Mycobacterium tuberculosis Ag85b:hfcγ1 recombinant fusion protein as a selective receptor-dependent delivery system for antigen presentation.

Introducing an effective vaccine for tuberculosis (TB) is an urgent need. Mycobacterium tuberculosis (Mtb) Ag85 complex is suggested for making protective immunodominant antigens for design and development of novel TB vaccine. In the present study, a pDR2EF1-Fcγ1 vector has been used to make Ag85B:hFcγ1 recombinant fusion protein. Briefly, specific XbaI and NotI site incorporated primers were used to amplify Mtb-fbpB gene by PCR, TA-cloned and amplified in E.coli DH5α. The resulting vector then subcloned into the pDR2EF1.Fcγ1 vector and transferred to Chinese hamster ovary (CHO) cell line. DNA sequencing was performed to confirm that Ag85B:hFcγ1 construct is precise and in-frame. Then, Ag85B:hFcγ1 protein was produced by CHO expression system and recombinant protein was purified using HiTrap rProtein A Sepharose Fast Flow column. The presence of recombinant fusion protein confirmed by immunofluorescence (IFA) and Western blotting (WB). This fusion protein containing Fc fragment of human IgG1, apart from stability and adjuvanticity potential, could bind to FcRγI (CD64) on the surface of antigen-presenting cells (APCs) and induce cross-presentation in favour of host immune response and can be used as a potential candidate along with other subunit vaccines against Mtb.