Outer membrane protein OpcA (OpcA)

Outer membrane protein OpcA (OpcA) is a major integral membrane adhesin and invasin found in Neisseria meningitidis, the causative agent of meningococcal meningitis and sepsis [1, 5]. It is a 10-stranded beta-barrel protein with extracellular loops that mediate high-affinity binding to host cell receptors, including heparan sulfate proteoglycans (HSPGs) and serum vitronectin [5, 8]. By binding vitronectin, OpcA facilitates bacterial attachment to host integrins (specifically alpha-v beta-3), promoting the invasion of epithelial and endothelial cells [5, 10]. This interaction is particularly critical for the pathogen's ability to traverse the blood-brain barrier and enter the central nervous system [4, 10]. Due to its surface exposure and role in pathogenesis, OpcA has been extensively studied as a candidate for protein-based and outer membrane vesicle (OMV) vaccines [8]. However, its utility as a universal vaccine target is challenged by phase variation, where the bacterium can rapidly switch OpcA expression on or off to evade the host immune response [8]. Recent research has also explored using OpcA as a targeting ligand in bionic nanotherapeutic systems to deliver chemotherapeutic agents across the blood-brain barrier for treating glioblastoma [4].

Other names

OpcClass 5 proteinOpcA adhesinMeningococcal OpcA

Vaccination induces bactericidal antibodies that neutralize the protein's adhesive function and promote complement-mediated killing; in nanomedicine, OpcA acts as a targeting ligand to facilitate receptor-mediated transcytosis across the blood-brain barrier.