National Institute of Virology, Pashan Campus, 130/1, Sus Road, Pashan, Pune, India.
Virol J. 2011 Aug 2;8:382. doi: 10.1186/1743-422X-8-382.
Japanese encephalitis virus (JEV) is the leading cause of viral encephalitis, with ~50,000 cases reported annually worldwide. Vaccination is the only measure for prevention. Recombinant vaccines are an efficient and safe alternative for formalin inactivated or live attenuated vaccines. Nowadays, incorporation of molecular adjuvants has been the main strategy for melioration of vaccines. Our attempt of immunomodulation is based on targeting antigen presenting cells (APC) "majorly macrophages" by using macrosialin promoter. We have compared the immune response of the constructed plasmids expressing JEV envelope (E) protein under the control of aforesaid promoter and cytomegalovirus (CMV) immediate early promoter in mouse model. Protection of immunized mice from lethal challenge with JEV was also studied.
The E protein was successfully expressed in the macrophage cell line and was detected using immunofluorescence assay (IFA) and Western blotting. APC expressing promoter showed comparable expression to CMV promoter. Immunization of mice with either of the plasmids exhibited induction of variable JEV neutralizing antibody titres and provided protection from challenge with a lethal dose of JEV. Immune splenocytes showed proliferative response after stimulation with the JEV antigen (Ag), however, it was higher for CMV promoter. The magnitude of immunity provided by APC dominant promoter was non-significantly lower in comparison to CMV promoter. More importantly, immune response directed by APC promoter was skewed towards Th1 type in comparison to CMV promoter, this was evaluated by cytokine secretion profile of immune splenocytes stimulated with JEV Ag.
Thus, our APC-expressing DNA vaccination approach induces comparable immunity in comparison to ubiquitous promoter construct. The predominant Th1 type immune responses provide opportunities to further test its potency suitable for response in antiviral or anticancer vaccines.
日本脑炎病毒（JEV）是病毒性脑炎的主要原因，全球每年报告约 50,000 例病例。疫苗接种是预防的唯一措施。重组疫苗是福尔马林灭活或减毒活疫苗的有效和安全替代品。如今，将分子佐剂纳入是改善疫苗的主要策略。我们的免疫调节尝试是基于使用巨唾液酸蛋白启动子靶向抗原呈递细胞（APC）“主要是巨噬细胞”。我们比较了在小鼠模型中表达 JEV 包膜（E）蛋白的构建质粒在上述启动子和巨细胞病毒（CMV）早期启动子控制下的免疫反应。还研究了免疫接种小鼠对 JEV 致死性攻击的保护作用。
E 蛋白在巨噬细胞系中成功表达，并通过免疫荧光检测（IFA）和 Western blot 检测。表达 APC 的启动子与 CMV 启动子的表达相当。用任一种质粒免疫小鼠均可诱导可变 JEV 中和抗体滴度，并提供对致死剂量 JEV 攻击的保护。用 JEV 抗原刺激免疫脾细胞后显示出增殖反应，但 CMV 启动子更高。与 CMV 启动子相比，APC 优势启动子提供的免疫程度没有显着降低。更重要的是，与 CMV 启动子相比，由 APC 启动子指导的免疫反应偏向 Th1 型，这是通过用 JEV 抗原刺激免疫脾细胞后的细胞因子分泌谱来评估的。
因此，我们的 APC 表达 DNA 疫苗接种方法与普遍的启动子构建体相比可诱导相当的免疫反应。主要的 Th1 型免疫反应为进一步测试其在抗病毒或抗癌疫苗中的效力提供了机会。
