LAUSR

European brown hare syndrome (EBHS) is lethal to several species of free-living hares worldwide. The genetic characterization of its virus (EBHSV) strains in European circulation and epidemiological knowledge of EBHSV infections is not yet complete. The study determined the nucleotide sequences of the genomes of EBHSV strains from Poland and analyzed their genetic and phylogenetic relationships to a group of hare lagoviruses. The genome of five virus strains detected in Poland between 1992 and 2004 was obtained by RT-PCR and sequencing of the obtained amplicons. The genetic relationships of the EBHSV strains were analyzed using the full genome and VP60 gene sequences. Additionally, the amino acid sequence of the VP60 gene was analyzed to identify mutations specific to recognized EBHSV subgroups. Partial amplification of the virus open reading frame (ORF)1 and ORF2 regions obtained nearly complete nucleotide genome sequences of the EBHSV strains. Phylogenetic analysis placed them in a GII.1 cluster with other European strains related to nonpathogenic hare caliciviruses. VP60 gene analysis allocated these EBHSV strains to the G1.2, G2.2–2.3 or G3 virus genetic groups. The amino acid sequence differences in the entire genome ranged from 1.1 to 2.6%. Compared to a reference French EBHSV-GD strain, 22 variable amino acid sites were identified in the VP60 region of the Polish strains, but only six were in VP10. Single amino acid changes appeared in different sequence positions among Polish and other European virus strains from different genetic groups, as well as in VP10 sequences of nonpathogenic hare caliciviruses. The results of the study showed a high genetic homogeneity of EBHSV strains from Poland despite their different location occurrence and initial detection times. These strains are also phylogenetically closely related to other EBHSV strains circulating in Europe, likely confirming the slow evolutionary dynamics of this lagovirus species.