Immunological characterization of recombinant antigens isolated from a Mycobacterium avium lambda gt11 expression library by using monoclonal antibody probes.

Nontuberculous mycobacteria, particularly Mycobacterium avium, have been isolated from a significant percentage of patients with AIDS. Early detection of M. avium infection is difficult, and treatment regimens are often ineffective. Much needs to be learned about antigens and factors responsible for immunity to and pathogenesis of the disease. Specific antigens and diagnostic procedures for infection need to be developed. To address some of these problems, we have generated 25 different monoclonal antibodies against a serovar 4 strain of M. avium isolated from a patient with AIDS. Protease sensitivity studies have demonstrated that each of these antibodies recognizes a protein-associated epitope. Immunoblot analyses suggest that seven of these monoclonal antibodies react specifically with M. avium and M. intracellular epitopes. Immunoreactive bacteriophages were identified from an M. avium lambda gt11 expression library with two of these monoclonal antibodies (3808 C3 and 3954 B12). Lambda lysogens, generated from the immunoreactive bacteriophages, overproduced beta-galactosidase fusion proteins which were reactive with the two monoclonal antibodies in immunoblot assays. The purified fusion proteins were shown to elicit skin test reactions in sensitized guinea pigs.