Characterising the molecular epidemiology of human parechovirus in young infants in the UK and Canada.

• Most human parechovirus (HPeV) infections detected in infants were genotype 3 (HPeV-A3; 57/58 cases). • A genotype 5 strain (HPeV-A5) was detected for the first time in the U.K. • Strains of HPeV-A3 from UK and Canada were phylogenetically interspersed. • No association was seen between severity of disease and HPeV phylogenetic grouping. We evaluated the extent of virus heterogeneity in PeV infected infants in the UK, Canada and Australia. Samples were collected from PeV infected infants during 2013–16. Next generation sequencing was used to obtain sequencing data and construct phylogenetic trees based on analysis of the VP1 region. Comparison was made with sequencing data available from an outbreak in Australia. We amplified and sequenced 58 samples. All obtained PeV sequences were genotype 3 apart from one UK sample which was PeV-A5. Phylogenetic analysis revealed that all strains clustered together on the same clade and showed no significant genetic variation. We saw no significant evidence of association between sequence and either clinical severity (defined by admission to paediatric intensive care), geographical origin (compared between Canada and U.K) or year of sample collection (samples sequenced during 2013 – 2018). In this small cohort, sequencing data indicate that PeV circulating in the UK and Canada from 2013 to 18 are derived from a common ancestor. No association between disease severity and genetic sequence was seen in the UK or Canadian cohorts. Larger studies are required to support these findings. [ABSTRACT FROM AUTHOR]