Liu D, Niu Z-X
College of Animal Science and Veterinary Medicine, Shandong Agriculture University, Tai'an, China.
Scand J Immunol. 2008 Dec;68(6):598-606. doi: 10.1111/j.1365-3083.2008.02177.x.
The terminal degradation product (C3d) of mammalian complement component C3 plays an important role in modulation of the adaptive immune response through the interaction with complement receptor type 2 (CR2) on B cells. In this study, the gene fragment coding for the complement protein C3d (chC3d) from Roman chicken was cloned and expressed as a fusion protein for its application in the vaccine study of chicken, and for in vitro experiments. The chC3d fragment strengthened B-cell responses when complexed with antigen. Three potential vaccine construct units were engineered to contain two, four and six copies of chC3d coding gene linked to the F gene of Newcastle disease virus (NDV), an economically important pathogen of chicken that is classified as a list A contagious disease of poultry by the Office International des Epizooties. The cloned chC3d protein and different repeats of C3d proteins in addition to the F gene of NDV were generated separately in Escherichia coli and chicken embryo fibroblast cells with the help of expression vectors. All recombinant proteins were analysed by SDS-PAGE and Western blotting. Analysis of the immunogenicity of different repeats of C3d revealed that chC3d had an enhancing effect on the immunogenicity of antigens, and that six or more repeats of C3d may be necessary for efficient enhancement of antigen-specific immune responses. To date, published research into the adjuvant activities of C3d has been limited to experiments in mice, rabbits and cattle. The adjuvant properties of C3d have not been assessed in poultry using homologous C3d in association with antigens relevant to the target species. The Roman chicken C3d fusion proteins described in this study is the first report and will provide a basis for immunization trials in chicken, studies of receptor binding and cell activation of chicken lymphocytes, and investigations of new types of vaccines, including recombinant vaccines and DNA vaccines for future use against other pathogens in chicken.
哺乳动物补体成分C3的终末降解产物（C3d）通过与B细胞上的2型补体受体（CR2）相互作用，在调节适应性免疫反应中发挥重要作用。在本研究中，克隆了罗曼鸡补体蛋白C3d（chC3d）的编码基因片段，并将其表达为融合蛋白，用于鸡的疫苗研究及体外实验。当与抗原复合时，chC3d片段可增强B细胞反应。构建了三种潜在的疫苗构建单元，分别包含与新城疫病毒（NDV）F基因相连的两个、四个和六个拷贝的chC3d编码基因，NDV是鸡的一种重要经济病原体，被国际兽疫局列为A类家禽传染病。借助表达载体，在大肠杆菌和鸡胚成纤维细胞中分别单独表达克隆的chC3d蛋白以及除NDV F基因外不同重复次数的C3d蛋白。所有重组蛋白均通过SDS-PAGE和蛋白质印迹法进行分析。对不同重复次数的C3d免疫原性分析表明，chC3d对抗原免疫原性具有增强作用，且C3d重复六次或更多次可能是有效增强抗原特异性免疫反应所必需的。迄今为止，关于C3d佐剂活性的已发表研究仅限于在小鼠、兔子和牛身上进行的实验。尚未使用同源C3d与目标物种相关抗原结合，在家禽中评估C3d的佐剂特性。本研究中描述的罗曼鸡C3d融合蛋白是首次报道，将为鸡的免疫试验、鸡淋巴细胞受体结合和细胞活化研究以及包括重组疫苗和DNA疫苗在内的新型疫苗研究提供基础，这些新型疫苗未来可用于抵抗鸡的其他病原体。
