ACTA VETERINARIA ET ZOOTECHNICA SINICA ›› 2018, Vol. 49 ›› Issue (4): 777-785.doi: 10.11843/j.issn.0366-6964.2018.04.015

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Evaluation of Protective Efficacy of Recombinant Mutant of Clostridium perfringens ε Toxin

DU Ji-ge, ZHU Zhen, XUE Qi, LI Qi-hong, YIN Chun-sheng, PENG Xiao-bing, YAO Wen-sheng, KANG Kai, CHEN Xiao-yun*   

  1. China Institute of Veterinary Drug Control, Beijing 100081, China
  • Received:2017-09-07 Online:2018-04-23 Published:2018-04-23

Abstract:

This experiment was conducted to obtain recombinant mutant of Clostridium perfringens ε toxin and subsequently evaluate the virulence and immunogenicity of the recombinant toxin. The ε toxin gene of C. perfringens type D strain using optimized codons was synthesized based on the sequence reported. At the same time, three amino acid mutations:Y30 and Y196 substituted with alanine, H106 substituted with proline, were introduced into this sequence synthesized. Then,this ε toxin gene was cloned into prokaryotic expression vector pET3a- (+) to construct a recombinant E. coli, followed by induction with IPTG to yield the recombinant protein,following with purification. The reactivity of the purified protein with antiserum of C. perfringens type D was determined by Western blot and the mouse was used to evaluate the virulence of purified protein. The rabbit antiserum against the recombinant proteins was prepared and the neutralizing titer was measured according to the method prescribed in Chinese Veterinary Pharmacopoeia (2015). The results showed that recombinant protein was expressed at a high level in a soluble form with a ratio of about 40% by gray scale scanning, And the protein could react with the antiserum of C. perfringens type D. The protein with the injection volume of 6.25×106 ng·kg-1 still shows no virulence to mouse. The titer of rabbit antiserum against Clostridium perfringens type D could reach 50-60 and 400-450 Minimum Lethal Dose (MLD) after the first and second immunization and respectively.After challenge with 1MLD of C. perfringens type D toxin, all the rabbits immunized with recombinant protein were protected. The results suggest that the recombinant mutant of C. perfringens ε toxin without virulence retains the good immunogenic antigen, which provides important experimental data for the development of novel C. perfringens vaccine.

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