Yang Wen-Bin, Wang Jin-Lei, Gui Qian, Zou Yang, Chen Kai, Liu Qing, Liang Qin-Li, Zhu Xing-Quan, Zhou Dong-Hui
Key Laboratory of Fujian-Taiwan Animal Pathogen Biology, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.
State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China.
Front Microbiol. 2019 Aug 13;10:1875. doi: 10.3389/fmicb.2019.01875. eCollection 2019.
Toxoplasmosis, one of the most important health-threatening diseases worldwide, is caused by , which infects a wide range of warm-blooded animals and humans, leading to enormous health and socioeconomic concerns. can establish chronic infection to evade the immune response in hosts. Once a chronic infection has been established, the available treatments cannot efficiently control this stage of efficiently. Moreover, the available treatments rely only on a few drugs, such as sulfapyridine and pyrimethamine, that tend to have severe side effects. Given these factors, vaccination has been considered to be the most efficient method to prevent and control this disease. However, there is currently lack of effective vaccine available for use to prevent toxoplasmosis apart form Toxovax, the only available vaccine, which is used in sheep to prevent abortion. To address this problem, we knocked out the gene of the type I strain using the CRISPR-Cas9 system, constructed a live-attenuated vaccine and evaluated its protective efficacy in a mouse model. Immunization of mice with RH:Δ induced a high level of -specific IgG1, IgG2a and total IgG 42 days after immunization. There was a significant increase in the levels of cytokines in the splenocyte suspensions of RH:Δ-infected mice, and a mixed Th1/Th2 response was induced in the mice. Remarkably, after heterologous challenges with tachyzoites of the RH, PYS and Pru strains and cysts of the Pru strain by different infection routes, the immunized animals were protected from toxoplasmosis with a 100% survival rate, in both acute and chronic infection. In addition, compared with control mice, the Pru cyst load was clearly reduced in the brains of RH:Δ-infected immunization-mice. Our study demonstrated that the RH:Δ strain was able to evoke strong anti- immune responses and provide effective protection against parasite strains with different levels of virulence, suggesting that the RH:Δ strain may represent a promising live-attenuated vaccine against toxoplasmosis, which is worthy of further evaluation in food-producing animals and in definitive feline host.
弓形虫病是全球最重要的威胁健康的疾病之一，由弓形虫引起，它可感染多种温血动物和人类，引发巨大的健康和社会经济问题。弓形虫能够建立慢性感染以逃避宿主的免疫反应。一旦建立慢性感染，现有的治疗方法无法有效控制弓形虫的这一阶段。此外，现有的治疗仅依赖少数几种药物，如磺胺吡啶和乙胺嘧啶，这些药物往往有严重的副作用。鉴于这些因素，疫苗接种被认为是预防和控制这种疾病的最有效方法。然而，除了用于预防绵羊流产的唯一可用疫苗Toxovax外，目前缺乏可用于预防弓形虫病的有效疫苗。为了解决这个问题，我们使用CRISPR-Cas9系统敲除了I型弓形虫菌株的某基因，构建了一种减毒活疫苗，并在小鼠模型中评估了其保护效力。用RH:Δ免疫小鼠42天后，诱导产生了高水平的特异性IgG1、IgG2a和总IgG。感染RH:Δ的小鼠脾细胞悬液中细胞因子水平显著升高，小鼠体内诱导产生了混合的Th1/Th2反应。值得注意的是，在通过不同感染途径用RH、PYS和Pru菌株的速殖子以及Pru菌株的包囊进行异源攻击后，免疫动物在急性和慢性感染中均以100%的存活率免受弓形虫病感染。此外，与对照小鼠相比，感染RH:Δ的免疫小鼠大脑中的Pru包囊负荷明显降低。我们的研究表明，RH:Δ菌株能够引发强烈的抗弓形虫免疫反应，并对不同毒力水平的寄生虫菌株提供有效保护，这表明RH:Δ菌株可能是一种有前景的抗弓形虫病减毒活疫苗，值得在食用动物和终末宿主猫中进行进一步评估。
