一株乙型肝炎病毒鼠单抗的人源化及生物学活性鉴定

Humanization of Therapeutic Antibody of One Hepatitis B Virus and Identification of Its Biological Activity

乙型肝炎病毒(HBV)感染是全球最为重要的公共卫生问题之一,目前临床上治疗HBV的药物在彻底清除病毒方面并没有取得满意的结果,因此迫切需要发展能有效清除病毒,尤其是能有效清除乙肝表面抗原(HBsAg)或大幅度降低HBsAg血清学水平的创新性治疗药物.筛选到一株针对HBV和HBsAg上一个特定表位的鼠单抗129G1,它能持续有效地清除转基因小鼠体内的HBV及HBsAg,有发展为治疗性抗体药物的潜力.为了降低129G1的免疫原性,采用互补决定区(CDR)移植的方式,利用噬菌体抗体库技术对这个鼠单抗进行了人源化,最终得到人源化抗体.人源化抗体与HBsAg的结合活性与嵌合抗体相当,抗体质量浓度为1.45μg/mL时介导THP-1细胞吞噬率达到50%.在HBV转基因小鼠的实验中,获得的129G1人源化抗体能持续有效地抑制血清中HBV DNA及清除HBsAg.

Hepatitis B virus （HBV） infection is a major global health problem. However, current treatments are not satisfactory in removing virus thoroughly from patients, thus we need innovative treatment strategies to remove virus continuously, especially in suppressing the levels of HBsAg and HBV DNA in vivo profoundly and persistently.In this study we discovered 129G1 mAh,which is a mouse monoclonal antibody binding to a special epitope on the hepatitis B surface （HBsAg）.129G1 mAb can suppress the levels of HBsAg and HBV DNA in vivo profoundly and persistently,thus has the potential to be used in drugs of therapeutic antibodies.In order to reduce the immunogenicity of 129G1 mAb,we accomplished the humanization of 129G1 using complementarity determining region （CDR）-grafting and framework region optimization to keep the original biological function with phage display technology. 129G1 humanized antibodies＇ binding activity with HBsAg is similar to 129G1 cAb.It makes the phagocytosis rate of THP-1 ceils up to 50% at concentration of 1.45 μg/mL.In HBV transgenic mice,the humanized 129G1 exhibited continuous ability in suppressing the HBV DNA in serum and clearing HBsAg.