Abstract
Expression vectors containing rabies virus nucleoprotein B-cell and T-cell epitopes in
Mycobacterium bovis BCG were constructed. The epitopes were subcloned into the
M. leprae 18-kDa gene to ensure correct presentation to the host immune system. Expression of the 18-kDa::B+T epitope fusion protein was driven by either the
hsp60 promoter, which is constitutively activated at a high level in
M. bovis BCG, or the 18-kDa promoter, which is strongly induced in vivo. Mice were immunised intra-peritoneally with the recombinant BCG cultures and compared to a control group vaccinated with the commercial rabies vaccine Rai-SAD. Both of the expression vectors elicited a higher antibody titre than that of the rabies vaccine, with the highest response shown by
M. bovis BCG (pUP203), expression controlled by the 18-kDa promoter. Immunisation with
M. bovis BCG (pUP202), expression controlled by the
hsp60 promoter, resulted in a continuously increasing antibody titre up to 60 days post immunisation. The mice antibodies were also capable of recognising the whole rabies virus and not only the synthetic peptide epitopes.