Serodiagnostic potentialities of enzyme-linked immunosorbent assay (ELISA) using mannophosphoinositides of Mycobacterium tuberculosis H37Rv

Induction of immunity against experimental tuberculosis with mycobacterial mannophosphoinositides encapsulated in liposomes containing lipid A

Mycobacterial mannophosphoinositides (PIMs) encapsulated in liposomes made of egg phosphatidylcholine (EPC) and cholesterol (CH) (2:1.5 molar ratio) were able to induce humoral and delayed type hypersensitivity (DTH, foot-pad swelling reaction) responses in mice without the help of any carrier protein. Animals immunized with this glycophospholipid antigen demonstrated enhanced percent survival on intravenous challenge with virulent M. tuberculosis. On fractionation of PIMs, pentamannophosphoinositide (PIM5) was found to induce higher antibody and DTH reaction and proved to be more immunoprotective than other fractions. Inclusion of lipid A as immunomodulator in liposomes containing PIMs or PIM5 resulted in a significantly increased immune response. Further, mice immunized with PIMs or PIM5 in lipid A-containing liposomes exhibited decreased mortality on challenge with M. tuberculosis H37Rv, which was comparable to BCG vaccinated animals.

Detection of mannophosphoinositide antigens in sputum of tuberculosis patients by dot enzyme immunoassay

A simple and economical dot ELISA for the detection of mannophosphoinositide antigen in sputum samples of tuberculosis patients has been developed using affinity-purified antibodies. This test is able to detect free as well as bound antigen. Sputum samples from 94 patients suffering from tuberculosis and 30 non-tuberculosis patients were screened and an overall sensitivity and specificity of 89% and 93.3%, respectively, was obtained. The sensitivity of the test among the different groups of tuberculosis patients did not vary significantly.

Comparative evaluation of the diagnostic significance of circulating immune complexes and antibodies to phosphatidylinositomannosides in pulmonary tuberculosis by enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay was developed to detect circulating immune complexes (CIC) and antibodies to phosphatidylinositomannosides (PIM) of mycobacteria for the diagnosis of pulmonary tuberculosis. Identification of PIM in CIC of smear and culture positive (SPCP) cases revealed 88% sensitivity and antibodies to PIM were detected in circulation in 94% cases. The smear negative and culture positive (SNCP) group had 67% positivity with regards to PIM in CIC and 83% for antibodies to PIM in circulation. In the smear negative and culture negative (SNCN) group, 40% samples were found to have PIM in CIC and 20% exhibited antibodies to PIM. The high degree of sensitivity was observed with both antigen detection in CIC and antibodies to PIM in circulation.