Generation of a recombinant GST-Tau antigen for indirect ELISA in evaluating Alzheimer’s disease vaccines

Background Alzheimer’s disease is a progressive neurodegenerative disorder. Immunotherapy targeting Aβ and Tau proteins is a promising strategy, and accurate detection of anti-Aβ or anti-Tau antibodies is key to evaluating vaccine efficacy. Indirect ELISA is a sensitive method requiring high-quality coating antigens. Methodology A recombinant Tau antigen fused to glutathione S-transferase (GST) was designed as an ELISA coating antigen. The Tau gene was cloned into the pGEX-6p-1 vector and expressed in Escherichia coli BL21 cells. Protein expression was induced with 1 mmol/L isopropyl-β-D-thiogalactoside (IPTG), and the GST-Tau fusion protein was identified by Western blot using anti-Tau and anti-GST antibodies. The protein was solubilized with 3 mol/L urea and purified via glutathione affinity chromatography. Purity was confirmed by densitometry and the optimal coating concentration for ELISA was determined to be 2 μg/mL. Results A protocol was established to produce GST-Tau with adequate purity and yield for ELISA applications. The recombinant antigen retained immunogenic epitopes, recognized by anti-Tau antibodies. The standardized ELISA enabled sensitive detection of anti-Tau antibodies. Conclusions A robust method was developed to produce and optimize GST-Tau as a coating antigen for indirect ELISA. This approach facilitates reliable quantification of anti-Tau antibodies to evaluate Alzheimer’s vaccine candidates.