Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, China.
Zhejiang Provincial Institute of Parasitic Diseases, Hangzhou, China.
Front Immunol. 2019 Mar 6;10:418. doi: 10.3389/fimmu.2019.00418. eCollection 2019.
causes infections in a wide range of intermediate hosts and remains a threatening disease worldwide because of the lack of effective drugs and vaccines. Dense granule protein 24 (GRA24) is a novel essential virulence factor that is transferred into the nucleus of host cells from the parasitophorous vacuole to regulate gene expression. In the present study, bioinformatic analysis showed that GRA24 had a high score for B-cell and T-cell epitopes compared with surface antigen 1 (SAG1), which has been studied as a promising vaccine candidate. As a DNA vaccine, pVAX1-GRA24 was injected intramuscularly into BALB/c mice and the induced immune response was evaluated. pVAX1-GRA24 induced high levels of a mixed Th1/Th2 cytokines at 6 weeks after immunization. Antibody determinations, cytokines [interferon gamma (IFN-γ), interleukin (IL)-12, IL-4, IL-10], antigen-specific lymphocyte proliferation, CD4+ and CD8+ T lymphocytes, and cytotoxic T lymphocyte activity showed that mice immunized with pVAX1-GRA24 produced specific humoral and cellular immune responses. The expression levels of interferon regulatory factor 8 (IRF8), nuclear factor kappa B (NF-κB), and T-Box 21 (T-bet) were significantly higher in the pVAX1-GRA24 immunization group than in the control groups. Survival times were prolonged significantly (24.6 ± 5.5 days) in the mice immunized with pVAX1-GRA24 compared with the mice in the control groups, which died within 7 days of challenge ( < 0.05). The results of the present study showed that pVAX1-GRA24 induced a -specific immune response and thus represents a promising candidate vaccine to treat toxoplasmosis.
刚地弓形虫是一种专性细胞内寄生的机会性致病原虫，能够感染包括人类在内的多种中间宿主，引起广泛的临床疾病，目前尚无有效的治疗药物和疫苗，仍是全球范围内严重威胁人类健康的公共卫生问题。致密颗粒蛋白 24（GRA24）是一种新型的必需毒力因子，它从寄生泡转移到宿主细胞的核内，调节基因表达。本研究通过生物信息学分析发现，与作为有希望的疫苗候选物的表面抗原 1（SAG1）相比，GRA24 具有较高的 B 细胞和 T 细胞表位评分。作为一种 DNA 疫苗，将 pVAX1-GRA24 肌肉内注射到 BALB/c 小鼠中，并评估诱导的免疫应答。pVAX1-GRA24 在免疫后 6 周诱导高水平的混合 Th1/Th2 细胞因子。抗体测定、细胞因子（干扰素 γ（IFN-γ）、白细胞介素（IL）-12、IL-4、IL-10）、抗原特异性淋巴细胞增殖、CD4+和 CD8+T 淋巴细胞和细胞毒性 T 淋巴细胞活性表明，用 pVAX1-GRA24 免疫的小鼠产生了特异性的体液和细胞免疫应答。与对照组相比，pVAX1-GRA24 免疫组干扰素调节因子 8（IRF8）、核因子 kappa B（NF-κB）和 T 盒 21（T-bet）的表达水平显著升高。与对照组相比，用 pVAX1-GRA24 免疫的小鼠的存活时间显著延长（24.6±5.5 天），而对照组的小鼠在挑战后 7 天内死亡（<0.05）。本研究结果表明，pVAX1-GRA24 诱导了特异性免疫应答，因此是治疗弓形虫病的一种有前途的候选疫苗。
