B细胞表位作图研究进展

抗原-抗体的特异性结合是由抗体表面的抗原决定簇与抗原表面的表位基序间的特异性互补识别决定的。B细胞表位作图既包括B细胞抗原表位基序的鉴定(即确定抗原分子上被B细胞表面受体或抗体特异性识别并结合的氨基酸基序),也包括绘制抗原蛋白的全部或接近全部的B细胞表位基序在其一级或高级结构上的分布图谱的过程。B细胞表位作图是研发表位疫苗、治疗性表位抗体药物和建立疾病免疫诊断方法的重要前提。目前,已经建立了多种B细胞表位鉴定或绘制抗原蛋白B细胞表位图谱的实验方法。基于抗原-单抗复合物晶体结构的X-射线晶体学分析的B细胞表位作图和基于抗原蛋白或抗原片段的突变体库筛选技术的B细胞表位作图可以在氨基酸水平,甚至原子水平上揭示抗原分子上与单抗特异性结合的关键基序;其它B细胞表位作图方法(如基于ELISA的肽库筛选技术)常常只能获得包含B细胞表位的抗原性肽段,因而,很少用于最小表位基序的鉴定;而改良的生物合成肽法多用于B细胞表位的最小基序鉴定和精细作图。鉴于每种B细胞作图方法都存在各自的优势与不足,B细胞表位作图往往需要多种作图方法的有机结合。本文对目前常用的B细胞表位作图的实验方法及其在动物疫病防控中的应用进行综述,以期为研究者设计最佳的表位作图方案提供参考。

Progresses on B cell epitope mapping

The specific interaction between antigen and antibody is determined by the specific complementary recognition between antigenic determinant and epitope motif on the surfaces of antibody and antigen, respectively. B cell epitope mapping involves both the fine location of B cell epitopes (location of the specific motifs on an antigen recognized and bound by antibodies) and the depiction of the distribution of all or nearly all epitopes of an antigen on its primary or secondary structure. Mapping of B cell epitopes constitutes a primary basis for the development of epitope-based vaccines and therapeutic epitope specific antibodies and the establishment of immunological diagnostic methods. So far, a number of experimental methods have been developed to map the B cell epitopes recognized by antibodies or to depict the map of epitopes on an antigen. B cell epitope mapping methods based on X-ray crystallography of antigen-mAb (monoclonal antibody) complex and screening of the mutant libraries of an antigenic protein or its fragments can reveal the key residues of antigen specifically bound by mAb at amino acid or even atom level. Other epitope mapping methods, such as peptide library screening technology using ELISA, are seldom used to identify the minimum epitope motifs because only the antigenic fragments can be obtained by these methods. On the other hand, the improved biosynthetic peptide method is usually used for the minimal motif identification and fine mapping of B cell epitopes. It is quite common that more than one methods were employed to fine map B cell epitopes due to the respective limitations of each method. This review discusses and compares different experimental methods commonly used in B cell epitope mapping and aims to assist researchers to design the most suitable protocol to map their B cell epitopes. The applications of B cell epitope mapping in animal disease prevention and control are also reviewed.