Adjuvant properties of Outer Membrane Vesicles derived from Bordetella pertussis

RUDI, ERIKA; CASTUMA CELINA; GAILLARD MARÍA EMILIA; DANIELA HOZBOR

Congreso; 15.31. LXVIII Reunión Anual de la Sociedad Argentina de Inmunología (SAI); 2020

SAI

Pertussis is a vaccine preventable respiratory disease which is currently considered a serious health problem. We have designed a novel pertussis vaccine candidate based on outer membrane vesicles derived from B. pertussis (OMVsBp) that is safe, highly immunogenic, and protective in mouse model. OMVsBp includes a wide range of immunogens and PAMPs. Since these PAMPs could have adjuvant properties by themselves we wonder which is the contribution of the OMVs' integrity on their adjuvant properties. To addresses this aspect, we perform comparative studies between intact OMVs (OMVi) and mechanically disrupted OMVs (OMVD). Both OMVs were isolated and treated with standardized protocols and formulated with Fim3, a poorly immunogenic protein that is not present in OMVs. Fim3 was expressed and purified from a recombinant Escherichia coli strain. An immunization scheme was performed in Balb/C mice consisting of two immunizations with 0,75 µg of OMVi or OMVD combined with Fim3 (10 µg). Non immunized mice and OMVi, OMVD, or Fim3 immunized mice were used as control. Postvaccination serum samples were obtained, and a-Fim3 antibody levels were evaluated by Immunoblot and ELISA. By performing these experiments, we detected that OMVi+Fim3 induces higher antibody response a-Fim3 than OMVD+Fim3 (OMVi+Fim3: 3257 ± 264,5 vs OMVD+Fim3: 236,05 ± 56,63). Moreover, OMVi+Fim3 induced higher levels of a-Fim3 antibodies in comparison with that detected in Fim3 immunized mice (Fim3: 53,43 ± 11,97). Consistent with the ELISA results, serum samples obtained from OMVi+Fim3 immunized mice shown the highest reactivity against Fim3 in Immunoblot. The results presented here point out the relevance of OMVsBp integrity for its adjuvant properties.