Recombinant unpurified rETX H106P / CTB-rETX Y196E protects rabbits against Clostridium perfringens epsilon toxin

• Published in: Journal of veterinary medical science Vol. 83; no. 3; p. 441
• Main Authors: Peng, Xiaobing, Li, Xuni, Peng, Guorui, Feng, Lifang, Jiang, Yuwen, Luo, Yufeng
• Format: Journal Article
• Language: English
• Published: Japan 03.04.2021
• Subjects: Animals; Cholera Toxin; Clostridium perfringens - genetics; Enterotoxemia; Escherichia coli; Mice; Rabbits; Recombinant Proteins - genetics; bicistronic design system; epsilon toxin; recombinant vaccine; Clostridium perfringens
• ISSN: 1347-7439

Epsilon toxin (ETX), produced by Clostridium perfringens types B and D, has been touted as a potential biological weapon and is known to induce fatal enterotoxemia in a variety of livestock animals. For the efficient production of recombinant proteins with the objective of investigating the effects of different recombinant vaccines against ETX, a bicistronic design (BCD) expression system including the ETX coding sequence with mutation of amino acid 106 from Histidine to Proline (ETX ) in the first cistron, followed by Cholera Toxin B (CTB) linked with the ETX coding sequence with mutation of amino acid 196 from Tyrosine to Glutamic acid (ETX ) in the second cistron, was generated under the control of a single promoter. Rabbits were immunized twice with five inactivated recombinant Escherichia coli (E. coli) vaccines containing 100 µg/ml of the recombinant mutant rETX /CTB-rETX proteins mixed with different adjuvants. Apart from rETX /CTB-rETX -IMS1313-vaccinated rabbits, the neutralizing antibody titers of rETX /CTB-rETX -vaccinated rabbits were higher after the initial immunization than those administered the ETX toxoid or current commercial vaccines. rETX /CTB-rETX mixed with ISA201 induced the highest neutralizing antibody titer of 120 after the first immunization, suggesting that 0.1 ml of pooled sera could neutralize 120× mouse LD (100% lethal dose) of ETX. Following the second vaccination, rETX /CTB-rETX mixed with ISA201 or GR208 produced the highest neutralizing titer of 800. Rabbits from all vaccinated groups were completely protected from a 2× rabbit LD of ETX challenge. These results show that these novel recombinant proteins can induce a strong immune response and represent potential targets for the development of a commercial vaccine against the C. perfringens epsilon toxin.