弓形虫ROP11核酸疫苗免疫保护作用的研究

Study on immunoprotection from toxoplasmosis provided by an ROP11 nuclei acid vaccine

目的观察ROP11核酸疫苗对BALB/c小鼠的免疫保护作用。方法 40只BALB/c小鼠随机分为实验组、空质粒对照组、PBS对照组和空白对照组,每组10只,均通过股四头肌注射免疫小鼠。其中实验组每鼠注射pcDNA3.1(+)-ROP11重组质粒100μg(1μg/μl),空质粒对照组注射pcDNA3.1(+)质粒100μg(1μg/μl),PBS对照组注射无菌PBS缓冲液100μl,空白对照组不注射。共免疫3次,每次间隔2周,末次接种量均加倍。分别于每次注射前和末次注射后第2周检测小鼠血清特异性IgG和细胞因子IFN-γ、IL-2、IL-4、IL-10。末次注射后2周各组小鼠腹腔攻击感染RH株弓形虫速殖子1×103个/只,观察其存活时间,评价免疫效果。结果 ROP11核酸疫苗能诱发小鼠产生细胞免疫和体液免疫反应,实验组小鼠血清特异IgG随着免疫次数的增加而显著增高(P<0.05)。血清IFN-γ、IL-2、IL-4、IL-10均不同程度升高(P<0.05)。重组质粒免疫组、空质粒免疫组、PBS和空白对照组小鼠经RH株弓形虫攻击感染后的平均存活时间为236.3、97.8、96.3和96.2h,差异有统计学意义(P<0.05)。结论 ROP11核酸疫苗对BALB/c小鼠弓形虫感染有一定的免疫保护性,为进一步研究ROP11核酸疫苗的生物学功能提供了实验基础。

Objective To observe the immunoprotection provided by an ROP11 nuclei acid vaccine in mice. Methods Forty BALB/C mice were randomly divided into an experimental group,an empty plasmid group,a PBS control group,and a blank control group with 10 mice in each group.The mice were immunized via injection in the quadriceps femoris.The experimental group was injected with 100μg（1μg/μl）of the recombinant plasmid pcDNA3.1（＋）-ROP11,the empty plasmid group was injected with 100ug（1μg/μl）of the pcDNA3.1（＋）plasmid,the PBS group was injected with 100μl of PBS buffer,and the blank control group was not injected.Each immunization was done a total of three times with an interval of 2weeks.During the final injection,the injected dose was doubled for all mice.Before each injection and two weeks after the final injection,levels of serum IgG antibodies and cytokines（IFN-γ,IL-2,IL-4,and IL-10）were measured.Mice in all of the groups were challenged intraperitoneally（IP）with 1×10^3tachyzoites of the RH strain of Toxoplasma gondii two weeks after the final injection to observe their survival time and evaluate immunity. Results The vaccine induced a strong cellular response and a strong humoral immune response.The experimental group had a significantly higher level of serum IgG antibodies the more times the group was immunized（P〈0.05）.The experimental group had higher levels of IFN-γ,IL-2,IL-4,and IL-10 in serum than did the control groups（P〈0.05）.After mice were challenged with tachyzoites of the RH strain of T.gondii,the experimental group had a mean survival time of 236.3h,the empty plasmid group had a mean survival time of 97.8h,the PBS control group had a mean survival time of 96.3h,and the blank control group had a mean survival time of 96.2h.There were statistically significant differences in the mean survival time（P〈0.05）. Conclusions The recombinant ROP11 nuclei acid vaccine provided BALB/C mice with some immunoprotection against toxoplasmosis.This finding has provided an experimental basis for further study of the biological functions of the ROP11 gene and nucleic acid vaccines against T.gondii.