Mycobacterium tuberculosis PPE family protein PPE18 (PPE18)

Mycobacterium tuberculosis PPE family protein PPE18 (Rv1196) is a member of the Pro-Pro-Glu (PPE) family, which is unique to mycobacteria and localized primarily to the cell wall. It plays a pivotal role in the survival of M. tuberculosis within the host by modulating the immune system; specifically, it binds to the host Toll-like receptor 2 (TLR2) on macrophages, leading to the upregulation of the anti-inflammatory cytokine IL-10 and the subsequent suppression of pro-inflammatory Th1 responses [1][2]. This interaction aids the bacteria in evading the host's antimicrobial defenses and maintaining a latent infection. Due to its high immunogenicity and presence across various Mtb clinical isolates, PPE18 is a core component of the M72/AS01E recombinant subunit vaccine, which has shown promise in preventing the progression from latent to active tuberculosis in clinical trials [3][4]. Understanding PPE18's function is essential for both the development of preventative vaccines and potential therapeutic strategies aimed at blocking Mtb-mediated immune suppression [5].

Other names

Rv1196Mtb PPE18PPE protein 18Mtb protein Rv1196

PPE18 acts as a vaccine antigen in M72/AS01E to induce a robust memory T-cell response (CD4+ and CD8+) and protective immunity against Mycobacterium tuberculosis. Pathologically, it functions as a TLR2 agonist on host macrophages to trigger anti-inflammatory signaling pathways.