Cloning and Codon-optimized Expression of Structural Protein Hypervariable Region of VP2 from Infectious Bursal Disease Virus

Abstract

Infectious bursal disease virus (IBDV) is the causative agent of Gumboro disease, an infectious disease of global economic importance in poultry. Structural protein VP2 of IBDV is the most frequently studied protein due to its significant roles in virus attachment, protective immunity, and serotype specificity. The objective of the present study was to improve the expression of hypervariable region of VP2 protein (hvVP2) in <em>Escherichia coli</em> (<em>E.coli</em>). The results showed that the hvVP2 was expressed in very low amount in <em>E.coli</em>. But, codon optimized hvVP2 protein showed significantly enhanced protein expression level. The coding sequence of hvVP2 was amplified and then identified by polymerase chain reaction (PCR) and sequencing. To achieve high-level expression of hvVP2 protein, we optimized hvVP2 gene base on <em>E. coli</em> preferred codons and synthesized the optimized gene. The synthetical gene was cloned into expression vector pET-26b and expressed in <em>E.coli</em> BL21 (DE3). After induction with Isopropyl-D-1-Thiogalactopyranoside (IPTG) and optimization the conditions of expression, the hvVP2 protein was relatively increased and identified by SDS-PAGE and Western blotting. Productive conformation can now be used for structure-based design purposes as well as structure-function relation of VP1 protein. It is suggested that the codon optimized hvVP2-His protein may be a useful option (but it is not enough) for developing diagnostic tests and immunization proposes.