To measure the serum bactericidal antibody levels and cell mediated immune responses before and six weeks after each dose of meningococcal outer membrane vesicle vaccine given at 0,6 and 12 weeks to healthy UK adults.

Inclusion Criteria:

• Informed written consent given for three immunizations with MenBVac and five blood tests
• Between the ages of 18 and 55 years inclusive at recruitment

Exclusion Criteria:

• Previous history of bacteriologically confirmed meningococcal disease
• History of clinically significant allergic sensitivity to any vaccine received in the past
• Immunodeficiency
• Any other acute or chronic systemic illness or dependence or abuse of drugs or alcohol
• Language difficulties sufficient to preclude adequate comprehension of the study information
• Possibility of pregnancy
• Receipt of any other vaccine in the previous 4 weeks
• Receipt of any group B vaccine in the past
• Current participation in any other clinical trial
• Generalized acute systemic illness and/or temp >38C on day of vaccination deferral