State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, CAAS, Lanzhou, Gansu Province 730046, PR China.
Vaccine. 2011 Sep 2;29(38):6614-9. doi: 10.1016/j.vaccine.2011.06.110. Epub 2011 Jul 14.
Toxoplasma gondii is an obligate intracellular protozoan parasite infecting mammals and birds including humans. Rhoptry protein 18 has been implicated as an important virulence factor. In this study, we constructed a DNA vaccine expressing rhoptry protein 18 (ROP18) of T. gondii, and evaluated the immune response and protective immunity in Kunming mice. The gene sequence encoding ROP18 was inserted into the eukaryotic expression vector pVAX I. Intramuscular immunization of mice with pVAX-ROP18 elicited specific humoral responses and stimulated lymphoproliferation (P<0.05). The cellular immune response was associated with the production of IFN-γ, indicating that a Th1 type response was elicited, which was confirmed by the production of large amounts of IgG2a (P<0.05). By the expression of the CD69, an activation marker of CD4+ and CD8+ T cells, we found that pVAX-ROP18 enhanced the activation of CD4+ and CD8+ T cells in lymphoid in mice. After lethal challenge, the mice immunized with the pVAX-ROP18 showed a significantly increased survival time (27.9±15.1 days) compared with control mice which died within 7 days of challenge (P<0.05). Our results show for the first time, that a ROP18 vaccine construct can enhance the T. gondii-specific CTL. Th1 responses and increased survival suggested that ROP18 is a promising vaccine candidate against infection with T. gondii.
刚地弓形虫是一种专性细胞内寄生的原虫，感染包括人类在内的哺乳动物和鸟类。 顶复蛋白 18 被认为是一种重要的毒力因子。 在这项研究中，我们构建了一种表达刚地弓形虫顶复蛋白 18（ROP18）的 DNA 疫苗，并在昆明小鼠中评估了免疫反应和保护免疫。 ROP18 的基因序列被插入真核表达载体 pVAX I 中。 用 pVAX-ROP18 肌肉内免疫小鼠引起了特异性体液反应，并刺激了淋巴细胞增殖（P<0.05）。 细胞免疫反应与 IFN-γ 的产生有关，表明引发了 Th1 型反应，这通过大量 IgG2a 的产生得到了证实（P<0.05）。 通过 CD69 的表达，即 CD4+和 CD8+T 细胞的激活标志物，我们发现 pVAX-ROP18 增强了小鼠淋巴中的 CD4+和 CD8+T 细胞的激活。 在致死性攻击后，用 pVAX-ROP18 免疫的小鼠的存活时间明显延长（27.9±15.1 天），而对照小鼠在攻击后 7 天内死亡（P<0.05）。 我们的结果首次表明，ROP18 疫苗构建体可以增强弓形虫特异性 CTL。 Th1 反应和存活率的增加表明 ROP18 是一种有前途的弓形虫感染疫苗候选物。
