Stable expression and secretion of the B-cell epitope of rodent malaria from Mycobacterium bovis BCG and induction of long-lasting humoral response in mouse

The live bacterial vaccine Mycobacterium bovis BCG (BCG) is a vehicle worth noticing for various protective antigens. The gene encoding the B-cell epitope of the oligopeptide repeating in the circumsporozoite protein (C.S. protein) of the rodent malaria parasite, Plasmodium yoelii, was inserted into the plasmid vector under the control of an expression cassette carrying the promoter and signal sequence of the a antigen derived from Mycobacterium kansasii (k-a). The B-cell epitope was successfully expressed and secreted from BCG as a fusion protein with k-a. This recombinant BCG was administered subcutaneously into BALB/c mice and the antibody production was measured by the enzyme-linked immunosorbent assay (ELISA). Long lasting humoral response was found in one of seven mice.