RT Journal Article SR Electronic(1) A1 Chhabra, Preeti A1 de Graaf, Miranda A1 Parra, Gabriel I. A1 Chan, Martin Chi-Wai A1 Green, Kim A1 Martella, Vito A1 Wang, Qiuhong A1 White, Peter A. A1 Katayama, Kazuhiko A1 Vennema, Harry A1 Koopmans, Marion P. G. A1 Vinjé, JanYR 2019 T1 Updated classification of norovirus genogroups and genotypes JF Journal of General Virology, VO 100 IS 10 SP 1393 OP 1406 DO https://doi.org/10.1099/jgv.0.001318 PB Microbiology Society, SN 1465-2099, AB Noroviruses are genetically diverse RNA viruses associated with acute gastroenteritis in mammalian hosts. Phylogenetically, they can be segregated into different genogroups as well as P (polymerase)-groups and further into genotypes and P-types based on amino acid diversity of the complete VP1 gene and nucleotide diversity of the RNA-dependent RNA polymerase (RdRp) region of ORF1, respectively. In recent years, several new noroviruses have been reported that warrant an update of the existing classification scheme. Using previously described 2× standard deviation (sd) criteria to group sequences into separate clusters, we expanded the number of genogroups to 10 (GI-GX) and the number of genotypes to 49 (9 GI, 27 GII, 3 GIII, 2 GIV, 2 GV, 2 GVI and 1 genotype each for GVII, GVIII, GIX [formerly GII.15] and GX). Viruses for which currently only one sequence is available in public databases were classified into tentative new genogroups (GNA1 and GNA2) and genotypes (GII.NA1, GII.NA2 and GIV.NA1) with their definitive assignment awaiting additional related sequences. Based on nucleotide diversity in the RdRp region, noroviruses can be divided into 60 P-types (14 GI, 37 GII, 2 GIII, 1 GIV, 2 GV, 2 GVI, 1 GVII and 1 GX), 2 tentative P-groups and 14 tentative P-types. Future classification and nomenclature updates will be based on complete genome sequences and will be coordinated and disseminated by the international norovirus classification-working group., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/jgv.0.001318