PHYLOGENETIC ANALYSIS OF RABBIT HEMORRHAGIC-DISEASE AND EUROPEAN BROWN HARE SYNDROME VIRUSES BY COMPARISON OF SEQUENCES FROM THE CAPSID PROTEIN GENE

A 398 bp fragment of the capsid protein (VP60) gene of 39 clinical sam ples of rabbit haemorrhagic disease virus (RHDV) and 17 of European br own hare syndrome virus (EBHSV), collected between 1981 and 1995 from 17 countries, was amplified by PCR and directly sequenced. The alignme nt of the nucleotide sequences and the subsequently constructed phylog enetic tree clearly separated RHDV from EBHSV as phylogenetic entities . The nucleotide homology rates between the RHDV and EBHSV groups rang ed between 52.6% and 60.0%. The homology rates within the groups were much higher, 89.4% to 100% for the RHDV samples, and 89.4% to 100% for the EBHSV specimens. No intermediate viruses were found. Despite the high homology, three main branches could be identified in the phylogen etic tree of the RHDV samples, corresponding to the epizootiological d ata, while the EBHSV dendrogram did not show such well defined branche s. The present results support the classification of RHDV and EBHSV as two distinct members of the Caliciviridae family. Nevertheless, a com parison with previously determined sequences of other caliciviruses sh ows that RHDV and EBHSV are more closely related to each other than to any other calicivirus.