Highly Expression and Purification of an Antigenic Region (D259-R462) of Adenylate Guanylate Cyclase Protein, Applicable for ELISA Test

HIGHLIGHTS

This is first study to present AGC protein as a candidate antigen in ELISA.

High yield 514.2 mg purity of recombinant protein.

Urea purification method is a simple and low-cost with high efficiency technique which has been used in this research.

rAcB demonstrating that might be useful for evaluation of antibody level in vaccinated animal.

Abstract

Leptospirosis is a wide spread bacterial zoonosis that is common worldwide. The disease symptoms are mild or acute. Leptospira has pathogenic and non-pathogenic species; it has a lot of surface antigens. Adenylate Guanylate Cyclase (AGC) is a membrane protein that is found only in pathogenic species. In this study, the complete coding sequences of AGC protein of 242 pathogen serovars were investigated by bioinformatics tools. A Pattern was selected as a target sequence based on high prevalence pathogenic serovars in Iran Antigen sites; moreover, B-cell and T-cell epitopes were predicted by IEDB web server. An antigen site amino acid (D259-R462) in complete coding sequence of AGC protein was selected. This nucleotide related sequence was cloned into the pET32a+ expression vector. Expression of recombinant protein was optimized in E. coli strain Bl21-DE3 by 0.2mM IPTG after 16-hour incubation at 37 ͦ C and confirmed by 10% SDS-PAGE and western blotting. Antigenic peptide D259-R462 was highly expressed as Trx tag fusion protein. Recombinant peptide (rAcB) was purified by 6M urea from inclusion body with high extent yield 514.2 mg per 1000ml culture of E. coli. 20µg rAcB protein with montanide adjuvant was injected subcutaneously in BALB/c mice. Results showed that the recombinant peptide D259-R462 was produced significant antibody compared to adjuvant and PBS groups. The induced antibody in sera of immunized animal with Leptospira vaccine was detected by 250 ng of rAcB coated in ELISA microplate. This study demonstrated that antigenic region (D259-R462) of AGC protein might be useful for evaluation of antibody level in vaccinated animal.

Keywords:
AGC; Leptospirosis; Recombinant protein