Oral Presentation 9th Australasian Virology Society Meeting 2017

Comprehensive Molecular Epidemiological Study of Norovirus with Multiple Sample Types (#39)

Jennifer H Lun 1 , Alefiya Sitabkhan 1 , John-Sebastian Eden 2 , Natalie E Netzler 1 , Daniel Enosi Tuipulotu 1 , Leigh Morrell 1 , Richard Jones 3 , Kelly-Anne Ressler 4 , Mark J Ferson 4 5 , Dominic E Dwyer 6 , Jen Kok 6 , William D Rawlinson 7 8 , Daniel Deere 9 , Nicholas D Crosbie 10 , Peter A White 1
  1. School of Biotechnology and Biomolecular Sciences, Faculty of Science, University of New South Wales, Sydney, NSW, Australia
  2. School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Sydney, NSW, Australia
  3. Douglass Hanly Moir Pathology, Macquarie Park, Sydney, NSW, Australia
  4. Public Health Unit, South Eastern Sydney Local Health District, Sydney, NSW, Australia
  5. School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW, Australia
  6. Institute for Clinical Pathology and Medical Research, NSW Health Pathology, Westmead Hospital and University of Sydney, Sydney, NSW, Australia
  7. SaViD (Serology and Virology Division), Department of Microbiology, Prince of Wales Hospital, Sydney, NSW, Australia
  8. School of Medical Sciences, Faculty of Medicine, School of Biotechnology and Biomolecular Sciences, Faculty of Science and School of Women's and Children's Health, University of New South Wales, Sydney, NSW , Australia
  9. Water Futures Pty Ltd, Sydney, NSW, Australia
  10. Melbourne Water Cooperation, Docklands, Victoria, Australia

Norovirus (NoV) is estimated to cause 677 million annual cases worldwide, resulting in over 210,000 deaths. Despite the identification of more than 36 genotypes, viruses of the genogroup II, genotype 4 (GII.4) lineage have historically caused over 70% of all NoV infections, with pandemic variants arising approximately every 3 years. Viral gastroenteritis is generally self-limiting and thus only a small proportion of symptomatic individuals present to medical facilities. Therefore, clinical samples only provide a partial representation of all circulating NoV strains in the population. Over the past decade, next generation sequencing (NGS) technologies have revolutionised viral genomic sequencing, such that the availability and cost-effectiveness of NGS now allows us to study viral genetic diversity in complex samples such as wastewater.

Using Illumina MiSeq and Sanger sequencing, we aimed to conduct a molecular surveillance of circulating NoV genogroups and genotypes within Sydney, Australia during 2016. Importantly, NoV diversity was compared between clinical and wastewater samples to identify potential pandemic variants and novel recombinant viruses and the timing of their emergence. Furthermore, monthly genome levels of NoV GII strains in wastewater were also assessed using qRT-PCR as a means to track the pathogen load in the population.

We identified the emergence of four new recombinant NoVs: two new GII.4 Sydney recombinants (GII.P4 New Orleans 2009/GII.4 Sydney 2012 and GII.P16/GII.4 Sydney 2012), GII.P12/GII.3 and GII.P16/GII.2. The prevalence of the original pandemic GII.4 Sydney 2012 variant significantly decreased in both clinical and wastewater samples over 2016. In addition, the average monthly NoV GII genome levels were 1.2 x 106 and 1.35 x 107 genome copies/L for Bondi and Malabar wastewater treatment plants, respectively. 

In summary, this study demonstrates that the combined use of clinical and wastewater samples provides a more complete picture of circulating NoV in the population, identifying both asymptomatic and symptomatic infections.