Evaluation and Identification of in vitro Cellular Immune Response to Culture Filtrate Antigens of M. tuberculosis Culture. Implications for Vaccine Design
In the current study, fractions of culture filtrate proteins isolated at different time periods from M. tuberculosis sputum culture were evaluated for T cell activity (ADA, IFN-γ, TNF-α, & IL-12) using in vitro PBMC model. These isolated fractions were later on partially characterized by antibody detection assay using panel of six M. tuberculosis H37RV antigens (Ag85B, ESAT-6, CFP-10, GroES, 45 KD, and Hsp 16). Our results suggested us that PBMCs induced with culture filtrate proteins particularly those secreted towards later phase of growth curve of M. tuberculosis culture have good potential T cell activity as compared to BCG vaccine. On partial characterization we found levels of all secretary antigens increased towards later phase fractions (fraction C). Moreover on further evaluating individual purified M. tuberculosis H37RV antigens for T cell activity, we found that PBMCs induced with these antigens induces good T-cell response but not as consistent as fraction C. Thus to conclude, Culture Filtrate Proteins of M. tuberculosis sputum culture are important T-cell targets, and thus potential of such culture filtrate proteins may be further explored in near future for development of effective vaccination strategies for improving efficacy of currently available TB vaccine.