Identification of B- and T-cell epitopes within the MTP40 protein of Mycobacterium tuberculosis and their correlation with the disease course.
Synthetic peptides derived from the amino acid sequence of MTP40, a recently characterized Mycobacterium tuberculosis protein, were tested by two different immunological assays in 91 individuals. For the purposes of this study, the population was distributed in four groups: active tuberculosis (TBC) patients with elevated bacillus loads (BK+), active TBC patients with low bacillus loads (BK-), healthy individuals living in the same household with tuberculous patients (HH), and normal individuals, who had presumably never been in contact with the bacilli (control). We found that T cells of individuals belonging to the HH group showed the highest and most frequent recognition of these peptides in a T-cell proliferation assay, while their antibodies showed the lowest recognition of these peptides when tested by enzyme-linked immunosorbent assay. In contrast, TBC patients revealed an inverse pattern of immune response. Interestingly, one of these peptides (P7) was recognized by T cells of 64% of the HH individuals and by 4.5% of normal donors. Another peptide (P4) was recognized by 55% of sera from BK+ patients and by 5.5% of normal donors. The results presented here indicate the existence of T- and B-cell epitopes within the MTP40 protein. Given the particular recognition pattern of this protein, added to the fact that it appears to be a species-specific antigen of M. tuberculosis, a detailed study of the immune response to it may be useful in the design of more accurate diagnostic tests and an improved vaccine against human TBC.
Falla
J C
JC
Instituto de Inmunología, Hospital San Juan de Dios, Bogotá, Colombia.
Parra
C A
CA
Mendoza
M
M
Franco
L C
LC
Guzmán
F
F
Forero
J
J
Orozco
O
O
Patarroyo
M E
ME
D000595:Amino Acid Sequence; D000907:Antibodies, Bacterial / Q000276:immunology; D000918:Antibody Specificity; D000942:Antigens, Bacterial / Q000737:chemistry / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D001426:Bacterial Proteins; D000939:Epitopes; D006801:Humans; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D010455:Peptides / Q000737:chemistry; D013601:T-Lymphocytes / Q000276:immunology*; D014376:Tuberculosis / Q000276:immunology; D010738:Type C Phospholipases
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D000939:Epitopes; D010455:Peptides; D010738:Type C Phospholipases; C101028:MpcA protein, Mycobacterium tuberculosis