Abstract
LcrV of Yersinia pestis is a major protective antigen proposed for inclusion in subunit plague vaccines. One way that anti-LcrV antibody is thought to protect is by inhibiting the delivery of toxins called Yops to host cells. The present study characterizes the relation between this inhibition and the phagocytosis of the bacteria. J774A.1 cells were infected with Y. pestis KIM5 in the presence of a protective polyclonal anti-LcrV antibody or a nonprotective polyclonal anti-YopM antibody, and delivery of YopH and YopE into the cytoplasm was assayed by immunoblotting. The ability to inhibit the delivery of these Yops depended upon having antibody bound to the cell surface; blocking conditions that prevented the binding of antibody to Fc receptors prevented the inhibition of Yop delivery. Anti-LcrV antibody also promoted phagocytosis of the yersiniae, whereas F(ab')(2) fragments did not. Further, anti-LcrV antibody could not inhibit the delivery of Yops into cells that were unable to phagocytose due to the presence of cytochalasin D. However, Yops were produced only by extracellular yersiniae. We hypothesize that anti-LcrV antibody does not directly inhibit Yop delivery but instead causes phagocytosis, with consequent inhibition of Yop protein production in the intracellular yersiniae. The prophagocytic effect of anti-LcrV antibody extended to mouse polymorphonuclear neutrophils (PMNs) in vitro, and PMNs were shown to be critical for protection: when PMNs in mice were ablated, the mice lost all ability to be protected by anti-LcrV antibody.
Highlights
V antigen, or LcrV, of Yersinia pestis is a multifunctional virulence protein that is planned for inclusion in the generation of plague vaccines currently under development [26, 27]
Pettersson et al found that anti-LcrV antibody could partially inhibit Yop-dependent rounding up of HeLa cells [15], while Weeks et al had found that anti-LcrV antibody would inhibit YopJ-mediated apoptosis of J774A.1 cells after infection with Y. pestis CO92 [29], and we recently corroborated their findings with Y. pestis KIM5 [16]
This work was part of an ongoing effort in our laboratory to improve our understanding of LcrV activities in the pathogenesis of Y. pestis and clarify how antibody against it protects against plague
Summary
V antigen, or LcrV, of Yersinia pestis is a multifunctional virulence protein that is planned for inclusion in the generation of plague vaccines currently under development [26, 27]. Tissue culture cells intoxicated by Yops are unable to mobilize their actin cytoskeletons to engulf the yersiniae due to the synergistic effects of four of the Yops (YopH, -E, and -T and YpkA) [3, 8]. This is thought to be a major antiphagocytic mechanism that the yersiniae use to prevent killing by polymorphonuclear neutrophils (PMNs) and macrophages. We hypothesized that antibody acted to inhibit the delivery of Yops Consistent with this idea, anti-LcrV antibody was not able to enhance the clearance of a Y. pestis multiple-Yop mutant that is able to assemble a functional Ysc system and express and secrete LcrV but lacks the genes for the six effector Yops. We demonstrated that PMNs are the predominant mediator of protection by antiLcrV antibody against plague in mice
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
