Family: Secoviridae

Subfamily: Comovirinae

Distinguishing features

The genome of members of the subfamily Comovirinae consists of two ssRNAs with a 5ʹ-bound polypeptide (VPg) and a 3ʹ-poly(A) tail. Members of the subfamily group as a single branch in phylogenetic trees using the conserved Pro-Pol region (see family section on phylogenetic relationships and Figure 4.Secoviridae). Other genera within the family Secoviridae are more distantly related. Within the sub-family, genera are distinguished by their specific genomic organization, biological properties and phylogenetic relations. Each genus within the sub-family Comovirinae represents a single sub-branch in the Pro-Pol phylogenetic tree.

Genus demarcation criteria

The criteria demarcating genera in the subfamily are:

·       Number of genomic RNAs

·       Number of protein domains and/or processing sites within the polyprotein(s)

·       Number of CPs

·       Presence of additional ORFs and/or subgenomic RNAs

·       Clustering as a single branch in phylogenetic trees derived from amino acid sequence alignments of the conserved Pro-Pol region when compared with other genera of the family Secoviridae (Figure 4.Secoviridae). The Pro-Pol region is delineated by the “CG” motif of the 3C-like proteinase and the “GDD” motif of the polymerase. Identification of proteinase cleavage sites is not required to delineate the Pro-Pol region.

Not all criteria may need to be met simultaneously.