科研动态

纳米抗体（nanobody，Nb）是在骆驼血清中发现的一种新型抗体，具有相对分子质量小、稳定性高、亲和力高、组织渗透性强以及可识别抗原缝隙表位、进一步改造和表达等特点。Nb筛选技术分为噬菌体展示、酵母双杂交、mRNA展示以及高通量测序和质谱分析等4种，它们都能够快速筛选到特异性Nb。对具有高度亲和力的Nb，多种表达系统均可以实现高效表达。其中：原核表达最常用，其操作相对简单、产量大、生产成本低，但要去除表达出的重组蛋白内毒素；酵母表达可以直接收集培养基上清纯化，杂蛋白含量少，但可能存在过度糖基化问题；植物宿主可以大量表达Nb，但基因操作过程繁琐，且分离纯化Nb相对困难；哺乳动物细胞生产抗体也是较常用的方式，但生产成本较高。针对每一种筛选方法和表达系统目前没有统一的评价标准，在选择时，应以实验室条件为基础，充分了解筛选对象的结构、功能和用途，根据不同目的选用。本文对Nb结构特点、筛选及表达以及在动物疫病防治中的应用展开论述，可为相关领域研究提供技术支持。

Research Progress on the Screening and Expression of Nanobody

Nanobody（Nb），a new antibody found in camel serum，is characterized by small molecular weight，high stability，high affinity，strong tissue permeability，and recognition of antigen gap epitopes，further modification and expression. Nb screening technology includes phage display，yeast double hybridization，mRNA display and high-throughput sequencing and mass spectrometry analysis，all of which could rapidly screen specific Nb. For the Nb with high affinity，many expression systems could be used to realize an effectively expression. Specifically，prokaryotic expression is mostly used due to its simple operation，mass production and low production cost，but the output of recombinant protein endotoxin should be removed；yeast expression could be used to directly collect purification of medium supernatant，with small content of miscellaneous protein，but excessive glycosylation may be available；host plants could express Nb in large quantity，but the process of gene operation is complicated and it is difficult to isolate and purify Nb；antibody produced by cells of mammals is also usually used，but its production cost is high. No uniform evaluation standard has been developed for all the above methods and expression systems till now. A decision should be made based on laboratory conditions and according to corresponding purpose provided that the structure，function and usage of the object to be screened should be well understood. In the paper，the structure，screening and expression of Nb as well as its application in the prevention and control of animal diseases were discussed，which might technically support the study in related fields.

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