Outer surface protein A (Borrelia burgdorferi) (OspA)

Outer surface protein A (OspA) is an abundant, immunogenic lipoprotein found on the outer membrane of Borrelia burgdorferi, the causative agent of Lyme disease[1][2][5]. OspA is primarily expressed during colonization of the tick vector’s midgut and is downregulated in the mammalian host. It serves important roles in anchoring Borrelia to the tick gut by binding tick midgut receptors and is implicated in shielding conserved bacterial surface antigens from host antibodies during blood meals[7]. OspA is a monomeric protein of approximately 28 kDa, extremely resistant to trypsin and structurally unique, with a repetitive anti-parallel β-sheet topology and variable surface-exposed domains[1][2][3]. Recombinant OspA has been developed as a vaccine antigen, eliciting protective immune responses by promoting the production of OspA-specific antibodies that neutralize Borrelia in the tick, blocking transmission to humans and other mammals[5][7]. Antigenic variation among OspA from different Borrelia species/strains poses challenges for broad vaccine design[5]. OspA’s immunogenicity also makes it a valuable diagnostic and research tool in Lyme disease.

Other names

OspAMajor outer surface protein ALyme disease antigen OspA

Vaccines/antibodies targeting OspA induce an immune response that neutralizes Borrelia burgdorferi, preventing infection or aiding in pathogen clearance[1][5][7]