ACTA VETERINARIA ET ZOOTECHNICA SINICA ›› 2018, Vol. 49 ›› Issue (8): 1727-1734.doi: 10.11843/j.issn.0366-6964.2018.08.018

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Evaluation of Protective Efficacy of Recombinant Clostridium septicum α Toxin in Rabbits

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

  1. China Institute of Veterinary Drug Control, Beijing 100081, China
  • Received:2018-01-17 Online:2018-08-23 Published:2018-08-23

Abstract:

This study was conducted to obtain the recombinant Clostridium septicum α toxin and to evaluate its virulence and immunogenicity. Based on the known sequence, Gcsa, α toxin gene of C. septicum, was optimized and synthesized. Then, Gcsa was cloned into prokaryotic expression vector pET-30a (+) for expression and purification. Reactivity of the purified protein (rCSA) with antiserum of C. septicum was detected by Western blot. Meanwhile, Canine Kidney (MDCK) cell and mice were used to detect the virulence of rCSA. According to the method prescribed in Chinese Veterinary Pharmacopoeia (2015), four rabbits were immunized with rCSA emulsified with oil adjuvant of ISA 201 to prepare antiserum and detect the neutralizing titer. The results showed that rCSA was expressed at a high level as soluble form with a ratio about 50% by gray scale scanning, and it could react with the antiserum of C. septicum. For MDCK cell,the concentration of rCSA to induce apparent cytopathic effect (CPE) was found to be 0.15 ng·mL-1. At the same time, the Minimum Lethal Dose (MLD) of rCSA to ICR mice has been calculated as 1.5×106ng·kg-1. After the first immunization, sera from rabbits immunized with rCSA could neutralize 100-130 mice MLD C. septicum toxin per milliliter, and 360-480 mice MLD after twice immunization. Moreover, rabbits in rCSA immunized group fully survived from the challenge of C. septicum toxin at the dose of 1 rabbit MLD, whereas all of the rabbits died (4/4) in the control groups. These data suggest that rCSA has good immunogenicity, and can be used as a potential vaccine candidate for genetic engineering subunit vaccine of C. septicum.

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