Department of Internal Medicine, Saint Louis University, Saint Louis, Missouri, USA.
PLoS Negl Trop Dis. 2011 Mar 8;5(3):e983. doi: 10.1371/journal.pntd.0000983.
Immunization of mice with the Trypanosoma cruzi trans-sialidase (TS) gene using plasmid DNA, adenoviral vector, and CpG-adjuvanted protein delivery has proven highly immunogenic and provides protection against acute lethal challenge. However, long-term protection induced by TS DNA vaccines has not been reported. The goal of the present work was to test whether the co-administration of a plasmid encoding IL-15 (pIL-15) could improve the duration of protection achieved through genetic vaccination with plasmid encoding TS (pTS) alone.
We immunized BALB/c mice with pTS in the presence or absence of pIL-15 and studied immune responses [with TS-specific IFN-γ ELISPOT, serum IgG ELISAs, intracellular cytokine staining (IFN-γ, TNF-α, and IL-2), tetramer staining, and CFSE dilution assays] and protection against lethal systemic challenge at 1 to 6 months post vaccination. Mice receiving pTS alone developed robust TS-specific IFN-γ responses and survived a lethal challenge given within the first 3 months following immunization. The addition of pIL-15 to pTS vaccination did not significantly alter T cell responses or protection during this early post-vaccination period. However, mice vaccinated with both pTS and pIL-15 challenged 6 months post-vaccination were significantly more protected against lethal T. cruzi challenges than mice vaccinated with pTS alone (P<0.05). Improved protection correlated with significantly higher numbers of TS-specific IFN-γ producing total and CD8(+) T cells detected>6 months post immunization. Also, these TS-specific T cells were better able to expand after in vitro re-stimulation.
Addition of pIL-15 during genetic vaccination greatly improved long-term T cell survival, memory T cell expansion, and long-term protection against the important human parasite, T. cruzi.
用质粒 DNA、腺病毒载体和 CpG 佐剂蛋白递送来使小鼠免疫接种克氏锥虫 trans-sialidase（TS）基因已被证明具有高度免疫原性，并能提供针对急性致死性挑战的保护。然而，TS DNA 疫苗诱导的长期保护尚未见报道。本研究的目的是测试共给予编码白细胞介素 15（pIL-15）的质粒是否能改善仅用编码 TS（pTS）的质粒进行基因接种所获得的保护持续时间。
我们用 pTS 免疫 BALB/c 小鼠，同时或不同时给予 pIL-15，并研究免疫反应[用 TS 特异性 IFN-γ ELISPOT、血清 IgG ELISA、细胞内细胞因子染色（IFN-γ、TNF-α 和 IL-2）、四聚体染色和 CFSE 稀释测定]和对致死性全身挑战的保护作用，在接种后 1 至 6 个月进行。单独用 pTS 免疫的小鼠产生了强烈的 TS 特异性 IFN-γ 反应，并在免疫后 3 个月内的一次致死性挑战中存活下来。将 pIL-15 加入 pTS 疫苗接种中并没有显著改变早期接种后的 T 细胞反应或保护作用。然而，在接种后 6 个月接受 pTS 和 pIL-15 两者接种的小鼠比单独用 pTS 接种的小鼠在接受致死性 T. cruzi 挑战时受到更好的保护（P<0.05）。更好的保护与在免疫后 6 个月检测到的更高数量的 TS 特异性 IFN-γ 产生的总 T 细胞和 CD8+T 细胞相关，这些细胞在体外再刺激后能够更好地扩增。
在基因接种过程中添加 pIL-15 大大改善了长期 T 细胞存活、记忆 T 细胞扩增和对重要人类寄生虫 T. cruzi 的长期保护。
