Porin A (PorA) protein in Neisseria meningitidis serogroup B outer membrane vesicles (PorA)

Porin A (PorA) is a major outer membrane protein of Neisseria meningitidis, functioning as a cation-selective channel that facilitates the transport of small hydrophilic molecules across the bacterial outer membrane (PubMed: 11053373). In Neisseria meningitidis serogroup B (MenB), the polysaccharide capsule is poorly immunogenic due to its structural similarity to human neural cell adhesion molecules, making surface proteins like PorA primary targets for vaccine development (PubMed: 24509231). PorA-containing outer membrane vesicles (OMVs) are used as vaccine antigens because they present the protein in its native trimeric conformation, which is essential for inducing protective bactericidal antibodies. These antibodies recognize variable regions (VR1 and VR2) on the surface-exposed loops of PorA, leading to complement-mediated killing of the pathogen (PubMed: 15106081). Because PorA is highly antigenically diverse among different MenB strains, OMV-based vaccines are often tailored to specific regional outbreaks or included in multicomponent vaccines like Bexsero to broaden coverage (EMA: Bexsero Summary of Product Characteristics).

Other names

Class 1 outer membrane proteinPorin AMenB OMV antigenMajor outer membrane protein PorA

Induction of host immune response to produce serum bactericidal antibodies (SBA) that trigger complement-mediated lysis of Neisseria meningitidis.