BACTERIUM-LIKE PARTICLES DERIVED FROM THE RESPIRATORY COMMENSAL BACTERIA CORYNEBACTERIUM PSEUDODIPHTHERITICUM 090104 AS A PROMISING MUCOSAL ADJUVANT

RAMIRO ORTIZ MOYANO; FERNANDA RAYA-TONETTI; JACINTO SACUR; MIKADO TOMOKIYO; VYACHESLAV MELNIKOV; SUSANA ALVAREZ; HARUKI KITAZAWA; MARÍA GUADALUPE VIZOSO-PINTO; JULIO VILLENA

Congreso; REUNIÓN DE SOCIEDADES DE BIOCIENCIAS 2021 - LXIX REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA (SAI); 2022

Corynebacterium pseudodiphtheriticum is a Gram-positive bacterium that is part of the nasopharyngeal microbiota. This bacterium was shown to prevent the colonization of the respiratory mucosa by pathogenic bacteria including Streptococcus pneumoniae (Sp). We recently demonstrated that C. pseudodiphtheriticum 090104 (Cp), when nasally administered to mice; differentially modulated the respiratory immune responses triggered by TLR2 and improved the resistance to pneumococcal pneumonia. We also reported that bacterium-like particles derived from Cp (BPCp) had the ability to modulate the innate respiratory immunity. These results allowed us to hypothesize that Cp or BPCp could be used as mucosal adjuvants to enhance the respiratory adaptive immunity. In this work, infant Swiss-albino mice were nasally immunized with 6.25 pg of Pneumovax23® vaccine (PV), PV plus Cp (108 CFU) or PV plus BPCp at days 0, 14 and 28. Seven days after the last immunization samples of bronco-alveolar lavages (BAL) and serum were collected for specific antibodies determinations. In addition, immunized mice were challenged with Sp serotypes 6B or 19F (106 CFU) and the resistance to the infection was evaluated 2 days after the challenge. Mice in the PV+Cp and PV+BPCp groups had significantly higher levels of BAL anti-Sp IgG and IgA (p