PorA protein (Major outer membrane protein, formerly class 1 protein) from Neisseria meningitidis (PorA)

The PorA protein is a major surface-exposed outer membrane porin in *Neisseria meningitidis* serogroup B. It forms cation-selective channels responsible for nutrient uptake and is a key target of bactericidal antibodies elicited by infection or vaccination. PorA is highly variable, with different subtypes defined by sequence differences in surface-exposed loop regions, leading to strain-specific immune responses. It is included in OMV-based vaccines, but antigenic and phase variation restricting surface expression complicate broad protection. OMV vesicles themselves contain many additional proteins, but PorA remains the principal vaccine antigen for group B disease.

Other names

Class 1 outer membrane proteinmeningococcal PorANeisseria meningitidis PorAmajor outer membrane protein P1

Induction of protective antibody response targeting PorA, leading to opsonophagocytosis and complement-mediated bacterial killing