Genetic analyses of norovirus GII.4 variants in Finnish children from 1998 to 2013.

Infect Genet Evol

Vaccine Research Center, School of Medicine, University of Tampere, Biokatu 10, FI-33520 Tampere, Finland.

Published: August 2014

AI Article Synopsis

  • Noroviruses (NoVs), particularly the GII.4 genotype, are the leading causes of gastroenteritis outbreaks in children, with new variants emerging every 2-3 years due to changes in the virus's P2 domain.
  • A study in Finland from 1998 to 2013 identified 829 GII.4 cases among 1495 NoV positive specimens, revealing twelve different variants, many of which were also found in global outbreaks.
  • The research suggests that GII.4 remains the dominant strain in Finland, highlighting the need for future vaccines to target specific variants or provide broader protection against multiple variants.

Article Abstract

Noroviruses (NoVs) are the major causative agents of acute gastroenteritis (AGE) in outbreaks and in sporadic AGE in young children. Since the mid-1990s, NoV genotype GII.4 has been predominant worldwide. New GII.4 variants appear every two to three years, and antigenic variation is focused on the highly variable protruding domain (P2) of the NoV capsid protein which contains the receptor-binding regions. We studied NoV GII.4 variants in cases of endemic AGE in Finnish children from 1998 to 2013. Fecal specimens were collected from cases of AGE followed prospectively in rotavirus vaccine trials from 1998 to 2007, and from children seen at Tampere University Hospital because of AGE from 2006 to 2013. Partial capsid sequences were identified with RT-PCR and sequenced allowing P2 domain alignment and phylogenetic comparison of different GII.4 strains, with virus-like particles (VLPs) developed as candidate vaccines. Of 1495 NoV positive specimens 829 (55%) were of the GII.4 genotype, and altogether twelve GII.4 variants were identified. Identical GII.4 variants were detected in outbreaks of NoVs worldwide. A phylogenetic tree of the amino acid changes in the P2 region showed nine variants that arose over time. Our data indicates that GII.4 continues to be the predominant NoV genotype circulating in the Finnish community, and the changes in the P2 domain over time result in the development of new variants that cause AGE in children. Future NoV vaccines should either induce type specific immunity for each variant or, alternatively, induce broadly reactive protective immunity covering multiple variants.

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http://dx.doi.org/10.1016/j.meegid.2014.05.003DOI Listing

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