Efficacy of a Conjugate Vaccine Containing Polymannuronic Acid and Flagellin against Experimental Pseudomonas aeruginosa Lung Infection in Mice

Abstract

Vaccines that could effectively prevent Pseudomonas aeruginosa pulmonary infections in the settings of cystic fibrosis (CF) and nosocomial pneumonia could be exceedingly useful, but to date no effective immunotherapy targeting this pathogen has been successfully developed for routine use in humans. Evaluations using animals and limited human trials of vaccines and their associated immune effectors against different P. aeruginosa antigens have suggested that antibody to the conserved surface polysaccharide alginate, as well as the flagellar proteins, often give high levels of protection. However, alginate itself does not elicit protective antibody in humans, and flagellar vaccines containing the two predominant serotypes of this antigen may not provide sufficient coverage against variant flagellar types. To evaluate if combining these antigens in a conjugate vaccine would be potentially efficacious, we conjugated polymannuronic acid (PMA), containing the blocks of mannuronic acid conserved in all P. aeruginosa alginates, to type a flagellin (FLA) and evaluated immunogenicity, opsonic killing activity, and passive protective efficacy in mice. The PMA-FLA conjugate was highly immunogenic in mice and rabbits and elicited opsonic antibodies against mucoid but not nonmucoid P. aeruginosa, but nonetheless rabbit antibody to PMA-FLA showed evidence of protective efficacy against both types of this organism in a mouse lung infection model. Importantly, the PMA-FLA conjugate vaccine did not elicit antibodies that neutralized the Toll-like receptor 5 (TLR5)-activating activity of flagellin, an important part of innate immunity to flagellated microbial pathogens. Conjugation of PMA to FLA appears to be a promising path for developing a broadly protective vaccine against P. aeruginosa.

ISCOMATRIX: a novel adjuvant for use in prophylactic and therapeutic vaccines against infectious diseases

“…The TLR-5 agonist flagellin enhances the immunogenicity of poorly immunogenic antigens when chemically linked. Protective Ab responses were observed in mice vaccinated against Yersinia pestis, West Nile virus, vaccinia virus, influenza virus, Pseudomonas aeruginosa and parasites (Campodó nico et al, 2011;Mizel & Bates, 2010). Flagellin conjugated with haemagglutinin from H1N1 influenza virus has been shown to be safe and to induce seroprotection in the elderly (Taylor et al, 2011).…”

Synthesis, Characterization, and Immunological Properties of LPS-Based Vaccines Composed of O-Polysaccharides Conjugated with Recombinant Exoprotein A from <i>Pseudomonas aeruginosa</i>

“…However, some protections were observed using alginate-base conjugates in experimental animals [7] [8].…”

Conjugation of alginate to a synthetic peptide containing T- and B-cell epitopes as an induction for protective immunity against Pseudomonas aeruginosa

“…Alginate has been coupled to various carrier proteins such as exotoxin A, tetanus toxoid, keyhole limpet hemocyanin (KLH) and flagellin (Campodonico et al, 2011;Cryz et al, 1991;Kashef et al, 2006;Theilacker et al, 2003 proteins in general have many epitopes, some of which may suppress a main response (Peeters et al, 1991). Using peptide carriers could overcome such issues.…”

“…Previous studies have demonstrated the important role of alginate as a factor affecting virulence of P. aeruginosa infections (Branny et al, 2001;Gacesa and Russell, 1990;Mai et al, 1993;Pedersen et al, 1992;Pier et al, 1990;Stewart and Costerton, 2001). Many studies have demonstrated high titers of opsonic antibodies elicited in animals by conjugation of alginate to a carrier protein, and that the carbohydrate moiety would be a T-cell-dependent antigen (Campodonico et al, 2011;Cryz et al, 1991;Kashef et al, 2006;Theilacker et al, 2003). Generally, the response of antibody against polysaccharide (PS) antigens induces low titer IgM, results that fail to switch class to IgG, lack of antibody maturation and no immunologic memory (Humphrey et al, 1964;Weissman et al, 1976).…”