Self-assembly, antigenicity, and immunogenicity of the rabbit haemorrhagic disease virus (Czechoslovakian strain V-351) capsid protein expressed in baculovirus.

Abstract

Rabbit haemorrhagic disease virus (RHDV) capsid protein was expressed in a baculovirus system. Analysis of the expressed product showed that the recombinant protein, which is 60 kDa in size, was antigenic as revealed by its reactions in ELISA and Western blot with the antibodies raised against RHDV. Direct electron microscopy of the cell culture supernatant and the purified protein demonstrated that the capsid protein expressed in insect cells self-assembled to form empty virus-like particles (VLP) which are similar in size and morphology to that of native virus. These particles were immunoreactive with polyclonal anti-RHDV antibodies and with four monoclonal antibodies which recognise conformational epitopes of the virus. The results indicated that the VLPs were morphologically and antigenically indistinguishable from native virus. The recombinant VLPs induced high levels of RHDV-specific antibodies in rabbits and mice following immunisation. The immune response to the VLPs protected the rabbits following challenge with the virulent RHDV. In haemagglutination assays, the VLPs bound to human red blood cells similar to the native virus particles. The recombinant protein and or VLPs is suitable for the development of a rapid, sensitive and reliable test for detection of antibodies to RHDV and for use as a vaccine for domestic rabbits.