• Vaccine Name: BCG expressing MSP
• Target Pathogen: Mycobacterium tuberculosis
• Target Disease: Tuberculosis
• Vaccine Ontology ID: VO_0004107
• Type: Live, attenuated vaccine
• Antigen: MSP, a 30-kDa major secretory protein or mycolyltransferase, is used as vaccine antigen (Horwitz et al., 2000).
• Preparation: Recombinant BCG (rBCG30) was prepared using E.coli/mycobacteria shuttle plasmid pSMT3. Plasmid was electoporated into the wild-type M. bovis BCG Tice strain. The 30-kDa MSP was isolated from the subcultured strains and further processed prior to inclusion in the vaccine (Horwitz et al., 2000).

Guinea pig Response

• Host Strain: Hartley, 250-350g outbred male
• Challenge Protocol: Animals were challenged nine weeks after first injection or skin testing via aerosol with 10-ml single-cell suspension containing 1x10^5 CFU (1st & 2nd experiment) or 2x10^5 CFU (3rd experiment) of M. tuberculosis Erdman, providing ~40 to 80 liver bacilli to lungs, respectively (Horwitz et al., 2000).
• Efficacy: The highly susceptible guinea pig model of pulmonary TB, a model noteworthy for its close resemblance to human TB, was used for testing. Animals immunized with the recombinant BCG vaccine and challenged by aerosol with a highly virulent strain of M. tb. had 0.5 log fewer M. tb. bacilli in their lungs and 1 log fewer bacilli in their spleens on average than animals immunized with their parental conventional BCG vaccine counterparts. Statistically, the difference was highly significant. At necropsy, animals immunized with the recombinant BCG vaccine had fewer and smaller lesions in the lung, spleen, and liver and significantly less lung pathology than animals immunized with the parental BCG vaccine (Horwitz et al., 2000).