Scand J Immunol. 2014 Apr;79(4):244-50. doi: 10.1111/sji.12155.
This study aimed to evaluate the efficacy and safety of an oral DNA vaccine against somatostatin (SS) (pGS/2SS-asd, encoding two copies of somatostatin genes) mediated by attenuated Salmonella choleraesuis C500 without antibiotic resistance gene on piglets growth. A total of 50 piglets were uniformly divided into five groups. The animals in the first three groups were orally given vaccine in dose of either 5 9 1010, 5 9 109 or 5 9 108 colony-forming units (CFU).The remaining two groups were orally administered with either bacteria C500(containing pVAX-asd plasmid without somatostatin gene) or phosphate buffered saline (PBS) as controls. The results indicated that the vaccine induced SS-specific antibodies in a dose-dependent pattern. Compared with the PBS control, animals in the high-dose group showed lower SS levels and higher growth hormone (GH) levels in sera. Average daily gain of animals in the high dose group was increased by 32.88% and 26.46% during 4 and 8 weeks,respectively. Anti-SS antibodies were positively correlated with either GH levels or average daily gain at week 8 after primary immunization (P < 0.05). Faecal,soil and water samples originating from immunized piglets and surrounding environment were collected. The target gene (the fusion gene GS/2SS) of C500(pGS/2SS-asd) was not detected by PCR amplification in these samples,indicating that the surrounding environment was not contaminated by residual recombinant bacteria. In conclusion, the vaccine without antibiotic resistance gene is attributable to improve growth performance of piglets through an influence on GH secretion. Moreover, the immunization did not contaminate the surrounding environment of animals.
本研究旨在评估口服减毒霍乱沙门氏菌 C500 传递的无抗生素抗性基因的生长抑素（SS）（pGS/2SS-asd，编码两个 SS 基因副本）的口服 DNA 疫苗对仔猪生长的疗效和安全性。将 50 头仔猪均匀分为五组。前三组动物以 5 9 1010、5 9 109 或 5 9 108 个集落形成单位（CFU）的剂量口服给予疫苗。其余两组动物分别口服给予 C500 菌（含有不含 SS 基因的 pVAX-asd 质粒）或磷酸盐缓冲盐水（PBS）作为对照。结果表明，疫苗诱导了剂量依赖性的 SS 特异性抗体。与 PBS 对照组相比，高剂量组动物血清中的 SS 水平较低，生长激素（GH）水平较高。高剂量组动物在第 4 周和第 8 周的平均日增重分别增加了 32.88%和 26.46%。初次免疫后第 8 周，抗 SS 抗体与 GH 水平或平均日增重呈正相关（P < 0.05）。从免疫仔猪及其周围环境中采集粪便、土壤和水样。这些样品中未通过 PCR 扩增检测到 C500（pGS/2SS-asd）的靶基因（GS/2SS 融合基因），表明周围环境未被残留重组菌污染。总之，该无抗生素抗性基因疫苗通过影响 GH 分泌来提高仔猪的生长性能，且免疫不会污染动物的周围环境。
