Screening of a recombinant mycobacterial DNA library with polyclonal antiserum and molecular weight analysis of expressed antigens.

A lambda gt11 expression library containing recombinant DNA from Mycobacterium tuberculosis was screened using hyperimmune anti-M. tuberculosis rabbit serum. The majority (22 of 29) of the recombinant clones selected by using polyclonal serum expressed three antigens that were previously identified by using mouse monoclonal antibodies, thus indicating the immunodominance of these proteins. Western blot analysis of the recombinant clones demonstrated that expression of these antigens is frequently independent of the formation of beta-galactosidase fusion proteins. The molecular weight of each expressed antigen can vary between clones and is not necessarily identical to that found in mycobacterial extracts.