壳聚糖-DNA疫苗预防空肠弯曲菌感染的实验研究

Experimental study on the chitosan-DNA vaccines against campylobacter jejuni invasion

目的研究壳聚糖-DNA 疫苗预防空肠弯曲菌感染的效力。方法采用壳聚糖分别包裹空肠弯曲菌主要外膜蛋白和黏附蛋白编码基因 cadF 和 peblA 的真核表达重组质粒 pcDNA3.1(+)-cadF 和 pcDNA3.1(+)-peblA,制备壳聚糖-DNA 疫苗。以未干预、空质粒、单纯壳聚糖组为对照,分别将含60μg DNA 的不同效价疫苗于实验开始的0、7、14和21d 滴鼻免疫 BALB/c 小鼠,末次免疫后8周采用空肠弯曲菌 HS:19重复攻击的方式进行灌胃攻击。攻击后,对该疫苗的临床保护效-率和防御空肠弯曲菌感染的效应进行评价。结果空肠弯曲菌壳聚糖-DNA 疫苗滴鼻免疫小鼠后,不仅诱导了高水平的血清 IgA 和 IgG 抗体,而且诱导了高水平的黏膜 IgA 抗体,末次免疫后第4周其 P/N 值分别达20.58、30.13和6.87,末次免疫后第8周其肠壁 SIgA 免疫组织化学染色显示呈"+++"反应。并且,其诱导的特异性免疫应答能有效保护免疫后小鼠免遭空肠弯曲菌的感染攻击,其疫苗的有效性高达93.70。结论壳聚糖-DNA 疫苗能有效预防空肠弯曲菌的感染攻击。

Objective The immunogenicity and protective efficacy of an experimental Campylobacterjejuni（ C. jejuni） chitosan-DNA vaccines were evaluated in mice. Methods The chitosan- DNA vaccines were prepared by embedding pcDNA3. 1 （ ＋ ） -cadF and pcDNA3. 1 （ ＋ ） -peblA with chitosan respectively. BALB/c mice were intranasally immunized in a four-dose primary series （7 d intervals ） at doses of 60 μg chitosan-DNA vaccines each time. The comparative immunogenicities of nine formulations were assessed on the basis of the generation of antigen-specific antibodies in serum and intestinal secretions. Mice were attacked repeatedly through intragastric administration of C. jejuni HS： 19 at the 8th week after the immunization and protective efficacy was determined by detecting the degrees of protection afforded against C. jejuni invaded. Results The mice immunized with chitosan-DNA vaccines have generated high levels of IgA and lgG from the sera and IgA from the intestinal secretions and the P/N value went up to 20. 58,30. 13 and 6. 87 respectively. Meanwhile, the expression of intestinal SIgA increased correspondingly. Moreover the chitosan-DNA vaccines induced strongest level of protection in BALB/c mice against challenge with C. jejuni HS： 19 strain and the protective efficacies was 93. 70. Conclusion The results of this study indicate that the chitosan-DNA vaccines could induce significant protective immunity against C. jejuni challenge in the mice model.