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

BARTEL, E.; SABATER, D. ; ZURITA, E. ; RUMBO, M. ; BRAVO, M.S.; HOZBOR, D.

Buenos Aires

Simposio; 11th International Bordetella Symposim; 2016

BackgroundIt has been suggested that the loss of expression of the vaccine antigen pertactin (PRN) might provide a selectiveadvantage for Bordetella pertussis survival in acellular (aP)-vaccinated population. A new aP vaccine containinghigher number of epitopes inducing a broader immune response, is expected to improve the controlagainst current circulating PRN deficient bacteria. We have previously designed a vaccine candidate based onouter membrane vesicles (TdapOMVs) which was safe and elicited protective responses in animal model. ObjectiveTo evaluate and characterize the TdapOMVs protective capacity against a PRN(-) isolate. Comparisons withcommercial aP (consisting in few epitopes) and also wP (whole cell, multiple epitopes) vaccines were performed. Materials and MethodsActive 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 opsonophagocytosisassays.ResultsIn contrast to the commercial aP vaccine, TdapOMVs induced adequate protection level against the infectionof PRN(-) (1000 times decrease in CFU/lung when compared to non-immunized mice). The decrease producedby aP vaccine was lower (25 times, p < 0,01). wP exhibited similar reduction levels than TdapOMVs. Clearanceof bacteria was mediated, partially, by TdapOMVs and wP vaccine induced antibodies, since sera from miceimmunized 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 neitherprotective nor opsonizing capacity towards this isolate. ConclusionThese results suggest that vaccines comprised of multiple epitopes as commercial wP and the novel OMVsbased-vaccine are more appropriate to address infections caused by isolates exhibiting altered expression ofvaccine antigens.