A group of norovirus experts within NoroNet has proposed a phylogeny based classification of noroviruses for both ORF1 and VP1 (ORF2) genotypes and a standardized strain nomenclature (Archives of Virology, in press).

ORF1 and VP1 typing

As recombination is common in noroviruses, and the recombination hotspot is the ORF1/ORF2 (VP1) overlap region, typing norovirus sequences on either side of this overlap is useful for identification. The consensus nomenclature proposed in NoroNet has been made  available in the norovirus typing tool.

Strain nomenclature

The strain name should be written as follows:

organism/                            norovirus GI, norovirus GII, etc.
host/                                    Hu, Bo, Po etc. see below
country code (ISO)/             FR, DE, US,  JP, etc.
year of sampling/ 
genogroup and genotype/  GII.P4_GII.4, or if only the  ORF2 sequence
(ORF1 and VP1)                   is known: GII.4
name                                   city , if necessary followed by a serial number

For example:  norovirus GII/Hu/FR/2004/GII.Pg_GII.1/Paris23, norovirus GII/Hu/GB/2010/GII.P4_GII.4_NewOrleans2009/London48, or if only the capsid sequence is known: norovirus GII/Hu/FR/2004/GII.12/Paris25.

List of host name abbreviations
hu     human
po     porcine
bo     bovine
ca     canine
mu    murine
ra      rat
ov     ovine