Isolation and Identification of a Murine Norovirus Persistent Infection Strain in China

Zhao Na,Su Jingliang,Cao Fuyuan,Jiang Bo,He Bin,Zhang Yanshu,Li Shuang,Jianya Huan ,Yali Yang

doi:10.3389/fvets.2020.571730

Abstract

Murine Norovirus (MNV) is one of the most known viruses among viruses in mice. Because of the high prevalence of MNV in frequently used laboratory animals in biomedical researches, there is a significant impact of MNV. There may be different prevalence degrees and molecular characteristics of MNV in different regions around the world. Here, we reported an MNV strain “designated HBTS-1806” isolation from commercial mice's feces that caused a detectable cytopathic effect (CPE) in RAW264.7 cells. According to electron microscopy, the virus was 50–70 nm in diameter. The complete genome of HBTS-1806 is 7383 nucleotides with a structure similar to that of MNV reference strains. According to phylogenetic analysis on the basis of the whole genome, HBTS-1806 shared nucleotide sequence identities of 90.2–95.4% with other Chinese isolates reported. Analysis of amino acid sequence on the basis of ORF1 and ORF2 suggested that the isolated strain may be derived from recombination. Although no gross lesions or histopathological changes were found from mice infected with 5 × 105 TCLD50 of MNV by oral gavage inoculation, the intestinal virus loads lasted 12 weeks, suggesting a persistent infection strain of MNV isolate in China.

Highlights

As single-stranded and positive-sense RNA viruses, noroviruses belong to the family Caliciviridae and the genus Norovirus
Murine noroviruses consist of a group of newly-recognized pathogens that are able to infect laboratory mice
The first reported Murine Norovirus (MNV)-1 generates a transient infection with a short duration of fecal shedding after infecting immunocompetent mice in laboratory [30]

Summary

INTRODUCTION

As single-stranded and positive-sense RNA viruses, noroviruses belong to the family Caliciviridae and the genus Norovirus. Murine noroviruses (MNVs), categorized as GV, were discovered in conventionally housed mice at Washington University in a screen for novel human pathogens capable of infecting mice [5]. This MNV can propagate in the RAW 264.7 cell line originated from mouse macrophages [4, 6]. The reports showed that all MNV strains isolated from laboratory mice around the world are of single genotype with ∼13% nt and ∼7% aa diversity in the ORF2 (VP1) region, indicating very limited genetic diversity when comparing with the human noroviruses [12]. An MNV persistent infection strain from laboratory mice was identified and characterized in China

MATERIALS AND METHODS

Ethics Statement

DISCUSSION

ETHICS STATEMENT