Genetic variability among astroviruses was observed, and this confirms previous results from the USA and Europe [5, 18, 19] . For ORF1b of TAstV-2, two subgroups could be distinguished. In subgroup 1, three subclades were identified. All six Polish TAstV-2 isolates clustered in subclade a together with North American isolates of group 1 identified by Pantin-Jackwood at al. and astroviruses from group 2 identified by Jindal at al. [4, 12, 18] . Subclade b included North American isolates from group 2 identified by Pantin-Jackwood et al. and from group 1 identified by Jindal et al. as well as TAstV from Italian group G1. In our comparison, AstV isolates from guinea fowl from Italy that were previously assigned to the G3 group and isolates from France (sequences available in GenBank) also clustered in subclade b, but in separate sublineages. Subgroup 2 included only European isolates originating from Italy (isolated in 2004/05) and Poland (2008) . Italian isolates from this subgroup were previously described as a distinct genetic lineage, G2 [4] . A similar subgrouping of European and ''American-like'' isolates of TAstV-2 was previously indicated by Maurel at al. [15] . However, the comparison of sequences of Polish and French TAstV strains was not possible, since the sequences were not available in the public domain.