Serum albumin nanoparticles vaccine provides protection against a lethal Pseudomonas aeruginosa challenge

Pseudomonas aeruginosa is an opportunistic pathogen that causes severe infections in immunocompromised individuals and in patients with cystic fibrosis. A range of vaccines to prevent infections caused by P. aeruginosa has already been tested, yet no vaccine against this pathogen is currently available. The goal of this study was to evaluate the potential of bovine serum albumin nanoparticles (BSA-NPs) associated with total P. aeruginosa ATCC 27853 antigens in inducing protection against the infection with virulent P. aeruginosa PA14 strain in murine model of nasal infection. Swiss mice were immunized with BSA-NPs associated with total P. aeruginosa antigens (NPPa) or empty NPs (NPe). As positive and negative control, groups of animals were immunized with total antigens of P. aeruginosa ATCC 27853 and phosphate buffered saline, respectively. Immunized mice were infected via nasal route using P. aeruginosa PA14 strain. The survival after 48 h was evaluated and the lungs from animals were processed for quantification of bacterial load, cytokine expression and histopathological analysis. After infection with P. aeruginosa PA14, animals immunized with NPPa had the highest survival rate, the lowest bacterial lung load, a controlled production of cytokines and few histopathological changes. These results indicate that NPPa immunization protected mice from infection, contributing for the elimination of the bacteria from the lungs, which consequently reflected the survival of the animals. Therefore, this vaccine was able to induce a functional response in an animal model of lethal infection and thereby is a promising platform for P. aeruginosa vaccines.