Therapeutic Human Monoclonal Antibodies from SARS-CoV-2 Surface Protein Immunized Humanized Antibody Mice

Monoclonal antibodies are the most important type of biotechnological products after vaccines and recombinant proteins. They are the strategic commanding heights of biotechnology and biomedicine industries in the 21^st century. After 35 years of development, monoclonal antibody technology has gone through four stages: murine, chimeric, humanized, and fully human monoclonal antibodies. In response to the COVID-19 outbreak, Creative Biolabs can provide the service of immunizing humanized antibody mice with SARS-CoV-2 surface protein to screen for therapeutic human monoclonal antibodies.

Strategies to Develop Therapeutic Human Monoclonal Antibodies Against SARS-CoV-2

Currently, there are two main technical solutions for the development of therapeutic human monoclonal antibodies to COVID-19.

• Therapeutic Human Monoclonal Antibodies from COVID-19 Recovered Patient Sera

At present, some research institutions are using this technical solution. This method requires abundant clinical resources to obtain a sufficient number of B cells to select high-quality candidate antibodies. While, as the cells are isolated directly from the patient, 1-2 months of animal immunization time can be waived, so the early development will be faster, and existing research institutions have completed the screening of candidate antibodies and the construction of antibody-expressing cell lines.

• Therapeutic Human Monoclonal Antibodies from SARS-CoV-2 Surface Protein Immunized Humanized Antibody Mice

The technical system of this method is relatively mature (at present, 30 fully human monoclonal antibodies approved by the FDA and 21 are derived from humanized antibody animals), but the resources of humanized antibody animals that need to be used are relatively scarce. Taking the monoclonal antibody drug for Ebola treatment as an example, the clinical trial study of PALM2018-2019 shows that: the three monoclonal antibody mixtures REGN-EB3 derived from humanized antibody animals are used for clinical treatment of Ebola infection and the mortality rate is 33.5%. The monoclonal antibody mAb114 derived from Ebola recoverers has a clinical mortality rate of 35.1% in clinical treatment of Ebola infections.

Solutions from Creative Biolabs

Creative Biolabs is providing monoclonal antibody screening services based on humanized antibody mice. We have self-cultivated humanized antibody mice, through the immunization of the S-RBD protein antigen, a dominant protein which is on the surface of the SARS-CoV-2 and plays a crucial role in mediating virus entry into target cell, and use the hybridoma fusion protocol to conduct the discovery study of human monoclonal antibodies for COVID-19 treatment. Through hybridoma fusion combined with semi-solid screening, we have screened a certain number of hybridoma cell lines that can efficiently bind S-RBD. Through the blocking experiment of RBD protein binding to ACE2, we further selected hybridoma clones with high blocking effect and high affinity for live virus neutralization experiments, and obtained hybridomas with live virus neutralization effect. The recombinantly expressed neutralizing antibody has better affinity and neutralizing activity than other neutralizing antibodies.

Fig.1 Flow of therapeutic human monoclonal antibodies screening.

Highlight Strengths

• Proprietary humanized antibody mice model
• Mature hybridoma technology
• Leading recombinant antibody technology
• Systematically antibody discovery and evaluation workstation

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