Abstract: The invention concerns a methylated immunogenic recombinant peptide sequence comprising mycobacterial heparin-binding hemagglutinin. The invention also concerns chemical and enzymatic methods for preparing such a sequence, the sequence being previously produced in a non-methylated recombinant form then methylated by post-translational modification. The invention further concerns recombinant tools, vectors and host cells for implementing post-translational enzymatic methylation of the recombinant HBHA. The invention finally concerns immunogenic compositions comprising methylated, native or recombinant HBHA, such compositions being useful for preparing vaccines against mycobacterial infections.