Science Bite - 3 min Oral Presentation (Students and ECRs only) Lorne Infection and Immunity 2020

The burden of rotavirus disease and genotypic diversity in children and adults in the vaccine-era in Australia (#53)

Celeste M Donato 1 2 3 , Susie Roczo-Farkas 1 , Elena Demosthenous 1 3 , Carl D Kirkwood 1 2 4 , Daniel Cowley 1 2 , Graeme L Barnes 1 2 5 , Ruth F Bishop 1 2 , Nada Bogdanovic-Sakran 1 , Karen Boniface 1 , Julie E Bines 1 2 5
  1. Enteric Diseases, Murdoch Children's Research Institute, Parkville, Victoria, Australia
  2. Department of Paediatrics, University of Melbourne, Parkville, Victoria , Australia
  3. Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, Australia
  4. Enteric and Diarrheal Diseases, Global Health , Bill & Melinda Gates Foundation, Seattle, Washington, USA
  5. Department of Gastroenterology and Clinical Nutrition, Royal Children’s Hospital, Parkville, Victoria, Australia

Background

Group A rotaviruses are a major cause of gastroenteritis in young children worldwide, with the burden in older children and adults underappreciated. The vaccines Rotarix and RotaTeq were introduced in Australia in 2007, with a state-based selection until 2017, after which Rotarix was solely used. High vaccine coverage has been reported in Australia which may act as a selective pressure impacting strain diversity. The aim of this study was to describe the distribution and diversity of rotavirus genotypes before and after vaccine introduction in Australia.  

 

Methods

The Australian Rotavirus Surveillance Program conducted genotypic analysis on rotavirus-positive samples from children <5 years (n=15,332, 1995-2018) and children ≥5 years and adults (n= 2650, 2010-2018) hospitalised with gastroenteritis. Rotavirus G and P genotypes were determined using serological and hemi-nested multiplex RT-PCR assays. Whole genome sequencing was performed on rare genotypes.

 

Results

In the pre-vaccine era (1995–2006), G1P[8] was the dominant genotype in children <5 years. Following vaccine introduction (2007–2018), genotype dominance fluctuated annually with a greater genotypic diversity observed. A substantial burden of disease was revealed in the population ≥5 years; particularly in children 5-14 years and the elderly. Overall, G2P[4] the dominant genotype in the population ≥5 years; with minor alterations in genotype distribution observed across age groups. Genotype distribution varied based on the vaccine implemented in the paediatric population; with G12P[8] dominant in RotaTeq states, and equine-like G3P[8] and G2P[4] dominant in Rotarix states. This pattern was observed in children <5 years and older age groups. Unusual genotypes were detected across all age groups. Whole genome sequencing revealed G6P[14], G10P[14], and G8P[14] strains exhibiting genes of bovine origins. G3P[3] and G3P[9] strains exhibited genes of canine, feline and pteropine origins. 

 

Conclusions

In the vaccine-era, there has been an increase in the diversity of rotavirus genotypes. Marked differences were observed in genotype dominance between RotaTeq and Rotarix states. The vaccines may exert different immunological pressures that influence the diversity of rotavirus strains circulating in Australia across age groups. This study highlights the continued need for rotavirus surveillance across the population, despite the implementation of efficacious vaccines.