目的 建立降低抗体依赖性增强(antibody-dependent enhancement，ADE)效应的抗体表达系统，以期降低目标抗体的ADE效应。 方法 对哺乳细胞抗体表达载体Fc区进行L234A和L235A点突变，建立抗体表达载体pFRT-IgG1κ-FcM。选取前期工作中获得的1株具有显著ADE效应的抗体Wt-WNV利用pFRT-IgG1κ-FcM系统进行表达，获得突变后抗体FcM-WNV。ELISA检测FcM-WNV与靶抗原西尼罗病毒包膜蛋白DⅢ(West Nile virus envelope protein-DⅢ，WNV E-DⅢ)的结合，流式细胞术分析FcM-WNV与人高亲和力IgG Fc受体hFcγRⅠ(hCD64)的结合。假病毒感染宿主细胞(BHK21和K562)试验检测FcM-WNV的体外中和活性。 结果 FcM-WNV与Wt-WNV表达水平相当，能识别结合WNV E-DⅢ，且呈浓度依赖效应；与Wt-WNV相比，FcM-WNV与hCD64的结合力明显减弱，表现为荧光强度明显降低；与前期实验结果一致，Wt-WNV在5 μg/ml的浓度下具有明显增强WNV假病毒感染K562细胞的作用，而FcM-WNV在5 μg/ml浓度下，能有效阻断假病毒感染K562和BHK21细胞。 结论 本研究建立的抗体表达系统可有效降低目标抗体的ADE效应。 Objective To establish an antibody expression system to reduce the antibody-dependent enhancement (ADE) effect of target antibody. Methods Site-directed mutagenesis was used to mutate the 234 and 235 sites of the Fc region of the mammalian cell antibody expression vector-L234A and L235A to establish the antibody expression vector pFRT-IgG1κ-FcM. An antibody Wt-WNV with significant ADE effect obtained in previous work was selected and expressed by the pFRT-IgG1κ-FcM system to obtain mutant antibody FcM-WNV. The binding ability of FcM-WNV to target antigen West Nile virus envelope protein-DⅢ (WNV E-DⅢ) was detected by ELISA, and the its binding ability to human high-affinity IgG Fc receptor hFcγRⅠ (hCD64 ) was analyzed by flow cytometry. The neutralizing activity of FcM-WNVin vitro was detected by pseudovirus infection of host cells (BHK21 and K562). Results The expression levels of FcM-WNV and Wt-WNV were comparable, and FcM-WNV could recognize and bind to WNVE-DIII in a concentration-dependent manner. Compared with Wt-WNV, the binding ability of FcM-WNV to hCD64 was significantly weakened, showing a significant decrease in fluorescence intensity. Consistent with the previous experimental results, Wt-WNV at a concentration of 5 μg/ml significantly enhanced the infection of K562 by WNV pseudovirus, while FcM-WNV at a concentration of 5 μg/ml could effectively block pseudovirus infection in both K562 and BHK21 cells. Conclusions The established antibody expression system can effectively reduce the ADE effect of the target antibody.
Expression andin vitro activity of a neutralizing antibody against West Nile virus that reduces antibody-dependent enhancement
Objective To establish an antibody expression system to reduce the antibody-dependent enhancement (ADE) effect of target antibody. Methods Site-directed mutagenesis was used to mutate the 234 and 235 sites of the Fc region of the mammalian cell antibody expression vector-L234A and L235A to establish the antibody expression vector pFRT-IgG1κ-FcM. An antibody Wt-WNV with significant ADE effect obtained in previous work was selected and expressed by the pFRT-IgG1κ-FcM system to obtain mutant antibody FcM-WNV. The binding ability of FcM-WNV to target antigen West Nile virus envelope protein-DⅢ (WNV E-DⅢ) was detected by ELISA, and the its binding ability to human high-affinity IgG Fc receptor hFcγRⅠ (hCD64 ) was analyzed by flow cytometry. The neutralizing activity of FcM-WNVin vitro was detected by pseudovirus infection of host cells (BHK21 and K562). Results The expression levels of FcM-WNV and Wt-WNV were comparable, and FcM-WNV could recognize and bind to WNVE-DIII in a concentration-dependent manner. Compared with Wt-WNV, the binding ability of FcM-WNV to hCD64 was significantly weakened, showing a significant decrease in fluorescence intensity. Consistent with the previous experimental results, Wt-WNV at a concentration of 5 μg/ml significantly enhanced the infection of K562 by WNV pseudovirus, while FcM-WNV at a concentration of 5 μg/ml could effectively block pseudovirus infection in both K562 and BHK21 cells. Conclusions The established antibody expression system can effectively reduce the ADE effect of the target antibody.
Neutralizing antibodyWest Nile virusAntibody-dependent enhancement effect
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