STRUCTURAL, ANTIGENIC AND IMMUNOGENIC RELATIONSHIPS BETWEEN EUROPEAN BROWN HARE SYNDROME VIRUS AND RABBIT HEMORRHAGIC-DISEASE VIRUS

The capsid protein of a French isolate of the European brown hare synd rome virus (EBHSV) was expressed in the baculovirus system. The recomb inant EBHSV (rEBHSV) capsid protein was able to self-assemble into vir us-like particles (VLPs). The VLPs were indistinguishable from the inf ectious EBHSV and displayed morphological characteristics similar to t hose we have described for the VLPs resulting from the expression of t he capsid protein of rabbit haemorrhagic disease virus (RHDV), a close ly related calicivirus. Cross-protection experiments showed that vacci nation with rEBHSV particles did not protect rabbits against an RHDV c hallenge. A set of monoclonal antibodies (MAbs) was raised against rEB HSV capsid protein and used together with anti-RHDV and anti-EBHSV MAb s produced against native viruses to study the antigenic relationships between the two caliciviruses. All six anti-EBHSV MAbs delineated dis continuous epitopes; two of them reacted with specific surface epitope s and the remaining four reacted with internal epitopes which were als o present in rRHDV. All anti-RHDV MAbs were monospecific; th ree react ed with surface linear epitope(s), two reacted with internal linear ep itope(s) and one with a surface conformational epitope. On the basis o f all these results, a classification of RHDV and EBHSV as two serotyp es of a single serogroup is proposed.