Towards a nasal vaccine against meningococcal disease, and prospects for its use as a mucosal adjuvant.

A Norwegian outer membrane vesicle (OMV) vaccine against group B meningococcal disease proved to be strongly immunogenic when administered intranasally in mice. The OMV preparation, made from Neisseria meningitidis and intended for parenteral use, was therefore given without adjuvant to human volunteers (n = 12) in the form of nose drops or nasal spray. Such immunizations, which were carried out at weekly intervals during a three-week period, were able to induce systemic antibodies with bactericidal activity in more than half of the individuals. In addition, all vaccinees developed marked increases in OMV-specific IgA antibodies in nasal secretions. The potential of the OMV particles as carriers for other less immunogenic antigens were elucidated in mice with use of whole inactivated influenza virus. Even though influenza virus alone did induce some systemic and salivary antibody responses after being administered intranasally, these responses were greatly augmented when the virus was presented together with OMVs. Thus, it is possible that a nasal OMV vaccine may induce protection against invasive meningococcal disease, and also that it might be used as a vehicle for nasal vaccines against other diseases.