Below are some preliminary guidelines which we are using to help us decide if a new virus belongs to an existing genus or if it should be classified in a new genus. These may change/evolve as more information becomes available.

1) The Leader, 2A, 2B and 3A polypeptides would normally be expected to be homologous between members of a genus.

2) Members of a genus should normally share a structurally homologous internal ribosome entry site (IRES) (i.e. the same IRES type). This rule may not apply if rule 1 is true. [Note: Members of different genera may share the same IRES type.]

3) Members of a genus should normally share phylogenetically related P1, P2 and P3 genome regions, each sharing >40%, >40% and >50% amino acid identity, respectively.