Understanding the contribution of antibodies, against meningococcal serogroup B pili, to the bactericidal activity of sera from individuals vaccinated with Bexsero. (360G-Wellcome-207255_Z_17_Z)

The Bexsero vaccine provides protective immunity against many strains of Nm B and is composed of an outer membrane vesicle (OMV) backbone which contains the PorA serosubtype P1.4 and three other Nesserial proteins. These include; neisserial adhesion A(NAdA), neisserial heparin binding antigen(NHBA) and factor H binding protein (fHbp). However, the contribution of antibodies against key antigens within the OMV to Nm killing is unknown. Therefore, we will attempt to elucidate if antibodies generated against pili contribute to Nm killing in individuals vaccinated with Bexsero by using their sera in bactericidal assays. We will initially characterize pili expression in 10 meningococcal isolates for which the Bexsero vaccine isn’t predicted to protect against. SM1 and immune dot blotting will ascertain if pili are expressed at the bacterial surface. The presence of antibodies against pili in sera from 3 individuals who have been vaccinated with Bexsero will be confirmed using Western blotting and Tricine SDS-PAGE. The production of three pili negative strains will then be done using the MAG-1 knockout construct and natural transformation assays will be carried out on HBHI agar. Bactericidal assays using 10% sera from individuals vaccinated with Bexsero will be done for three pili expressing and knockout pairs.