Mycobacterium tuberculosis antigens Antigen 85A (Ag85A), Antigen 32A (Mtb32A), and Antigen 39A (Mtb39A) (Ag85A/Mtb32A/Mtb39A)

Mycobacterium tuberculosis antigens Ag85A, Mtb32A, and Mtb39A are highly immunogenic proteins that serve as critical components in the development of subunit and viral-vectored tuberculosis vaccines. Ag85A (FbpA) is a secreted mycolyltransferase essential for the synthesis of trehalose dimycolate, a major component of the mycobacterial cell wall (UniProt P9WQP3). Mtb32A (PepA) is a 32-kDa serine protease involved in bacterial protein degradation, while Mtb39A (PPE18) is a member of the PPE family that interacts with host macrophages to modulate immune signaling (UniProt P9WIP7, UniProt P96363). These antigens are frequently combined into fusion proteins, such as the M72 candidate (comprising Mtb32A and Mtb39A), to elicit a broad and potent Th1-type immune response characterized by the production of interferon-gamma and tumor necrosis factor-alpha by CD4+ T cells (PubMed: 10531231, PubMed: 21900181). The primary therapeutic objective of targeting these antigens is to provide long-lasting protective immunity that prevents the progression of latent tuberculosis infection to active disease (NEJM, 2018, DOI: 10.1056/NEJMoa1803444). Clinical evidence suggests that vaccines incorporating these antigens can significantly reduce tuberculosis incidence in high-burden populations, addressing a major gap left by the variable efficacy of the traditional BCG vaccine.

Other names

Antigen 85AFbpAPepAPPE18Rv3804cRv0125Rv1196M72 antigenFibronectin-binding protein A

Induction of antigen-specific Th1 cell-mediated immunity, primarily involving the production of interferon-gamma and tumor necrosis factor-alpha by CD4+ T cells, to prevent or control Mycobacterium tuberculosis infection.