Data_Sheet_1_Genetic Removal of the CH1 Exon Enables the Production of Heavy Chain-Only IgG in Mice.docx

Nano-antibodies possess great potential in many applications. However, they are naturally derived from heavy chain-only antibodies (HcAbs), which lack light chains and the CH1 domain, and are only found in camelids and sharks. In this study, we investigated whether the precise genetic removal of the CH1 exon of the γ1 gene enabled the production of a functional heavy chain-only IgG1 in mice. IgG1 heavy chain dimers lacking associated light chains were detected in the sera of the genetically modified mice. However, the genetic modification led to decreased expression of IgG1 but increased expression of other IgG subclasses. The genetically modified mice showed a weaker immune response to specific antigens compared with wild type mice. Using a phage-display approach, antigen-specific, single domain VH antibodies could be screened from the mice but exhibited much weaker antigen binding affinity than the conventional monoclonal antibodies. Although the strategy was only partially successful, this study confirms the feasibility of producing desirable nano-bodies with appropriate genetic modifications in mice.

纳米抗体在众多应用领域展现出巨大的潜力。然而，它们自然来源于仅含重链的抗体（HcAbs），缺乏轻链和CH1结构域，且仅存在于骆驼和鲨鱼中。在本研究中，我们探讨了精确遗传去除γ1基因的CH1外显子是否能够使小鼠产生功能性的重链仅含IgG1。在遗传改良小鼠的血清中检测到了缺乏相关轻链的重链二聚体IgG1。然而，这种遗传改良导致了IgG1表达水平的降低，而其他IgG亚类的表达水平则有所增加。与野生型小鼠相比，遗传改良小鼠对特定抗原的免疫反应较弱。利用噬菌体展示技术，从小鼠中筛选出了抗原特异性的单域VH抗体，但它们的抗原结合亲和力远低于传统单克隆抗体。尽管该策略仅部分成功，但本研究证实了在鼠标中通过适当的遗传改良生产期望的纳米抗体是可行的。