MDR-TB Antibody Response (Western Blot) to Fractions of Isoniazid and Rifampicin Resistant Antigens of Mycobacterium tuberculosis.

Drug-resistant TB poses a major threat to control of TB worldwide. Despite progress in the detection of Multidrug-resistant TB (MDR-TB) cases, a major diagnostic gap remains: 55% of reported TB patients estimated to have MDR-TB were not detected in 2013. MDR-TB antigens were conjugated to CNBr-activated Sepharose 4B. Specific polyclonal antibodies against MDR-TB Ags were prepared in rabbits using two boosted injections of the MDR-TB antigen. The antibodies were purified and treated with susceptible TB to remove any non-specific and cross-reactive antibodies. In the present study, comparative analysis of electrophoretic pattern of different antigens of INH/RIF-resistant TB were studied for identifying protein profiles. A RIF-resistant TB antigen was shown here to have different protein profiles from INH-resistant TB isolate. The results of Western blotting analysis showed that in the RIF- and INH-resistant antigenic fractions some bands of 14.4 and 45 kDa as immunogenic were common. Moreover, four bands of RIF-resistant TB antigen fractions (16, 19, 21, and 45 KDa) and one band of INH-resistant TB (about 26 KDa) were detected as diagnostic antigens. This study suggests that the Western blot is an accurate test to survey INH- and RIF-resistant TB antigens of M. tuberculosis infection. These findings indicate that MDR-TB diagnosis (based on Ag detection) could be useful in the identification of disease stages that precede symptomatic and microbiologically positive TB, such as subclinical and incipient TB.