Modulation of Trehalose Dimycolate and Immune System by Rv0774c Protein Enhanced the Intracellular Survival of in Human Macrophages Cell Line.

Rv0774c protein was reported previously to express under stress conditions. Therefore, gene was cloned and expressed in , a surrogate host, to determine its role in bacterial persistence and immune modulation in natural environment. The bacterial colonies expressing () were larger, smoother, more moist, and flatter than the control ones (Ms_ve). Enhanced survival of Ms_rv0774c after treatment with streptomycin was observed when compared with control. The cell envelope of Ms_rv0774c was demonstrated to have more trehalose di-mycolate (TDM) and lesser amount of mycolylmannosylphosphorylheptaprenol (Myc-PL) in comparison to control. Higher intracellular survival rate was observed for as compared to in the THP-1 cells. This could be correlated to the reduction in the levels of reactive NO and expression. Infection of macrophages with resulted in significantly increased expression of TLR2 receptor and IL-10 cytokines. However, it lowered the production of pro-inflammatory cytokines such as IL-12, TNF-α, IFN-γ, and MCP-1 in infected macrophages in comparison to the control and could be associated with decreased phosphorylation of p38 MAPK. Though, predicted with high antigenicity index bioinformatically, extracellular in nature and accessible to host milieu, Rv0774c was not able to generate humoral response in patient samples. Overall, the present findings indicated that Rv0774c altered the morphology and streptomycin sensitivity by altering the lipid composition of as well as modulated the immune response in favor of bacterial persistence.