Surveillance of Norovirus contamination on scallops sold in Beijing

Abstract

Objective To monitor the contamination of Norovirus and Rotavirus in scallops sold in Beijing and analyze their genetic characteristics. Methods A total of 72 scallops were collected during November 2014 and October 2015. The digestive tissues of scallops were excised, Norovirus was enriched using the polyethylene glycol (PEG) 8000 precipitation method. The virus RNA were extracted and tested for Norovirus and Rotavirus using the real-time reverse transcription-polymerase chain reaction (RT-PCR). The capsid gene of Norovirus was amplified by the semi-nested RT-PCR. PCR products were sequenced directly. Sequence alignment was performed using BioEdit 7.0.9.0 software and the phylogenetic tree was constructed by MEGA 6.06 software. Results Among 72 scallops, Rotavirus was detected negative, and the detection rate of Norovirus was 27.8% (20/72), including 16 strains of genogroup GⅡ, 2 strains of genogroup GⅠ, and 2 strains of mixed genogroups GⅠ and GⅡ. The highest detection rate of Norovirus (61.1%, 11/18) was found in winter, and none was detected in summer. A total of 8 strains were sequenced successfully and identified as GⅡ.17 genotype. These strains all belonged to the Cluster Ⅲb branch of GⅡ.17 genotype, among which 6 strains shared 100.0% sequence similarity with strains detected in Chinese people in 2015, in Japanese people in 2016 and 2017, in water samples in South Korea in 2017 and 2018, and in oysters in Japan in 2015. Conclusion Norovirus contamination existed in some scallops sold in Beijing, eating uncooked scallops would indicate a risk of viral acute gastroenteritis