Genome of astroviruses: location of the diagnostic regions A to C

Lineage classification scheme

Canonical human astroviruses (HAstVs) are important enteric pathogens and can be classified genetically and antigenically into eight types. Sequence analysis of small diagnostic regions at either the 5’ or 3’ end of ORF2 (capsid precursor) is a good proxy for prediction of HAstV types and for distinction of intra-typic genetic lineages (sub-types). Upon sequence and phylogenetic analysis of the full-length ORF2 of nearli 95 HAstV strains selected from the databases and/or sequenced ex novo, a detailed classification of HAstV types 1 to 6 into lineages has been proposed and updated (Martella et al., 2014; Medici et al., 2015). The classification scheme was integrated in a novel nomenclature system suitable for designation of HAstV strains.

Table: Reference strains proposed for each lineage according to a lineage classification scheme based on the analysis of the full-length ORF2.

*For types 7 and 8 no lineages were determined.

Nomenclature for ORF2 lineages

In the attempt to be consistent with HAstV literature, nomenclature for ORF2 lineages followed the schemes used in previous studies, i.e. HAstV type-xy, where x is a romanic number indicating the (sero)type assignment and y is a lower-case letter, indicating the genetic lineage (sub-type). Examples of this nomenclature system are herewith indicated

ITA/2009/PR5142/type-2d, a type-2 strain of lineage d

DEU/2004/Dresden/type-1a, a type-1 strain of lineage a