A Multi-Site Study of Norovirus Molecular Epidemiology in Australia and New Zealand, 2013-2014

PLoS One. 2016 Apr 26;11(4):e0145254. doi: 10.1371/journal.pone.0145254. eCollection 2016.

Abstract

Background: Norovirus (NoV) is the major cause of acute gastroenteritis across all age groups. In particular, variants of genogroup II, genotype 4 (GII.4) have been associated with epidemics globally, occurring approximately every three years. The pandemic GII.4 variant, Sydney 2012, was first reported in early 2012 and soon became the predominant circulating NoV strain globally. Despite its broad impact, both clinically and economically, our understanding of the fundamental diversity and mechanisms by which new NoV strains emerge remains limited. In this study, we describe the molecular epidemiological trends of NoV-associated acute gastroenteritis in Australia and New Zealand between January 2013 and June 2014.

Methodology: Overall, 647 NoV-positive clinical faecal samples from 409 outbreaks and 238 unlinked cases of acute gastroenteritis were examined by RT-PCR and sequencing. Phylogenetic analysis was then performed to identify NoV capsid genotypes and to establish the temporal dominance of circulating pandemic GII.4 variants. Recombinant viruses were also identified based on analysis of the ORF1/2 overlapping region.

Findings: Peaks in NoV activity were observed, however the timing of these epidemics varied between different regions. Overall, GII.4 NoVs were the dominant cause of both outbreaks and cases of NoV-associated acute gastroenteritis (63.1%, n = 408/647), with Sydney 2012 being the most common GII.4 variant identified (98.8%, n = 403/408). Of the 409 reported NoV outbreaks, aged-care facilities were the most common setting in both Western Australia (87%, n = 20/23) and New Zealand (58.1%, n = 200/344) while most of the NoV outbreaks were reported from hospitals (38%, n = 16/42) in New South Wales, Australia. An analysis of a subset of non-GII.4 viruses from all locations (125/239) showed the majority (56.8%, n = 71/125) were inter-genotype recombinants. These recombinants were surprisingly diverse and could be classified into 18 distinct recombinant types, with GII.P16/GII.13 (24% of recombinants) the most common.

Conclusion: This study revealed that following its emergence in 2012, GII.4 Sydney 2012 variant continued to be the predominant cause of NoV-associated acute gastroenteritis in Australia and New Zealand between 2013 and 2014.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigenic Variation
  • Australia / epidemiology
  • Caliciviridae Infections / epidemiology*
  • Caliciviridae Infections / virology*
  • Disease Outbreaks
  • Epidemiological Monitoring
  • Gastroenteritis / epidemiology*
  • Gastroenteritis / virology*
  • Genotype
  • Humans
  • Molecular Epidemiology
  • Mutation
  • New Zealand / epidemiology
  • Norovirus* / classification
  • Norovirus* / genetics
  • Norovirus* / immunology
  • Phylogeny
  • RNA, Viral / genetics
  • Recombination, Genetic
  • Viral Structural Proteins / genetics
  • Viral Structural Proteins / immunology

Substances

  • RNA, Viral
  • Viral Structural Proteins

Grants and funding

This project is partially funded through an Australian NHMRC Project Grant APP1083139. The New Zealand component of this study was funded by the New Zealand Ministry of Health, as part of ESR’s contract to provide disease surveillance services. KLL acknowledges support through an FY10 SGH Formal Education Scholarship from Singapore General Hospital Pte. Ltd. JL is supported by an Australian Postgraduate Award and a Water Research Australia Scholarship. JSE is supported by an NHMRC Early Career Fellowship (1073466). The funders did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.