Toll-like receptor-mediated immune response to dormancy-associated mycobacterium tuberculosis antigen Rv2659c

Abstract

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) poses a major threat to the global public health. Importantly, latent tuberculosis infection (LTBI) still impedes the elimination of TB incidence since it has a substantial risk to develop active disease and become infectious. A multi-stage subunit vaccine comprising active and latency antigens of Mtb has been raised as the promising vaccine to trigger immune protection against all stages of TB. However, discovery of new antigens is still required to provide the better fusion proteins. While current research mainly focuses on the adaptive immune induction ability of vaccine candidates, the knowledge in innate immune response is still limited. This thesis characterized the potential ability in stimulating innate immune response of the recombinant dormancy-associated Mtb protein Rv2659c. The immune recognition was significantly initiated at 400 ng/ml and 800 ng/ml of protein Rv2659c compared to the negative control in HEK-Blue™ hTLR2 and HEK-Blue™ hTLR4 systems respectively. Protein Rv2659c subsequently increased the signal of phosphorylated NF-κB p65 (Ser536) overtime in the human CD14+ monocytes. In addition, this protein induced the cytokine production (IL-1β, TNF-α, IL-6, IL-10 and IL-8) in a dose dependent manner (400 ng/ml to 6.4 µg/ml) in human peripheral blood mononuclear cells (hPBMCs). Those cytokines were produced via TLR2 and TLR4 signaling pathways in hPBMCs proven by performing 5 µg/ml of anti-hTLR2 and anti-hTLR4 antibodies. Therefore, this insight knowledge emphasized the capability of alternative fusion protein in multi-stage subunit vaccine development. IMPLICATION OF THE THESIS The knowledge of dormancy-associated Mycobacterium tuberculosis protein Rv2659c in triggering TLR-mediated innate immune response would be benefit for the alternative protein selection of a multi-stage subunit vaccine against tuberculosis.