Antigen 85A (Ag85A) (Ag85A)

Antigen 85A (Ag85A), also known as fbpA or Rv3804c, is a 32 kDa secreted protein from Mycobacterium tuberculosis that plays a critical role in the bacteria's physiology and the host's immune recognition (NIH, Wikipedia). As a mycolyltransferase, Ag85A is essential for the biogenesis of the mycobacterial cell wall, catalyzing the transfer of mycolic acids to form the arabinogalactan-poly(L-glutamate-D-alanine) complex and the cord factor (NIH). Beyond its enzymatic function, Ag85A is one of the most immunodominant antigens of M. tuberculosis, making it a primary target for vaccine development (Frontiers in Immunology). It is processed by antigen-presenting cells and presented via Major Histocompatibility Complex (MHC) class I and II molecules to activate CD8+ and CD4+ T cells, respectively (PLoS ONE). This interaction with T-cell receptors (TCRs) is the basis for several candidate vaccines, most notably MVA85A, a viral vector vaccine designed to boost BCG-primed immunity (Wikipedia). Despite its strong immunogenicity, clinical trials for MVA85A have faced challenges in demonstrating significant protective efficacy, highlighting the complexity of the immune response required to prevent tuberculosis (PLoS ONE).

Other names

fbpARv3804cFibronectin-binding protein A32 kDa antigenMycolyltransferase Ag85AAntigen 85 complex A

Vaccine-mediated induction of T-cell immunity via MHC presentation of Ag85A peptides to T-cell receptors; Inhibition of mycolyltransferase activity by small molecules