Pandemic GII.4 Sydney and Epidemic GII.17 Kawasaki308 Noroviruses Display Distinct Specificities for Histo-Blood Group Antigens Leading to Different Transmission Vector Dynamics in Pacific Oysters.

Vasily Morozov,Franz-Georg Hanisch,K Mathias Wegner,Horst Schroten

doi:10.3389/fmicb.2018.02826

Abstract

Noroviruses are the major cause of foodborne outbreaks of acute gastroenteritis, which are often linked to raw oyster consumption. Previous studies have suggested histo-blood group antigens (HBGA)-like structures in the oyster tissues as ligands for norovirus binding and persistence. To better understand how oysters function as vectors for the most common human noroviruses, we first tested the ability of the norovirus strains GI.1 West Chester, the pandemic GII.4 Sydney, and the epidemic GII.17 Kawasaki308 strains to interact with oyster tissues. Secondly, we explored how the HBGA preferences of these strains can affect their persistence in oyster tissues. We found limited HBGA expression in oyster tissues. HBGAs of A and H type 1 were present in the digestive tissues and palps of the Pacific oyster Crassostrea gigas, while the gills and mantle lacked any HBGA structures. By using Virus-like particles (VLPs), which are antigenically and morphologically similar to native virions, we were able to demonstrate that VLPs of GI.1 West Chester norovirus reacted with the digestive tissues and palps. Despite of the lack of HBGA expression in mantle, dominant GII.4 Sydney strain readily bound to all the oyster tissues, including the digestive tissues, gills, palps, and mantle. In contrast, no binding of the epidemic GII.17 Kawasaki308 VLPs to any of the investigated oyster tissues was observed. In synthetic HBGA and saliva-binding assays, GI.1 reacted with A type, H type, and Leb (Lewis b) HBGAs. GII.4 Sydney VLPs showed a broad binding pattern and interacted with various HBGA types. Compared to GI.1 and GII.4 VLPs, the GII.17 Kawasaki308 VLPs only weakly associated with long-chain saccharides containing A type, B type, H type, and Leb blood group epitopes. Our findings indicate that GI.1 and GII.4 noroviruses are likely to be concentrated in oysters, by binding to HBGA-like glycans, and therefore potentially leading to increased long term transmission. In regards to the GII.17 Kawasaki308 strain, we suggest that oysters can only function as short term transmission vector in periods of high environmental virus concentrations.

Highlights

Noroviruses are non-enveloped single stranded RNA viruses of the Caliciviridae family
Human noroviruses are genetically and antigenically diverse (Hansman, 2006), with a majority of the human norovirus infections being caused by the GII strains
Most of the norovirus genotypes which infect humans have been found in oyster-related outbreak samples

Summary

Introduction

Noroviruses are non-enveloped single stranded RNA viruses of the Caliciviridae family. According to the most recent classification, there are seven genogroups (GI- GVII) in the norovirus genus (Vinjé, 2015). Noroviruses of the GI and GII genogroups have been detected in humans. Most norovirus infections over the past decade have been caused by genogroup II genotype 4 (GII.4) noroviruses. The GII. variants are responsible for six pandemics and for the majority of sporadic outbreaks worldwide (Noel et al, 1999; Widdowson et al, 2004; Bull et al, 2006; Eden et al, 2010, 2014; Yen et al, 2011). A novel GII. strain has emerged in Asia, causing an alarming number of infections and gradually replacing GII. strains (Chan et al, 2015a; Zhang et al, 2015; Koromyslova et al, 2017)

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