Development of oral-DNA-based vaccine against Clostridium perfringens using Lactobacillus expressing genetically modified beta toxin

Enteritis in bovine is resulting from Clostridium perfringens and may lead to death in calves. Beta toxin has been recognized as the main toxin involves in the pathogenesis. The study aims to induce mucosal immunity and protect calves against necrotic enteritis caused by Clostridium perfringens. Vaccine against C. perfringens was designed by deletion of signal peptides from beta toxin of C. perfringens. C terminal, (CPB-C 143-311) was selected as vaccine candidate with 170 amino acids. Modified toxin was tested about its antigenicity, toxicity, physiochemical and immunological properties. Also, docking of the modified protein with the immune receptor was determined using Insilco approach. The results of the immune informatics analysis show that the modified toxin is antigenic, non-toxic, non-allergic and stable. The modified protein was synthesized, cloned in pUC expression plasmid and transformed in to E. coli pet 21 strain. The recombinant plasmid was then transformed in our lab in to clinically isolated Lactobacillus strain. In vivo experiment was performed, 3 groups of mice (V1, V2 and T) were orally immunized with bacterial suspension of both E. coli, Lactobacillus, and PBS consequently. The immunized mice showed normal behavior and activity. Also, there is no any anatomical lesions after 14 days of the experiment which indicates safety of the modified toxin. Furthermore, Oral administration of both bacterial suspensions was able to induce the immune response in the mice. This study suggests that the modified beta protein may play a protective role against C. perfringens infection in mice.