A Novel Human Antibody,HF,against HER2/erb-B2 Obtained by a Computer-Aided Antibody Design Method

Fully human antibodies have minimal immunogenicity and safety profiles.At present,most potential antibody drugs in clinical trials are humanized or fully human.Human antibodies are mostly generated using the phage display method(in vitro)or by transgenic mice(in vivo);other methods include B lymphocyte immortalization,human–human hybridoma,and single-cell polymerase chain reaction.Here,we describe a structure-based computer-aided de novo design technology for human antibody generation.Based on the complex structure of human epidermal growth factor receptor 2(HER2)/Herceptin,we first designed six short peptides targeting the potential epitope of HER2 recognized by Herceptin.Next,these peptides were set as complementarity determining regions in a suitable immunoglobulin frame,giving birth to a novel anti-HER2 antibody named "HF,"which possessed higher affinity and more effective anti-tumor activity than Herceptin.Our work offers a useful tool for the quick design and selection of novel human antibodies for basic mechanical research as well as for imaging and clinical applications in immune-related diseases,such as cancer and infectious diseases.

Binding Activity Difference of Anti-CD20 scFv-Fc Fusion Protein Derived from Variable Domain Exchange

Two novel engineered antibody fragments binding to antigen CD20 were generated by fusing a murine IgM-type anti-CD20 singie-chain Fv fragment （scFv） to the human IgG1 CH2 （i.e., Cγ2） and CH3 （i.e., Cγ3） domains with the human IgG1 hinge （i.e. Hγ）. Given the relationship between structure and function of protein, the 3-D structures of the two engineered antibody fragments were modeled using computer-aided homology modeling method. Furthermore, the relationship between 3-D conformation and their binding activity was evaluated theoretically. Due to the change of active pocket formed by CDRs, the HL23 （VH-Linker-VL-Hγ-Cγ2-Cγ3） remained its activity because of its preserved conformation, while the binding activity of the LH23 （VL-Linker-VH-Hγ-Cγ2-Cγ3） was impaired severely. Experimental studies by flow cytometry and fluorescence microscopy showed that HL23 possessed significantly superior binding activity to CD20-expressing target cells than LH23. That is to say, the order of variable regions could influence the binding activity of the fusion protein to CD20^＋ cell lines, which was in accordance with the theoretical results. The study highlights the potential relationship between the antibody binding activity and their 3-D conformation, which appears to be worthwhile in providing direction for future antibody design of recombinant antibody.

Recombinant vaccine containing an RBD-Fc fusion induced protection against SARS-CoV-2 in nonhuman primates and mice

The novel coronavirus SARS-CoV-2 has infected more than 104 million individuals and resulted in more than 2.2 million deaths worldwide as of February 7,2021(https://covid19.who.int).The COVID-19 pandemic highlights the need for safe and effective vaccines against SARS-CoV-2 infection.

Human IgG1 C_γ1 Domain Is Crucial for the Bioactivity of the Engineered Anti-CD20 Antibodies

In this study, we discussed the necessity of human IgG1 Cγ1 domain for recombinant antibody using computeraided homology modeling method and experimental studies. The heavy （VH） and light （VL） chain variable regions of 1-28, a murine IgM-type anti-CD20 mAb, were ligated by linker peptide （Gly4Ser）3 to form the single-chain Fv fragment （scFv）. Then, the engineered antibody （LH1-3） was generated by fusing scFv with the entire IgG1 heavy constant regions. The 3-D structure of LH1-3 was modeled using computer-aided homology modeling method and the binding activity of LH1-3 was evaluated theoretically. Compared to the 3-D structure of the Fv fragment of the parent antibody, the conformation of the active pocket of LH1-3 was remained because of the rigid support of Cγ1. Further experimental results of flow cytometry showed that the engineered anti-CD20 antibody possessed specifically binding activity to CD20-expressing target cells. The anti-CD20 antibody fragments could also mediate complement-dependent cytotoxicity （CDC） of human B-lymphoid cell lines. Our study highlights some interests and advantages of a methodology based on the homology modeling and analysis of molecular structural properties.