A HIGHLY IMMUNOGENIC PUTATIVE MYCOBACTERIUM-KANSASII LIPOPROTEIN

The resurgence of tuberculosis, the emergence of multiple drug resista nt tuberculosis, and the increasing prevalence of mycobacterial diseas e in AIDS patients have increased the importance of defining new mycob acterial antigens that can be utilized in the development of improved diagnostic reagents and more effective vaccines. In this report, a hig hly immunogenic Mycobacterium kansasii protein (MK35) and the gene enc oding this antigen were characterized. MK35 gene probes reacted with g enomic DNA from M. avium, M. bovis BCG, M. intracellulare and M. tuber culosis but not with DNA isolated from nine other mycobacterial specie s. Nucleotide sequence analysis showed that the MK35 gene encodes a 26 kDa protein which contains a consensus bacterial lipoprotein processi ng sequence. In addition, detergent-phase separation studies strongly suggested that MK35 is a lipoprotein. Skin test assays demonstrated th at MK35 elicited a strong response in guinea pigs sensitized with M. k ansasii but did not read in M. tuberculosis-sensitized guinea pigs. Th ese results further suggest that mycobacterial lipoproteins are immuno genic antigens that should be considered in the development of new myc obacterial vaccines and diagnostic reagents.