Project Summary/Abstract Neisseria meningitidis (Nm) cause life-threatening bacterial meningitis and sepsis and N. gonorrhoeae (Ng) cause millions of sexually transmitted infections annually. Emerging multiple antibiotic resistance by Ng and recent increases in incidence have led to its designation as an urgent threat by the CDC. There are no licensed Nm vaccines in the US for <10 year olds, the population at greatest risk of disease and no licensed Ng vaccine. We have developed an Nm serogroup B (NmB) vaccine based on native outer membrane vesicles (NOMV) with genetically attenuated endotoxin activity and over- expressed mutant Factor H binding protein (FHbp) with reduced FH binding. In both mice and infant macaques, the vaccine elicited much higher human complement-mediated serum bactericidal antibody (SBA) responses than a licensed NmB vaccine. The vaccine, NOMV-FHbp, also elicited SBA against Ng in mice and in infant macaques. We used anti-NOMV-FHbp antibodies to identify Ng antigens that are highly conserved between Nm and Ng. Our hypothesis is that an NOMV vaccine with over produced mutant FHbps from subfamilies A and B and conserved Nm/Ng antigens will elicit antibodies that provide broad protection against disease by both pathogens in all age groups. In Aim 1, we will use an engineered promoter to over produce mutant FHbps from subfamilies A and B and two or more highly conserved Ng antigens that elicit protective antibodies (NmNg-NOMV vaccine). In Aim 2, we will test the ability of NmNg-NOMV to prevent colonization and invasion in immortalized and primary nasal and cervical cell culture models. In Aim 3, we will test the ability of optimized NmNg-NOMV vaccines to prevent colonization and symptoms of disease in transgenic mouse models of meningococcal nasal colonization and meningitis and in a female estradiol-treated Tg mouse model of gonococcal vaginal colonization. Preventing colonization and invasion is important for providing individual protection against disease and preventing transmission between individuals (i.e. “community immunity”). The overall goal is development of an NOMV vaccine platform for expression of conserved Neisseria antigens with native structures that can elicit broadly protective antibodies against both pathogens. Successful development of an NmNg-NOMV vaccine would have a significant public health impact world-wide.