• Vaccine Name: M. bovis WAg520 strain
• Target Pathogen: Mycobacterium tuberculosis
• Target Disease: Tuberculosis
• Vaccine Ontology ID: VO_0000552
• Type: Attenuated vaccine
• Antigen: The antigen for this vaccine was an attenuated strain of M. bovis called WAg520, which cantains a deletion in a possible undecaprenol kinase gene (De et al., 1999).
• Preparation: WAg520 was one of four nutritionally impaired strains of M. bovis selected from 440 M. bovis mutants produced by illegitimate recombination based upon their inability to grow in minimal medium (De et al., 1999).
• Virulence: This strain, along with the other test M. bovis mutants, was shown to be avirulent for guinea pigs following the subcutaneous inoculation (De et al., 1999).
• Description: WAg520, an attenuated strain of M. bovis, has only a 2-bp deletion in a possible undecaprenol kinase gene. It is one of two nutritionally impaired strains which produced significant protection in the lungs. The other one is strain WAg522 (De et al., 1999).

Guinea pig Response

• Host Strain: Duncan-Hartley
• Vaccination Protocol: Four to eight guinea pigs per group were vaccinated by subcutaneous injection with 10^5 CFU with one of the four impaired M. bovis strains or BCG. Ten animals were not vaccinated (control) (De et al., 1999).
• Side Effects: No delayed-type hypersensitivity reactions observed prior to inoculation with mycobacteria (De et al., 1999). Authors were unable to determine if nutritionally-impaired mutants influenced the development of necrotizing lesions in the lungs (De et al., 1999).
• Challenge Protocol: All animals were anesthetized eight weeks post-vaccination via intramuscular injection with 3 mg ketamine hydrochloride, followed by 10x2 CFU virulent M. bovis WAg201 introduced through mouth into the trachea via cannula. Three guinea pigs which were not challeged received 10^5 CFU of each of the four strains via subcutaneous innoculation (De et al., 1999).
• Efficacy: Significant differences in lung CFU were observed between vaccinated groups and WAg520 & WAg522 strains (De et al., 1999). WAg520 elicited 0.92, 3.83, and 2.47 log10 increases in lung, splenic, and liver tissues, respectively (Table I, (De et al., 1999)). Macroscopic lesions were decreased in WAg520 recipients versus both non-vaccinated (significant different) and BCG-vaccinated (not significantly different) animals (Table 2, (De et al., 1999)).
• Description: All animals were sacrificed 13 weeks post-vaccination.