Phylogenetic analysis of rabbit haemorrhagic disease virus in France between 1993 and 2000, and the characterisation of RHDV antigenic variants.

The first molecular epidemiological study of Rabbit haemorrhagic disease virus undertaken in France between 1988 and 1995, identified three genogroups, two of which (G1, G2) disappeared quickly. We used immunocapture-RT-PCR and sequencing to analyse 104 new RHDV isolates collected between 1993 and 2000. One isolate was obtained in 2000 from a French overseas territory, the Reunion Island. The nucleotide sequences of these isolates were aligned with those of some French RHDV isolates representative of the three genogroups previously identified, of some reference strains and German and American RHDV antigenic variants. Despite the low degree of nucleotide sequence variation, three new genogroups (G4 to G6) were identified with significant bootstrap values. Two of these genogroups (G4 and G5) were related to the year in which the RHDV isolates were collected. Genogroup G4 emerged from genogroup G3, which has now disappeared. Genogroup G5 is a new independent group. The genogroup G6 contained an isolate collected in mainland France in 1999 and the isolate collected from the Reunion Island, as well as German and American RHDV variants. Multiple sequence alignments of the VP60 gene and antigenic analysis with monoclonal antibodies demonstrated that these French isolates are two new isolates of the RHDV variant.