Nucleic acid and amino acid sequences of the Omp85 proteins of N. gonorrhoeaeand N. meningitidis, and fragments thereof are useful in vaccine compositions,therapeutic compositions and diagnostic compositions for use in theprevention, treatment and diagnosis of non-symptomatic gonococcal infection orsymptomatic disease and non-symptomatic meningococcal infection andsymptomatic disease. Antibodies are developed to these proteins and alsouseful in the compositions and methods described herein.