Immunization with Toxoplasma gondii GRA17 Deletion Mutant Induces Partial Protection and Survival in Challenged Mice.
Immunization with Toxoplasma gondii GRA17 Deletion Mutant Induces Partial Protection and Survival in Challenged Mice.
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弓形虫 GRA17 缺失突变体免疫可诱导受攻击小鼠的部分保护和存活
DOI：
10.3389/fimmu.2017.00730
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发表时间：
2017
影响因子：
7.3
通讯作者：
Zhu XQ
中科院分区：
文献类型：
--
作者：
Wang JL;Elsheikha HM;Zhu WN;Chen K;Li TT;Yue DM;Zhang XX;Huang SY;Zhu XQ
弓形虫病仍然是一种威胁世界的疾病，主要是因为缺乏完全有效的疫苗。在这里，我们使用CRISPR-Cas9方法通过破坏毒力因子GRA17创建了ΔGRA17突变体。然后，我们测试了ΔGRA17速殖子是否可以用作小鼠急性、慢性和先天性弓形虫感染的减毒活疫苗。ΔGRA17免疫引起的免疫应答提示有顺序的Th1和Th2 T细胞应答，分别在免疫后28天和70天表现为高水平的Th1和混合的Th1/Th2细胞因子。ΔGRA17-mediated免疫完全保护小鼠免受野生型（wt） RH菌株、中国弓形虫9基因型PYS、TgC7菌株和弓形虫Pru菌株的致死性感染。免疫小鼠（53±15个/脑）比未免疫小鼠（4296±687个/脑）脑内囊负荷显著降低（P < 0.05）。在先天性感染方面，ΔGRA17-immunized坝出生的幼崽产仔数、成活率和体重（BW）与naïve对照坝出生的幼崽没有差异（P = 0.24）。然而，未接种疫苗和感染疫苗的母鼠产仔数（P < 0.001）、存活率和体重（P < 0.01）显著降低。此外，与未接种和感染II型Pru菌株的坝相比，免疫后感染II型Pru菌株的坝脑囊肿负荷显著（P < 0.001）减少。这些发现表明，ΔGRA17菌株免疫唤起细胞介导和中和抗体反应，并提供一定程度的保护，以抵御同源和异源毒性弓形虫菌株的攻击。
Toxoplasmosis remains a world-threatening disease largely because of the lack of a fully effective vaccine. Here, we created a ΔGRA17 mutant by disrupting the virulence factor GRA17 using CRISPR-Cas9 method. Then, we tested whether ΔGRA17 tachyzoites can be used as a live-attenuated vaccine against acute, chronic, and congenital Toxoplasma gondii infection in mice. Immune response evoked by ΔGRA17 immunization suggested a sequential Th1 and Th2 T cell response, indicated by high levels of Th1 and a mixed Th1/Th2 cytokines at 28 and 70 days after immunization, respectively. ΔGRA17-mediated immunity fully protected mice against lethal infection with wild-type (wt) RH strain, heterologous challenge with PYS, and TgC7 strains of the Chinese ToxoDB#9 genotype, and T. gondii Pru strain. Although parasite cysts were detected in 8 out of 10 immunized mice, cyst burden in the brain was significantly reduced (P < 0.05) in immunized mice (53 ± 15 cysts/brain) compared to non-immunized mice (4,296 ± 687 cysts/brain). In respect to congenital infection, the litter size, survival rate, and body weight (BW) of pups born to ΔGRA17-immunized dams were not different compared to pups born to naïve control dams (P = 0.24). However, a marked reduction in the litter size (P < 0.001), survival rate, and BW (P < 0.01) of pups born to non-immunized and infected dams was detected. Also, immunized dams infected with type II Pru strain had significantly (P < 0.001) less cyst burden in the brain compared with non-immunized and infected dams. These findings show that immunization with ΔGRA17 strain evokes cell-mediated and neutralizing antibody responses and confers some degree of protection against challenge with homologous and heterologous virulent T. gondii strains.