Key Laboratory of Drug Targeting, Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu, People's Republic of China.
Int J Nanomedicine. 2013;8:1843-54. doi: 10.2147/IJN.S43827. Epub 2013 May 9.
The heterologous deoxyribonucleic acid (DNA) prime-adenovirus (AdV) boost vaccination approach has been widely applied as a promising strategy against human immunodeficiency virus (HIV)-1. However, the problem of inefficient delivery and lack of specificity of DNA vaccine remains a major issue. In this paper, to improve the transfection of DNA vaccine and realize dendritic cell targeting, we used mannosylated polyethyleneimine (man-PEI) as a DNA vector carrier.
The DNA plasmid encoding antigen HIV gag fragment was constructed by polymerase chain reaction. Then the DNA plasmid was complexed with man-PEI. The in vitro transfection efficiency of man-PEI/DNA was analyzed on DC 2.4 cells. Mice were primed with 25 μg pVAX1-HIV gag plasmid complexed with man-PEI, 100 μg naked pVAX1-HIV gag plasmid, or empty pVAX1 vector and boosted by AdV encoding the same antigen. The antibody titer, CD4(+) and CD8(+) T-cell response, as well as interferon-γ and interleukin-4 levels in serum and in splenocytes culture were analyzed using flow cytometry or enzyme-linked immunosorbent assay to evaluate the immune response. To test a long-term effect of the vaccination regimen, CD8(+) memory T-cell was also detected by flow cytometry.
The pVAX1-HIV gag was constructed successfully. The in vitro transfection efficiency in dendritic cells was significantly higher than naked DNA plasmid. Compared with 100 μg naked DNA/AdV group, the immunoglobulin G2a antibody titer, T-cell response percentage, and cytokine production level induced by man-PEI/DNA/AdV group were significantly higher at a lower DNA dose. Also, the man-PEI/DNA could stimulate a memory CD8(+) T-cell response.
Owing to the adjuvant effect of man-PEI, the man-PEI/pVAX1-HIV gag priming plus AdV boosting strategy proved to be a potent vaccine candidate against HIV, which could induce a stronger immune response with a lower DNA dose.
异源脱氧核糖核酸（DNA）疫苗-腺病毒（AdV）加强免疫接种方法已被广泛应用于对抗人类免疫缺陷病毒（HIV）-1。然而，DNA 疫苗传递效率低和缺乏特异性仍然是一个主要问题。在本文中，为了提高 DNA 疫苗的转染效率并实现树突状细胞靶向，我们使用甘露化聚乙烯亚胺（man-PEI）作为 DNA 载体。
通过聚合酶链反应构建编码 HIV gag 片段抗原的 DNA 质粒。然后将 DNA 质粒与 man-PEI 复合。在 DC 2.4 细胞上分析 man-PEI/DNA 的体外转染效率。用 man-PEI 复合的 25 μg pVAX1-HIV gag 质粒、100 μg 裸 pVAX1-HIV gag 质粒或空 pVAX1 载体对小鼠进行初免，并用编码相同抗原的 AdV 加强免疫。用流式细胞术或酶联免疫吸附试验分析血清和脾细胞培养物中的抗体滴度、CD4(+)和 CD8(+)T 细胞反应以及干扰素-γ和白细胞介素-4 水平，以评估免疫反应。为了测试疫苗方案的长期效果，还通过流式细胞术检测 CD8(+)记忆 T 细胞。
成功构建了 pVAX1-HIV gag。在树突状细胞中的体外转染效率明显高于裸 DNA 质粒。与 100 μg 裸 DNA/AdV 组相比，较低 DNA 剂量时，man-PEI/DNA/AdV 组诱导的 IgG2a 抗体滴度、T 细胞反应百分比和细胞因子产生水平均显著升高。而且，man-PEI/DNA 可以刺激记忆性 CD8(+)T 细胞反应。
由于 man-PEI 的佐剂作用，man-PEI/pVAX1-HIV gag 初免加 AdV 加强免疫策略被证明是一种有效的 HIV 疫苗候选物，它可以在较低的 DNA 剂量下诱导更强的免疫反应。
