Identification and characterization of antigenic determinants of Mycobacterium leprae that react with antibodies in sera of leprosy patients.

Antigenic determinants of Mycobacterium leprae were identified by screening a lambda gt11::M. leprae genomic library with two separate pools of sera from leprosy patients. A total of 45 recombinant clones were detected with pooled sera from 21 lepromatous (LL) leprosy patients and 5 additional clones specified polypeptides that reacted with antibodies in pooled sera from 30 borderline tuberculoid or tuberculoid leprosy patients. The recombinant clones that specified antigenic determinants that reacted with sera from LL patients were condensed into eight groups on the basis of DNA hybridization experiments among the M. leprae DNA insert fragments. In addition, 11 of the 45 recombinant clones did not hybridize to members of the eight groups nor to one another; these represent unique recombinant clones. None of the recombinant clones identified by screening with sera from tuberculoid leprosy patients hybridized to each other or to any of the 45 LL recombinant clones. The polypeptides specified by the recombinant clones were usually fusion proteins with beta-galactosidase, ranging in size from 117 to 175 kilodaltons (kDa). Members of hybridization group III specified nonfusion proteins of 45 kDa. Only members of hybridization group I reacted with any of 30 monoclonal antibodies prepared against M. leprae proteins; recombinant proteins from these clones reacted with a single monoclonal antibody directed against the M. leprae 65-kDa protein. Thus, at least 22 new antigenic determinants of M. leprae have been identified on the basis of their reactivity to antibodies in sera from LL patients or sera from tuberculoid leprosy patients or both.