ACELLULAR PERTUSSIS VACCINE CANDIDATE BASED ON OUTER MEMBRANE VESICLES (OMVS) PROTECTS AGAINST BORDETELLA PERTUSSIS PERTACTIN DEFICIENT STRAINS

BARTEL, ERIKA; ZURITA, MARIA EUGENIA; BRAVO, MARÍA SOL; SABATER, DAVID; RUMBO, MARTIN; HOZBOR, DANIELA

Simposio; 11th Simposion de Bordetella; 2016

Background: It has been suggested that the loss of expression of the vaccine antigen pertactin (PRN) might provide a selective advantage for Bordetella pertussis survival in acellular (aP)-vaccinated population. A new aP vaccine containing higher number of epitopes inducing a broader immune response, is expected to improve the control against current circulating PRN deficient bacteria. We have previously designed a vaccine candidate based on outer membrane vesicles (TdapOMVs) which was safe and elicited protective responses in animal model. Objective: To evaluate and characterize the TdapOMVs protective capacity against a PRN(-) isolate. Comparisons with commercial aP (consisting in few epitopes) and also wP (whole cell, multiple epitopes) vaccines were performed. Materials and Methods: Active protective capacity of the studied vaccines was evaluated using the mice intranasal challenge model. Functional role of the induced humoral responses was assessed in vivo by transfer assays and in vitro by opsonophagocytosis assays. Results: In contrast to the commercial aP vaccine, TdapOMVs induced adequate protection level against the infection of PRN(-) (1000 times decrease in CFU/lung when compared to non-immunized mice). The decrease produced by aP vaccine was lower (25 times, p < 0,01). wP exhibited similar reduction levels than TdapOMVs. Clearance of bacteria was mediated, partially, by TdapOMVs and wP vaccine induced antibodies, since sera from mice immunized with these vaccines induced protection against the PRN(-) isolate when transferred to naive mice (p < 0,05). Moreover, these sera had opsonizing capacity over PRN(-). aP immune sera did not exhibit neither protective nor opsonizing capacity towards this isolate. Conclusion: These results suggest that vaccines comprised of multiple epitopes as commercial wP and the novel OMVs based-vaccine are more appropriate to address infections caused by isolates exhibiting altered expression of vaccine antigens