不同佐剂对大鲵嗜水气单胞菌灭活疫苗的免疫效果

为了探究添加蜂胶佐剂、弗氏佐剂和铝胶佐剂后对大鲵（Andrias davidianus）嗜水气单胞菌（Aeromonas hydrophila）灭活疫苗的免疫效果，取已制备好的大鲵嗜水气单胞菌灭活疫苗，分别加入3种佐剂，充分混匀后制备成含菌量为1×108 CFU/mL的佐剂疫苗，通过腹腔注射免疫健康大鲵(平均体长40 cm、平均体质量85 g），每尾1 mL，并设不加佐剂组和对照组；分别于免疫后第1、4、7、14、21、28、35天尾静脉采血，利用凝集反应检测血清抗体效价，于免疫后第35天进行攻毒感染试验。结果表明，与对照组相比，蜂胶佐剂组抗体效价于免疫后第1～14天呈上升趋势，第21天达最高，为1: 469.33，弗氏佐剂组于免疫后第1～28天呈上升趋势，第35天达到最大值，为1: 448.00，随后呈下降趋势；铝胶佐剂组抗体效价于免疫后第1～21天呈上升趋势，第28天达到最大值，为1: 362.67，不加佐剂组于免疫后第21天达最高，为1: 384.00，随后呈下降趋势，而对照组基本稳定在1:4.00。攻毒感染试验表明，蜂胶佐剂组、弗氏佐剂组、铝胶佐剂组和不加佐剂组的死亡率为10%、20%、25%和35%，相对免疫保护率分别为88.9%、77.8%、72.2%和61.1%，对照组大鲵死亡率为90%；3种佐剂疫苗均有较好的免疫保护效果，其中以蜂胶佐剂疫苗效果最佳。

Effect of Adjuvants on the Response of Andrias davidianus Immunized with Inactivated Aeromonas hydrophila Vaccine

Andrias davidianus (the Chinese giant salamander) is a unique and rare amphibian with important value for biodiversity, scientific research and medicine and is also considered a delicacy. However, in recent years, the occurrence of an infectious disease has seriously hampered the development of large-scale cultivation of A. davidianus, resulting in economic loss to farmers. Aeromonas hydrophila is the pathogenic bacteria responsible for severe ascitesosis in A. davidianus, a serious disease that can result in the death of the salamander on a large scale. The extensive use of antibacterial agents could lead to a drug resistance in Aeromonas hydrophila, so it is important to develop a safe and effective vaccine to prevent the disease. In this study, we explored the adjuvant effect of propolis, Freund and aluminum on the immune response produced in the giant salamander by inactivated Aeromonas hydrophila vaccine. Formalin inactivated Aeromonas hydrophila (1×108 CFU/mL) was prepared and mixed with propolis, Freund and aluminum. In addition a no adjuvant group and control group were prepared. Two hundred and fifty healthy giant salamanders of (40±5cm, 85±6g) were randomly assigned to five treatment groups for inoculation by intraperitoneal injection, with the control group vaccinated with an equal volume of DPBS. Peripheral blood samples for each group were collected from the giant salamanders on day 1, 4, 7, 14, 21, 28 and 35 post-immunization for a serum agglutinating antibody assay. The challenge test with Aeromonas hydrophila was performed on d 35 post-immunization and 20 giant salamanders in each group were selected for the test. After two weeks, death and prevalence rates were calculated. Results show that the serum agglutinating antibody titers of the giant salamanders in the propolis adjuvant group followed an upward trend from day 1-14 and peaked at 1:469.33 on d 21 post-immunization. The antibody titers of the giant salamanders in the Freund adjuvant group followed an upward trend from day 1-28 and reached the maximum value of 1:448.00 on d 35 post-immunization, then followed a downward trend. The aluminum adjuvant group followed an upward trend from day 1-21 and reached the maximum value of 1:362.67 on d 28 post-immunization. The no adjuvant group peaked at 1:384.00 on d 21 post-immunization, then decreased continuously and antibody titers of the giant salamanders in the control group was at a constant value of 1:4.00. The challenge test with Aeromonas hydrophila shows that the mortality of the propolis adjuvant group, Freund adjuvant group, aluminum adjuvant group and the no adjuvant group were 10%, 20%, 25% and 35%, respectively, and the relative percent survival were 88.9%, 77.8%, 72.2% and 61.1%, respectively. The mortality of the control group was 90%. Thus, our study demonstrates that the immune protection of the bacterial inactivated vaccine can be improved by using immunoadjuvants, especially by propolis.