Type III secretion system protein V antigen (V antigen)

Type III secretion system protein V antigen, commonly known as V antigen (LcrV in Yersinia spp. and PcrV in Pseudomonas aeruginosa), is a highly conserved component of the type III secretion system (T3SS), a complex nanomachine that allows gram-negative bacteria to inject virulence effector proteins directly into eukaryotic host cells[4][5]. The V antigen is primarily located at the tip of the secretion needle and is essential for the assembly and function of the translocon, the structure that forms a pore in the host membrane for effector delivery[4][5]. The presence and function of V antigen are central to pathogenicity and host immune modulation in serious bacterial infections such as plague (caused by Yersinia pestis) and infections by Pseudomonas aeruginosa. V antigen is a validated target for antibody-based therapies that aim to block T3SS-mediated cytotoxicity and raise protective host immunity. No small-molecule drugs are currently approved for this target, but several monoclonal antibodies and vaccine candidates are being evaluated.

Other names

LcrVV antigenLow calcium response V antigenPcrV (in Pseudomonas aeruginosa)YscV (in Yersinia)Needle-tip protein (context-dependent)

Neutralization of protein-protein interaction (e.g., antibody blocks V antigen function, prevents effector protein delivery into host cells[4]); Inhibition of translocon assembly/needle tip complex