Species-specific B-cell epitope on the C-terminal region of the alpha antigen from Mycobacterium scrofulaceum

In the amino acid (AA) sequences of alpha antigen from mycobacteria, C-terminal regions were variable among a variety of mycobacterial species though the N-terminal regions were relatively conserved. These regions may possess some species-specific antigenic determinants of the alpha antigen from Mycobacterium scrofulaceum (S-alpha). AAs288-300 of S-alpha fused to beta-galactosidase was reactive with the antisera raised against S-alpha. The same fused peptide did not react with the antisera raised against the alpha antigen from Mycobacterium avium (A-alpha) and Mycobacterium bovis BCG (B-alpha). B-cell epitope mapping then was performed focusing on the C-terminal region of S-alpha using the synthetic peptides. Their reactivities with antisera raised against the alpha antigens of three different mycobacterial species were assessed by ELISA. AAs279-286 were a cross-reactive common immunodominant region among three mycobacterial species. This region may be one of the crossreactive common epitopes in mycobacterial species. And AAs291-300 were reactive only with the antisera raised against S-alpha. This region may possess a species-specific epitope. (C) 1997 Academic Press Limited.