Immunogenic synthetic peptides against mycobacteria of potential immunodiagnostic and immunoprophylactic value

Individuals in the acute or active stage of tuberculosis present antibodies against molecules in the range of 80KD to 50KD of molecular weight, suggesting that these proteins may not play a critical role in the defense against the infection. When treatment has been started and patients begin to recover the antibody levels against proteins between 80KD and 50KD rise. Simultaneously, in these sera appear antibodies against another group of proteins of variable molecular weight. The proteins of 43KD, 33KD and 13KD identified in sonicates of the M. tuberculosis are not found in sonicates of BCG, Pasteur sub-strain. The antigenicity study of the synthetized peptides corresponding to an amphilitic area of the 13KD molecule showed that this peptide reacted in the Dot-Blot test, with sera of patients who had recovered from tuberculosis but not with sera of patients in the acute stages of the disease, similar to what happens with the complete protein. These data strongly suggest that this epitope can be involved in the protective immune response against Mycobacterium tuberculosis. Studies on delayed type hypersensitivity (DHT) reactions show the existence of specific reactivities against the synthetic peptides. Synthetic peptides corresponding to a molecular sequence of amino acids pertaining selectively to M. tuberculosis or other mycobacteria can be used as potentially useful reagents for immunodiagnosis.