Avaliação do potencial vacinal de nanopartículas de albumina sérica bovina conjugadas a antígenos totais de Pseudomonas aeruginosa em modelo de infecção pela Cepa Virulenta de P. aeruginosa

Abstract

Pseudomonas aeruginosa is an opportunistic pathogen that causes severe infections in immunocompromised individuals and in patients with cystic fibrosis. Vaccine candidates to prevent infections caused by P. aeruginosa have already been tested, but no vaccine against this pathogen is available on the market. Biodegradable polymeric nanoparticles may have adjuvant activity. Therefore, they are promising candidates for the production of vaccines if associated to antigens. The objective of this study was to evaluate the potential of bovine serum albumin (NPs-BSA) associated with total P. aeruginosa ATCC 27853 antigens in inducing protection against the virulent P. aeruginosa PA14 strain in murine model of nasal infection. NPs-BSA associated with the total P. aeruginosa ATCC 27853 antigens and empty nanoparticles (NPs), were used for the uptake analysis and in cytotoxity assay, employing RAW 264.7 and BHK-21 cells. For the immunogenicity analysis of NPs, Swiss mice were immunized with NPs associated with total P. aeruginosa antigens (NPPa) or empty NPs. As positive and negative control, groups of animals were immunized with total antigens of P. aeruginosa ATCC 27853 and phosphate buffered saline, respectively. The production of anti-P. aeruginosa and anti-BSA antibodies was evaluated by ELISA. Immunized mice were infected via nasal route using P. aeruginosa PA14 strain. The survival after 48 hours was evaluated and the lungs from animals were processed for quantification of bacterial load, cytokine expression and also for histopathological analysis. It was seen that the animals immunized with NPPa produced anti-P. aeruginosa and anti-BSA IgG antibodies. After infection with P. aeruginosa PA14, it was observed that the animals immunized with NPPa had the highest percentage of survival, the lowest bacterial lung load, a controlled production of cytokines and few histopathological changes. These results indicate that NPPa immunizations protected the mice from infection, contributing for the elimination of the bacteria from the lungs, which consequently reflected the survival of the animals.