Immunological Characterization of α Antigen of Mycobacterium kansasii: B-Cell Epitope Mapping

Mapping of B-cell epitopes on α antigen of Mycobacterium kansasii (K-α) was carried out by using recombinant truncated K-α fusion peptides. We observed that two immunodominant B-cell epitopes (amino acids 222–268 and 267–306) and one minor epitope (amino acid 249–286) were located in the C-terminal region of K-α. The other three minor B-cell epitopes were mapped in N-terminal (amino acids 80–98 and 99–166) and central (amino acid 174–204) regions of K-α. All defined epitopes were common to Mycobacterium tuberculosis and M. kansasii . Besides these common epitopes, a region in K-α (amino acid 290–319) revealed different reactivities between antibodies against K-α and α antigen of M. tuberculosis . These findings may provide a basis for development of serodiagnosis that can distinguish between M. kansasii and M. tuberculosis infections.