Porin A (PorA) (PorA)

Porin A (PorA) is a major outer membrane protein of Neisseria meningitidis, particularly prominent in serogroup B strains where it serves as a critical vaccine antigen. Functionally, it acts as a class 1 outer membrane porin, forming a trimeric beta-barrel structure that facilitates the selective transport of cations and small hydrophilic molecules across the bacterial cell wall (UniProt: P05430). In the context of human disease, PorA is a primary target for the host immune system, as antibodies directed against its surface-exposed loops can trigger complement-mediated killing of the bacteria (PubMed: 11553241). This immunogenicity has led to its inclusion in several outer membrane vesicle (OMV) vaccines, such as Bexsero and MeNZB, designed to combat meningococcal meningitis and septicaemia (NCBI: NBK538214). However, the high rate of antigenic variation in the PorA variable regions (VR1 and VR2) poses a significant challenge for broad-spectrum vaccine development, often necessitating the use of multiple PorA variants or the inclusion of more conserved protein antigens (PubMed: 12655005). Consequently, PorA-based interventions are highly effective against specific strains but require ongoing surveillance of circulating meningococcal genotypes to ensure continued efficacy.

Other names

Class 1 outer membrane proteinPorin AMajor outer membrane protein PorAOMV PorAPorA protein

Acts as a vaccine antigen that induces the production of strain-specific bactericidal antibodies, which mediate complement-dependent killing of Neisseria meningitidis.