抗人CD20纳米抗体的筛选、表达及特性分析

目的筛选出抗人CD20纳米抗体序列,并获得具有高亲和力与特异性的抗CD20-人IgG Fc纳米抗体。方法利用天然噬菌体纳米抗体库,以生物素化的CD20抗原为靶标进行4轮液相亲和筛选,采用ELISA鉴定阳性克隆;将筛选到的阳性克隆基因序列与人IgG Fc片段偶联,构建到原核表达载体pCZN1中,并转化至大肠杆菌Arctic Express,经异丙基-β-D-硫代半乳糖苷(IPTG)低温诱导重组蛋白的表达,利用Ni柱进行亲和纯化;ELISA和Western blot法鉴定纯化产物。结果筛选得到了一条重复性高且亲水性好的CD20纳米抗体序列,纯化获得了纯度高达85%以上的抗CD20-人IgG Fc纳米抗体。ELISA结果显示其与CD20抗原具有较高亲和力, Western blot结果表明该抗体能特异性识别CD20抗原。结论利用天然噬菌体纳米抗体库成功获得了抗CD20纳米抗体序列,经纯化的抗CD20-人IgG Fc纳米抗体具有高亲和力与特异性。

Screening,expression and characterization of anti-human CD20 nanobodies

Objective To screen the sequence of nanobodies against human CD20, and obtain anti-CD20-human IgG Fc nanobodies with high affinity and specificity. Methods Based on the na6 ve phage display library, 4 rounds of liquid affinity screening were performed using biotinylated CD20 antigen as the target, and positive clones were identified by ELISA. Prokaryotic expression vector CD20-IgG Fc/pCZN1 was constructed and transformed into E.coli Arctic Express, and the expression of the recombinant protein was induced by IPTG at low temperature and purified by Ni column. The purified product was identified by ELISA and Western blot analysis. Results The specific CD20 nanobody showed good repeatability and hydrophilicity. The purity of anti-CD20-human IgG Fc nanobodies was higher than 85%. ELISA indicated that anti-CD20-human IgG Fc nanobodies had high affinity with CD20 antigen, and Western blot analysis demonstrated they could specifically recognize CD20 antigen. Conclusion The sequence of anti-CD20 nanobody was successfully obtained using the na6 ve phage nanobody library. The purified anti-CD20-human IgG Fc nanobody has high affinity and specificity.