The lgt11 expression system has been employed to identify M. avium complex (MAC) antigens that may be useful in the diagnosis of MAC disease. We previously created a lgt11 gene library from a M. avium strain cultured from an AIDS patient. In the past year, we have generated and characterized 25 anti-M. avium monoclonal antibodies. Western analysis with 15 different mycobacterial sonic extracts have shown that four of these antibodies recognize determinants present only in M. avium and three react only with epitopes in the MAC. In addition, four of these monoclonal antibodies do not react with M. tuberculosis antigens. We have screened the M. avium lgt11 library with several of these antibodies. Bacteriophages expressing recombinant fusion proteins for the 26, 30, 33 and 70 kDa antigens of M. avium have been isolated and characterized. E. coli lysates containing the 26 and 33 kDa recombinant proteins induced in vitro proliferation of T cells from sensitized mice. Furthermore, HPLC-purified 26 and 33 kDa recombinant proteins induced significant skin test responses in sensitized guinea pigs. However, the skin test reactions were non-specific. We are currently evaluating the immunoreactivity of the 30 and 70 kDa M. avium fusion proteins. Peptides derived from these immunoreactive recombinant mycobacterial antigens have potential as monospecific reagents for diagnosing MAC disease.
