Enhancing Mycobacterium tuberculosis-Ag85B immunogenicity by fusing with human Fcγ1 (Ag85B:hFcγ1)

Area of Science:

• Immunology
• Vaccine Development
• Microbiology

Background:

• Tuberculosis (TB) remains a significant global health threat.
• Mycobacterium tuberculosis (Mtb) Ag85 is a key target for TB vaccine development due to its immunogenicity.
• Enhancing the immunogenicity of Mtb antigens is critical for effective TB vaccines.

Purpose of the Study:

• To create and assess the immunogenicity of a novel fusion protein, Ag85B:hFcγ1, for TB vaccine development.
• To investigate the potential of fusing Mtb Ag85B with the human IgG1 Fc fragment (hFcγ1) to boost immune responses.
• To evaluate the capacity of Ag85B:hFcγ1 to induce a Th1-biased cell-mediated immunity (CMI).

Main Methods:

• The Ag85B:hFcγ1 fusion protein was designed, produced using the Pichia pastoris expression system, and purified.
• Protein production and purity were confirmed via ELISA and Western blotting.
• Immunogenicity was assessed in a mouse model, including co-localisation assays and measurement of cytokine production (IFN-γ, IL-17).

Main Results:

• The Ag85B:hFcγ1 fusion protein was successfully produced and confirmed for purity.
• Co-localisation assays demonstrated that Ag85B:hFcγ1 binds to hFcγRI (CD64), suggesting targeted antigen presentation.
• Immunisation in mice led to significantly higher IFN-γ production, indicating a robust Th1 cell-mediated immune response.

Conclusions:

• The Ag85B:hFcγ1 fusion protein demonstrates enhanced immunogenicity compared to previous constructs, likely due to improved antigen presentation via Fc-mediated targeting of CD64.
• The observed high IFN-γ production suggests potential for developing more effective TB vaccines.
• Further research may explore the role of glycosylation and Fc fusion in optimizing vaccine efficacy against TB.