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

[摘要] 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 H106P ) 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 Y196E ) 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 H106P /CTB-rETX Y196E proteins mixed with different adjuvants. Apart from rETX H106P /CTB-rETX Y196E -IMS1313-vaccinated rabbits, the neutralizing antibody titers of rETX H106P /CTB-rETX Y196E -vaccinated rabbits were higher after the initial immunization than those administered the ETX toxoid or current commercial vaccines. rETX H106P /CTB-rETX Y196E 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 (100% lethal dose) of ETX. Following the second vaccination, rETX H106P /CTB-rETX Y196E 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 100 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.

[学科分类] 兽医学

[关键词] bicistronic design system;Clostridium perfringens;epsilon toxin;recombinant vaccine