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

In the amino acid (AA) sequences of α 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 α antigen from Mycobacterium scrofulaceum (S-α). AAs288-300 of S-α fused to β- galactosidase was reactive with the antisera raised against S-α. The same fused peptide did not react with the antisera raised against the α antigen from Mycobacterium avium (A-α) and Mycobacterium bovis BCG (B-α). B-cell epitope mapping then was performed focusing on the C-terminal region of S-α using the synthetic peptides. Their reactivities with antisera raised against the α 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 cross-reactive common epitopes in mycobacterial species. And AAs291-300 were reactive only with the antisera raised against S-α. This region may possess a species- specific epitope.