Sero-reactivity of two different antigenic protein fractions of M.tb H37Ra excretory-secretory antigen in pulmonary and extra-pulmonary tuberculosis.
Excretory-secretory proteins of Mycobacterium tuberculosis H37Ra, have been of diagnostic interest in pulmonary (PTB) and extrapulmonary tuberculosis (EPTB). Two different excretory-secretory antigenic proteins of M.tbH37Ra viz., EST-DE1 (a 6% TCA soluble and DEAE anion exchange purified antigen) and ESAS-7 (50% ammonium sulphate solubilized and SDS-PAGE fractionated antigen) were studied in stick-indirect penicillinase ELISA for detecting tuberculous IgG antibodies in serum samples of pulmonary as well as extrapulmonary tuberculosis (tuberculous lymphadenopathy (TBLN), tuberculous meningitis (TBM), bone & joint tuberculosis (B&J TB), abdominal tuberculosis (Abd. TB) patients. The ESAS-7 antigen has shown comparatively better seroreactivity (90%) than that of EST-DE1 antigen in pulmonary tuberculosis cases. The overall specificity of 93.2% using ESAS-7 antigen was also found better compared to 86.4% obtained using EST-DE1 antigen. Further, in extra pulmonary tuberculosis group, using ESAS-7 antigen 84% (21/25) of histopathologically confirmed TBLN cases and 90% (9/10) clinically diagnosed and ATT responded TBM cases showed positive reaction for tuberculous IgG antibody. The per cent positivity using EST-DE1 antigen was however comparatively low in TBLN and TBM cases, (76% and 80% respectively). In histopathologically proven bone and joint tuberculosis and abdominal tuberculosis cases EST-DE1 antigen showed better sensitivity of 75% and 83.3% respectively in IgG antibody detection compared to that of ESAS-7 antigen (50% and 66% respectively). From the present study, it can be envisaged that ESAS-7 antigenic fraction has a good potential in the diagnosis of pulmonary and certain extra-pulmonary tuberculosis infection (TBLN & TBM) whereas EST-DE1 was found to be better in detecting specific antibodies in bone & joint and abdominal tuberculosis.
Banerjee
S
S
Jamna Lal Bajaj Tropical Disease Research Centre, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha-442 102, Maharashtra.
Nair
E R
ER
Kumar
S
S
Gangane
N
N
Reddy
M V
MV
Harinath
B C
BC
D000917:Antibody Formation; D000942:Antigens, Bacterial / Q000097:blood / Q000302:isolation & purification*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D009169:Mycobacterium tuberculosis / Q000276:immunology* / Q000378:metabolism; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000276:immunology*
D000942:Antigens, Bacterial; D007074:Immunoglobulin G