Distinctive western blot antibody patterns induced by infection of mice with individual strains of the Mycobacterium avium complex.

Systemic infection of mice with organisms of the Mycobacterium avium complex (MAC) induced antibody responses, characteristic for each of the three tested individual strains. The influence of host genetic factors was reflected up to 3 months after infection by the finding of generally oligobanded and multibanded Western blot patterns in C57B1/6 and BALB/c mice, respectively. Nevertheless, more bands developed at 6 months in C57BL/6 mice. The response to three antigens of 18,000, 38,000 and 24,000 MW was analysed in greater detail. Antibodies to a protease-resistant 18,000 MW band produced only by BALB/c mice were either strain specific, following infection with M. avium, strain Maa-B2, or cross-reactive within MAC, following infection with M. avium strain Maa-A6 and M. paratuberculosis, strain Map-203. Another protease-resistant antigen of 38,000 MW was immunogenic only in Maa-B2 infected mice. This constituent was found to be related to the protease-sensitive antigen of corresponding molecular weight from M. tuberculosis. Two 24,000 MW proteins of M. paratuberculosis were separated by two-dimensional gel electrophoresis: antibodies to the anodic band were induced by Map-203 infection, whilst the cathodic band was revealed by heteroclitic antibodies from Maa-B2-infected mice. The latter antigen is apparently expressed during in vivo replication, but not during in vitro culture of Maa-B2 bacteria. We generally conclude, that the selective antibody patterns after live infection, could be attributed to differences in the release of native antigens within mycobacterial lesions. In view of a high degree of species specificity, some of the immunogenic constituents identified may also be useful for serodiagnostic application.