CONICET | Buscador de Institutos y Recursos Humanos

S. pneumoniae (Sp) is an important respiratory pathogen because it causes high morbidity and mortality rates around the world. New strategies for the fight against pneumococci are necessary and some serotype independent pneumococcal proteins are good candidates for mucosal vaccines. Adjuvants must administer pneumococcal proteins to induce a good mucosal immune response. Objective: To assess the protective immune response induced by nasal vaccination with protective pneumococcal protein A (PppA) associated to Lactobacillus casei (Lc) as adjuvant. Swiss albino mice were nasally immunized with PppA(10ug) +Lc (109 cells/d/mice) using a protocol that included 3 successive doses with a 14-day interval between them. Groups that received Lc, PppA and PBS were used as controls. Serum (S), bronchoalveolar and nasal lavages (BAL, NAL) were collected at different days (0, 28, 42, 58 and 73). Assays: 1) IgA and IgG anti-PppA antibodies (a-PppA) in S, BAL and NAL; 2) Cytokines: IL-4, IL-10; IL-17, INF-gamma and IL-2 were evaluated in S, BAL and NA; 3) Survival Assay: Survival of mice after intraperitoneal challenge (IP) with Sp was evaluated until d 21. Results: PppA+Lc induced high specific IgA and IgG antibody levels in both mucosal and systemic compartments compared with PppA (42d: IgA=BAL: p<0.01; NAL: p<0.05, S: p<0.05). Also, PppA+Lc induced a higher stimulation of the Th populations (Th1, Th2 and Th17) than the PppA and Lc groups, in mucosal compartment. In addition, PppA+Lc significantly increased survival compared to the control (p<0.05, Cox-Mantel test). The specific immune response induced by immunization was maintained in time so immune memory was stimulated. Association of a probiotic and a pneumococcal protein as nasal vaccines would be a good and safe strategy to prevent pneumococcal infection.