Bacillus anthracis and Yersinia pestis vaccine antigen complex (PA/LFn-F1/V)

The target described represents a vaccine strategy rather than a single molecular entity, focusing on the activation of the host immune system against Bacillus anthracis and Yersinia pestis. This approach utilizes the anthrax Protective Antigen (PA) and the non-toxic N-terminal fragment of Lethal Factor (LFn) as a molecular syringe to deliver Y. pestis antigens, specifically the Fraction 1 (F1) capsular protein and the V (LcrV) antigen, into host cells (Kushner et al., 2003). Once inside, these antigens are processed and presented via Major Histocompatibility Complex (MHC) pathways, specifically enhancing MHC Class I presentation to CD8+ T cells alongside the standard MHC Class II presentation to CD4+ T cells (Williamson et al., 2005). The resulting immune response is characterized by high titers of neutralizing antibodies against the anthrax toxin and the plague's capsular and type III secretion components, as well as robust cellular immunity (Smiley, 2008). This multivalent targeting is critical for defense against aerosolized biothreat agents where rapid and comprehensive protection is required. Clinical development in this area focuses on recombinant fusion proteins and DNA-based delivery systems to ensure safety and immunogenicity without the risks associated with live-attenuated vaccines.

Other names

Anthrax-Plague multivalent vaccine antigensPA-LFn delivery systemF1-V plague antigensProtective Antigen (PA)Lethal Factor N-terminus (LFn)Fraction 1 (F1) capsular proteinV (LcrV) antigen

The mechanism involves the use of the Bacillus anthracis Protective Antigen (PA) to form a translocon pore in host cell membranes, allowing the N-terminal domain of Lethal Factor (LFn) fused with Yersinia pestis antigens (F1 and V) to enter the cytosol. These antigens are then degraded by the proteasome and presented on MHC Class I molecules to CD8+ T cells, while also being processed through the endocytic pathway for MHC Class II presentation to CD4+ T cells, thereby inducing a comprehensive humoral and cellular immune response (Kushner et al., 2003; Williamson et al., 2005).