Bacterium-like Particles fromCorynebacterium pseudodiphtheriticum as Mucosal Adjuvant for the Development of Pneumococcal Vaccines

ORTIZ MOYANO, R.; RAYA TONETTI, M. F.; ELEAN, M.; IMAMURA, Y.; FUKUYAMA, KOHTARO; SUDA, Y.; MELNIKOV, VYACHESLAV; SUVOROV, A.; VIZOSO PINTO, M. G.; KITAZAWA, H.; VILLENA, J.

Vaccines

MDPI

Lugar: Basel; Año: 2024

2076-393X

Previously, it was shown that intranasally (i.n.) administered Corynebacterium pseudodiphtheriticum090104 (Cp) or CP-derived bacterium-like particles (BLPs) improve the immunogenicity ofthe pneumococcal conjugate vaccine (PCV). This work aimed to deepen the characterization of theadjuvant properties of Cp and CP-derived BLPs for their use in the development of pneumococcalvaccines. The ability of Cp and CP-derived BLPs to improve both the humoral and cellular specificimmune responses induced by i.n. administered polysaccharide-based commercial pneumococcalvaccine (Pneumovax 23®) and the chimeric recombinant PSPF (PsaA-Spr1875-PspA-FliC) proteinwas evaluated, as well as the protection against Streptococcus pneumoniae infection in infant mice.Additionally, whether the immunization protocols, including Cp and CP-derived BLPs, togetherwith the pneumococcal vaccines can enhance the resistance to secondary pneumococcal pneumoniainduced after inflammatory lung damage mediated by the activation of Toll-like receptor 3 (TLR3)was assessed. The results showed that both Cp and CP-derived BLPs increased the immunogenicityand protection induced by two pneumococcal vaccines administered through the nasal route. Ofnote, the nasal priming with the PSPF T-dependent antigen co-administered with Cp or CP-derivedBLPs efficiently stimulated humoral and cellular immunity and increased the resistance to primaryand secondary pneumococcal infections. The CP-derived BLPs presented a stronger effect than livebacteria. Given safety concerns associated with live bacterium administration, especially in high-riskpopulations, such as infants, the elderly, and immunocompromised patients, BLPs emerge as anattractive mucosal adjuvant to improve the host response to pneumococcal infections and to enhancethe vaccines already in the market or in development.