StxB fusion strategy for immunogenic enhancement: Recombinant expression of AcAMP antimicrobial peptide

Abstract

Background and objectives

Polyclonal antibodies are essential for identifying compounds like peptides. However, many peptides exhibit low immunogenicity, resulting in reduced antibody yields. To address this, fusing peptides with immunogenic fusion proteins has been proposed. This study aimed to enhance the immunogenicity of the AcAMP peptide by fusing it with StxB as a fusion protein, producing the recombinant construct in Escherichia coli, and comparing its antibody titration to recombinant AcAMP in mice.

Methods

The acamp gene, containing BamHI and SalI restriction sites, was amplified from the pUC57 plasmid via PCR and cloned into the pET28a (+)-StxB expression vector. The pET28a (+)-AcAMP construct was prepared as previously described. Both constructs were expressed in E. coli BL21 (DE3) cells, induced with IPTG, and purified using nickel affinity chromatography. Recombinant proteins were confirmed by SDS-PAGE and Western blotting. Mice were immunized with purified proteins, and serum IgG titration was assessed using indirect ELISA.

Results

PCR amplification and enzymatic digestion verified the successful construction of the pET28a (+)-StxB-acamp vector. SDS-PAGE and Western blotting identified recombinant AcAMP and AcAMP-StxB proteins at 9 and 17 kDa, respectively. ELISA revealed significantly higher antibody titers for the recombinant AcAMP-StxB protein compared to recombinant AcAMP.

Conclusion

Fusing the AcAMP peptide with the StxB protein enhanced immunogenicity and increased antibody production. This approach may improve expression conditions and immunogenicity for peptides of this family, advancing their use in identification studies.