A Simple Method for High-Level Expression of HTLV-1 gp46-I(162-214) Peptide and Its Application for Screening

Abstract

Background: Gp46-I(162-214) is a linear peptide derived from human T-lymphotropic virus Type 1 (HTLV-1) gp46-I envelope protein. This protein is commonly used to detect HTLV-1 antibodies during enzyme-linked immunosorbent assay (ELISA) or Western blotting. Objectives: This study reported a simple and efficient method for large-scale preparation of this peptide, which is employed for diagnostic purposes. Methods: This study was a descriptive research. The DNA encoding gp46-I(162-214) was optimized according to E. coli codon usage. It was then synthesized and sub cloned into a pGS21a vector. This vector added a His-GST tag to the N-terminus of the protein. The pGS21a-gp46-I(162-214) was transformed into the chemically competent E. coli BL21 cells and His-GST-gp46-I(162-214) was expressed as an insoluble form. After the isolation of inclusion bodies, His-GST-gp46-I(162-214) was purified and on-column refolding was performed using Nickel-nitrilotriacetic acid (Ni-NTA) affinity chromatography. ELISA was then applied to assess the antigenicity of the His-GST-gp46-I(162-214) protein using sera specimens from HTLV-1 infected patients. Results: The Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) results revealed that His-GST-gp46-I(162-214) protein accounted for 30% of the insoluble proteins. The results of ELISA highlighted concentration-dependent interactions between the refolded His-GST-gp46-I(162-214) and HTLV-1antibodies. Furthermore, the refolded His-GST-gp46-I(162-214) and synthetic gp46-I(162-214) had similar reactivity. Conclusions: Combination of key strategies including codon optimization, expression as inclusion body, and on-column refolding provide an efficient and facile platform for producing gp46-I(162-214) peptide.