人源性抗HBsAg抗体Fab段噬菌体呈现文库的构建、筛选及阳性克隆核苷酸序列测定

目的:构建一个经HBsAg主动免疫的人lgG1抗体噬菌体展示文库,通过特异的淘筛(panning)获得与HBsAg有较高亲和力的Fab抗体,并测定其编码序列。方法:从一经乙肝疫苗免疫的自愿者的外周血分离淋巴细胞提取RNA,逆转录合成cDNA。PCR扩增重链Fd和κ轻链cDNA。依次将PCR产物克隆进载体pComb3H相应的位点,构建成噬菌体呈现库,并以HBsAg包被的96孔板对抗体库进行3轮淘筛,将所获克隆分别与HBsAg进行ELISA反应,挑取显色大于对照20倍以上的阳性克隆进行DNA测序。结果:lgG1的Fd段和κ轻链cDNA得到扩增,构建了一实际库容量为1.8×10⁵的噬菌体呈现文库。通过特异性淘筛,获得与HBsAg有较高新合力的3株Fab抗体并测定其编码序列。DNA序列测定结果表明,3株抗体中两株的Fd段完全一样,且3株的轻链完全一样。结论:成功构建了一个经HBsAg抗原免疫的人源抗体Fab段噬菌体抗体库,筛选得到了3株特异性抗体的Fab片段。

Screening of phage antibodies against HBsAg from the constructed phage display library and sequencing of the positive clones

AIM:Screening of phage antibodies against HBsAg from the constructed phage display library and sequencing of the positive clones.METHODS:RNAs were extracted from blood lymphocytes of a HBsAg-immunized volunteer. Then cDNAs were synthesized by RT-PCR. To construct the phage antibody display library, cDNAs of Fd fragments and κ chains of the antibodies were amplified through PCR and were inserted into vector pComb3H. Three rounds panning against coated HBsAg showed the specific enrichment of phage antibody. Positive clones were selected and sequenced.RESULTS:A phage antibody display library was constructed after amplifing of Fd fragments and κ chains of IgG1. Three Fab antibodies from the library were selected and sequenced. The result of sequencing showed that two of the three antibodies had the same Fd fragment and all of the three had the same light chain. CONCLUSION:The phage antibody display library was constructed successfully and three specific antibodies (Fab fragments) have been obtained from it.