Table 1. Study on prevention and treatment of nano-antibody in COVID-19
The origin of nano-antibody:
Nano-nano-body (Nbs) was first reported by Belgian scientist Hamers-Casterman and his team in 1993 in the journal Nature. It was found that some antibodies in the blood of camels (camels, alpacas and their close relatives) are "heavy chain antibodies" lacking light chains, and only contain one heavy chain variable region (VHH) and two heavy chain CH 2 and CH 3 regions (CH2 and CH3). VHH retains all the antigen binding ability and is the smallest complete antigen binding fragment, which is called single domain antibody. VHH crystal is 2.5 nm and 4 nm long, and its molecular weight is only 15 kDa.
Figure 1. Schematic diagram of conventional antibodies and nano-antibodies.
Advantages of nano-antibody over traditional antibody;
Compared with traditional antibodies, nano-antibodies also have the advantages of simple humanization, high affinity, high stability, microbial expression, low immunogenicity, good solubility, strong penetration and recognition of hidden epitopes. The unique physical and chemical stability of nano-antibodies provides a new research tool for diagnosis and treatment. More and more attention has been paid to the research and development of antibody drugs, basic medical research and disease diagnosis and treatment.
Nano-antibody drugs approved for global marketing:
In 20 18, the European union approved-the world's first nano-antibody drug Caplacizumab for treating adult acquired thrombotic thrombocytopenic purpura, which prevents coagulation by blocking the interaction between oversized vWF polymer and platelets. In 20021year, PD-L 1 Antibody Envida, jointly developed by Corning Jerry Pharmaceutical, Sildi Pharmaceutical and Voice, was approved for listing in China, which was the first nano-antibody drug approved for listing in China. At present, many nano-antibody drugs are in the clinical trial stage (Table 2).
Table 2. Nano-antibody drugs in clinical stage
Preparation process of nano-antibody;
The preparation process of nano-antibody mainly includes preparation of target antigen, immunization of alpaca, preparation of antibody library, screening of high affinity antibody, expression of recombinant antibody and functional identification of antibody activity analysis (Figure 2).
Figure 2. Preparation technology of nano-antibody.
Application of nano-antibody;
1. Disease diagnosis: molecular imaging, tumor diagnosis, image-guided surgery.
2. Cell therapy: targeted radiotherapy, chemotherapy drug delivery, immunotherapy.
3. Research and development of antibody drugs: finding targets → designing drugs → biological trials → clinical trials → approval for marketing.
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Editor: Zhang Taotao