Outer membrane vesicles as acellular vaccine against pertussis.

In this study the development and evaluation of outer membrane vesicles (OMVs) obtained from Bordetella pertussis as vaccines against pertussis disease is described. SDS-PAGE, immunoblot techniques and gel electrophoresis associated to tandem mass spectrometry were used to describe the composition of the OMVs obtained from B. pertussis Tohama CIP 8132 strain. These techniques revealed the presence of the main well-known pertussis surface immunogens in the OMVs such as pertactin, adenylate cyclase-haemolysin, pertussis toxin, as well as the lipo-oligosaccharide (LOS). A total of 43 proteins were identified by mass spectrometry. Some of them were predicted to have outer membrane or periplasmic location and the others with cytoplasmic or unknown location. The characterized pertussis OMVs were used in murine B. pertussis intranasal (i.n.) challenge model to examine their protective capacity when delivered by different routes. Killed detoxified whole-cell B. pertussis bacteria were used as reference. For intraperitoneal (i.p.) immunization, aluminum hydroxide was used as adjuvant. Since i.n. treatment with OMVs as well as killed whole-cell bacteria enhanced markers of innate immune response such as TNFalpha, IL-6 and CCL20, i.n. immunizations were performed with no adjuvant added. Immunized BALB/c mice were intranasally challenged with sublethal doses of B. pertussis. Significant differences between immunized animals and the PBS treated group were observed (p<0.001). Adequate elimination rates (p<0.005) were observed in mice immunized either with OMV or whole-cell bacteria. Comparable results were obtained with both types of immunization route. In view to their capacity to induce airways innate and protective immunity in the mouse model, OMVs obtained from B pertussis are candidates to be used to protect against pertussis.