Detergent-extracted OMV vaccines. Panel A. Electron micrograph of outer membrane vesicles of N. meningitides. The scale bar is 100 nm and the vesicle diameter is about 50–200 nm (80nm on average). Panel B. Major outer membrane proteins (PorA, PorB, reduction modifiable protein (RmpM) and opacity protein A (OpcA)) as visualized by Coommassie-stained SDS PAGE. Lane 1, molecular mass standards; lane 2, strain NZ98/254; lane 3, strain H44/76. After immunization, the SBA–responses of infants and children are directly predominantly against PorA. Adapted from published data [23]. Reprinted from Vaccine, vol 27, Supplement 2, 2009, Holst J, Martin D, Arnold R, et al. Properties and clinical performance of vaccines containing outer membrane vesicles from Neisseria meningitidis, with permission from Elsevier.