LcrV

lcrV is a gene found on the virulence plasmids of several pathogenic Yersinia species, including Yersinia pestis, Yersinia enterocolitica, and Yersinia pseudotuberculosis. The locus encodes the V antigen, a secreted protein that is a component of the type III secretion system (T3SS) injectisome, located at the distal end of the needle-like apparatus. The V antigen is commonly referred to as LcrV and is involved in the translocation of effector proteins from the bacterial cytosol into host cells, thereby contributing to virulence.

Functionally, LcrV forms part of the tip complex of the T3SS and is thought to facilitate recognition or delivery of virulence effectors into host cells. In addition to its structural role, LcrV influences host immune responses and can modulate inflammation, a factor that aids bacterial survival during infection. The protein is expressed under conditions that activate the T3SS, notably at mammalian temperatures and low calcium, conditions that mimic the host environment and trigger virulence gene regulation.

Regulation and genetics: lcrV is co-regulated with other yop and T3SS genes on the virulence plasmid pCD1/pYV. Expression is linked to environmental cues such as temperature and calcium concentration, aligning production of the V antigen with the infectious process.

Medical relevance: LcrV is a major target for plague vaccine research. Subunit vaccines using recombinant LcrV, often in combination with other antigens, aim to elicit protective immunity against Y. pestis. Variants of LcrV across Yersinia species have been studied for their immunogenic properties and potential cross-protection.