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



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.



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.



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.
School of Biotechnology and Biomolecular Sciences, Faculty of Science, University of New South Wales, Sydney, Australia.|Molecular Laboratory, Department of Pathology, Singapore General Hospital, Singapore.
Kun Lee
KL
Lim
Institute of Environmental Science and Research, Kenepuru Science Centre, Porirua, New Zealand.
Joanne
J
Hewitt
School of Biotechnology and Biomolecular Sciences, Faculty of Science, University of New South Wales, Sydney, Australia.
Alefiya
A
Sitabkhan
Marie Bashir Institute for Infectious Diseases and Biosecurity, School of Biological Sciences and Sydney Medical School, University of Sydney, Sydney, Australia.
John-Sebastian
JS
Eden
School of Biotechnology and Biomolecular Sciences, Faculty of Science, University of New South Wales, Sydney, Australia.
Jennifer
J
Lun
PathWest Laboratory Medicine WA, Queen Elizabeth II Medical Centre, Perth, Australia.|School of Pathology and Laboratory Medicine, University of Western Australia, Nedlands, Australia.
Avram
A
Levy
Virology Division, SESIAHS, Department of Microbiology, Prince of Wales Hospital, Sydney, Australia.
Juan
J
Merif
PathWest Laboratory Medicine WA, Queen Elizabeth II Medical Centre, Perth, Australia.|School of Pathology and Laboratory Medicine, University of Western Australia, Nedlands, Australia.
David
D
Smith
School of Biotechnology and Biomolecular Sciences, Faculty of Science, University of New South Wales, Sydney, Australia.|Virology Division, SESIAHS, Department of Microbiology, Prince of Wales Hospital, Sydney, Australia.|School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, Australia.
William D
WD
Rawlinson
School of Biotechnology and Biomolecular Sciences, Faculty of Science, University of New South Wales, Sydney, Australia.
Peter A
PA
White
D000940:Antigenic Variation; D001315:Australia / Q000453:epidemiology; D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000821:virology*; D004196:Disease Outbreaks; D062665:Epidemiological Monitoring; D005759:Gastroenteritis / Q000453:epidemiology* / Q000821:virology*; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D009154:Mutation; D009520:New Zealand / Q000453:epidemiology; D029322:Norovirus / Q000145:classification / Q000235:genetics / Q000276:immunology; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D011995:Recombination, Genetic; D015678:Viral Structural Proteins / Q000235:genetics / Q000276:immunology
D012367:RNA, Viral; D015678:Viral Structural Proteins