Two secreted
antigens of
Mycobacterium tuberculosis, namely the
antigen 85 complex (30/31) and 38kDa
antigens, were purified from the whole
culture filtrate by using two dimensional preparative
electrophoresis and
anion exchange
chromatography, respectively. Individual components of the
antigen 85 complex namely,
antigen 85A, 85B and 85C, were
separated using
hydrophobic interaction chromatography. The humoral antibody activity to these
antigens in
sputum positive cases of active
pulmonary tuberculosis and normal
healthy volunteers was determined by
enzyme linked immunosorbent assay (
ELISA) and immunoblot. Recombinant 38kDa and
antigen 6 were used as reference
antigens for the assay. None of the
healthy volunteers reacted with the 38kDa
antigen, while 52% of the TB sera reacted with it. Of the three components of the
antigen 85 complex, 85B gave the highest positivity of 40 per cent. The results of combination of 38kDa with
antigen 6 offered better results with 76% positivity.