Construction of a Eukaryotic Plasmid Encoding Bacillus anthracis Protective Antigen, a Candidate for DNA Vaccine

Background: DNA immunization with plasmid DNA encoding bacterial, viral, parasitic and tumor antigens has been reported to trigger protective immunity. Objective: To evaluate the use of a DNA immunization strategy for protection against anthrax, a plasmid was constructed. Methods: The partialsequence of protective antigen of Bacillus anthracis, amino acids 175-764, as a potent immunogenic target was selected. The DNA encoding this segment was utilized in the construction of pcDNA3.1+PA plasmid. After intramuscular injection of rats with pcDNA3.1+PA plasmid, the expression of PA was assessed by RT-PCR and immunohistochemistry at RNA and protein levels, respectively. We also evaluated the presence of anti-PA antibodies in sera of immunized mice with pcDNA3.1+PA construct using immunoblotting. Results: The integrity of pcDNA3.1+PA construct was confirmed with restriction analysis and sequencing. The expression of PA was detected at RNA and protein levels. The presence of anti-PA antibodies in immunized mice with pcDNA3.1+PA construct was also confirmed. Conclusion: Our results indicate that pcDNA3.1+PA eukaryotic expressing vector could express PA antigen, induce antibody response and may be used as a candidate for DNA vaccine against anthrax.