Production of soluble Borrelia afzelii outer surface protein A in Escherichia coli expression system

The Borrelia burgdorferi sensu lato complex includes species that pose a growing global health challenge, with increasing reports of severe cases and fatalies, especially those linked to Borrelia afzelii in parts of Asia.Outer surface protein A (OspA), a key lipoprotein essenal for ck midgut colonizaon, serves as an important target for both diagnosc tools and vaccine development.This study focused on enhancing the producon of soluble recombinant OspA from B. afzelii using an Escherichia coli expression system.The OspA gene from B. afzelii strain BO23 was cloned into the pET-28a(+) vector, incorporang an N-terminal His-tag, and expressed in E. coli BL21 Star (DE3).Expression was opmized by inducon with 0.5 mM IPTG for five hours at 37C in LB broth supplemented with 0.2% glucose, resulng in a yield of 5.8 mg/L of soluble OspA.Affinity chromatography achieved a purity level exceeding 90%, and the protein's immunoreacvity was confirmed using Western blot and Dot blot assays with a commercial monoclonal anbody against OspA.