases in Hebei province. Methods From September 2015 to December 2016, stool specimens of sporadic diarrhea cases were collected from the sentinel hospitals of 6 cities in Hebei province. Norovirus was detected by real-time reverse transcription polymerase chain reaction (RT-PCR). The gene fragments of the virus in positive samples were amplified and sequenced for sequence alignments to determine the genotypes. The sequences obtained by sequencing were used in similarity analysis with the reference sequences in norovirus gene database. The phylogenetic tree was used for the analysis. Results A total of 1 240 stool specimens of diarrhea cases were collected. Fifty-eight samples were positive for noroviruses, including 5 cases of genotype GI and 53 cases of GII. The norovirus RNA fragments in the positive samples were sequenced, and 21 sequences of capsid protein 1 (VP1) region and 17 sequences of RNA-dependent RNA polymerase (RdRp) region were obtained. After comparing with the reference sequences of norovirus in Genbank database, the sequences of VP1 revealed five genotypes. The predominant type was GII.4 (10/21) followed by GII.17 (4/21) and other genotypes of GII.2 (3/21), GII.3 (3/21) and GII.6 (1/21). Two genoytpes by RdRP sequences were discovered, including GII.P17 (4/17) and GII.Pe (13/17). Conclusions Norovirus GII.4 and GII.17 were predominant among sporadic diarrhea cases in Hebei province, and other types also existed. The surveillance should be enhanced for timely detection of new type of the virus. Key words: Norovirus; Diarrheal case; Genotyping