College of Animal Science & Veterinary Medicine, Shandong Agriculture University, Tai'an, People's Republic of China.
Immunopharmacol Immunotoxicol. 2010 Jun;32(2):297-306. doi: 10.3109/08923970903311802.
C3d, a split product of C3, interacts with its receptor (CR2 or CD21) on B cells and follicular dendritic cells (FDCs) and is crucial for induction and maintenance of a normal humoral immune response. This fragment of complement protein C3 (C3d) has also been shown to enhance B cell responses when complexed with antigen and C3d fusion increased Th2-biased immune response by inducing IL-4 production.
The gene fragment coding for Chinese Pekin duck (Anas platyrhynchos) C3d gene (duC3d) was cloned and expressed as a component of fusion proteins destined for use in in vitro experiments. Two, four and six copies of CR2-binding domain duC3d-P29 were fused, respectively, to truncated Newcastle disease virus (NDV) F gene encoding soluble glycoprotein F in pcDNA3.1.All recombinant proteins were analyzed by SDS-PAGE and Western immunoblot. BALB/c mice were, respectively, immunized with recombinant plasmids, blank vector, and inactivated vaccine.
The result of immunogenicity detections of The IL-4 level for F-C3d-P29.6 DNA immunization approached that for the inactivated vaccine. Compared to C3d-P29.6, C3d-P29.4 enhanced F DNA immunogenicity to a lesser extent. Furthermore, C3d-P29.n fusion increased Th2-biased immune response by inducing IL-4 production.
We demonstrated that C3d-P29 could enhance immunogenicity by directing Th1-biased to a balanced and more effective Th1/Th2 response. The expression of the duck C3d fusion proteins in this study which was the first reported, and the detections of the cytokine level for F-C3d-P29.n in DNA immunization using the BALB/c mice as the model animal, will provide the basis for immunization trials in chicken or other poultry, studies of receptor binding and cell activation of animal lymphocytes, and investigations of new types of vaccine, including genetic recombinant and DNA vaccines for the future against relevant pathogens.
C3d 是 C3 的裂解产物，与 B 细胞和滤泡树突状细胞（FDC）上的受体（CR2 或 CD21）相互作用，对于诱导和维持正常的体液免疫反应至关重要。这种补体蛋白 C3 的片段（C3d）与抗原形成复合物时也可以增强 B 细胞的反应，并且通过诱导 IL-4 的产生，增加 C3d 融合物的 Th2 偏向性免疫反应。
克隆了编码中国北京鸭（Anas platyrhynchos）C3d 基因（duC3d）的基因片段，并将其作为融合蛋白的一部分进行表达，旨在用于体外实验。将 CR2 结合域 duC3d-P29 的两个、四个和六个拷贝分别融合到截短的新城疫病毒（NDV）F 基因编码的可溶性糖蛋白 F 中，构建到 pcDNA3.1 中。所有重组蛋白均通过 SDS-PAGE 和 Western 免疫印迹进行分析。BALB/c 小鼠分别用重组质粒、空载体和灭活疫苗进行免疫。
F-C3d-P29.6 DNA 免疫的 IL-4 水平接近灭活疫苗。与 C3d-P29.6 相比，C3d-P29.4 对 F DNA 免疫原性的增强作用较小。此外，C3d-P29.n 融合通过诱导 IL-4 的产生增加了 Th2 偏向性免疫反应。
我们证明了 C3d-P29 通过将 Th1 偏向性引导至平衡和更有效的 Th1/Th2 反应来增强免疫原性。本研究首次报道了鸭 C3d 融合蛋白的表达，并在 BALB/c 小鼠模型中检测了 F-C3d-P29.n 的细胞因子水平，这为在鸡或其他禽类中进行免疫试验、研究动物淋巴细胞的受体结合和细胞激活以及研究新型疫苗（包括针对相关病原体的遗传重组和 DNA 疫苗）提供了依据。
