Antibody response to Mycobacterium tuberculosis 30 and 16kDa antigens in pulmonary tuberculosis with human immunodeficiency virus coinfection

There is urgent need for rapid diagnostic methods to identify tuberculosis among the HIV positive cases, since the mortality is high. We have isolated and evaluated the serodiagnostic potential of the 30kDa secreted antigen and 16kDa cytosolic antigen of M. tuberculosis, among the HIV-TB patients. Antibody response was studied using Enzyme linked immunosorbent assay. In the HIV-TB group, antibody was found to be 65%, 69% and 6% positive for IgG, A and M isotypes, respectively, against 30kDa. The sensitivity increased to 84%, upon combination of the results of 3 isotypes. Anti-16kDa was detected in 15% (G), 50% (A) and 3% (M) of cases. Combination of results improved the positivity to 57%. There was no difference in antibody response among the HIV-TB cases, related to CD4 counts. Thus the 30kDa antigen proved to be of diagnostic utility in HIV-TB.