Emergence of GII.e as a major ORF 1 norovirus genotype and its associated ORF 2 GII.4 variant forms.
The noroviruses are a major cause of outbreaks of gastroenteritis. The norovirus genotype "GII.e", identified by ORF (Open Reading Frame) 1 nucleotide sequencing, appears to be an obligatory recombinant, in that no unique GII.e ORF 2 genotype has been identified. In 2012 GII.e norovirus became the predominant ORF 1 genotype in norovirus outbreaks in Victoria, Australia, and the current study documents changes in the ORF 1 region of GII.e norovirus since it first emerged in 2008, as well as in the ORF 2 genotypes associated with GII.e norovirus. GII.e norovirus underwent significant genetic change in ORF 1 between 2010 and 2012 and this genetic change corresponded to a significant increase in the prevalence of the virus. Nucleotide sequencing of the ORF 2 region of GII.e specimens showed that in 2008-2009, all the ORF 2 sequences corresponded to the GII.4 (2007) variant, in 2010 all the ORF 2 sequences corresponded to the GII.4 (2012-like) variant and in 2012 all the ORF 2 sequences corresponded to the GII.4 (2012) variant, the GII.4 (2012-like) variant, or the GII.4 (2009-like) variant. The evidence indicated that the development of the 2012 GII.e epidemic strains was due to evolutionary change rather than a novel recombination event. The results also support the notion that ORF 1 is critical in determining the virulence of a norovirus strain.
Victorian Infectious Diseases Reference Laboratory, North Melbourne, Victoria, Australia.
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Bruggink
Victorian Infectious Diseases Reference Laboratory, North Melbourne, Victoria, Australia.
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Dunbar
Victorian Infectious Diseases Reference Laboratory, North Melbourne, Victoria, Australia. Electronic address: john.marshall@mh.org.au.
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Marshall
D000595:Amino Acid Sequence; D017250:Caliciviridae Infections / Q000821:virology*; D004196:Disease Outbreaks; D005243:Feces / Q000821:virology; D005838:Genotype; D006801:Humans; D008969:Molecular Sequence Data; D029322:Norovirus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D016366:Open Reading Frames / Q000235:genetics*; D010802:Phylogeny; D012367:RNA, Viral / Q000032:analysis / Q000235:genetics; D016415:Sequence Alignment
D012367:RNA, Viral
Evolution; Norovirus; Recombination