Abstract
We report the isolation of two human IgG1k monoclonal antibodies (mAbs) directed against the SARS-CoV-2 spike protein. These mAbs were isolated from two donors who had recovered from COVID-19 infection during the first pandemic peak in the Lombardy region of Italy, the first European and initially most affected region in March 2020. We used the method of EBV immortalization of purified memory B cells and supernatant screening with a spike S1/2 assay for mAb isolation. This method allowed rapid isolation of clones, with one donor showing about 7% of clones positive against spike protein, whereas the other donor did not produce positive clones out of 91 tested. RNA was extracted from positive clones 39–47 days post-EBV infection, allowing VH and VL sequencing. The same clones were sequenced again after a further 100 days in culture, showing that no mutation had taken place during in vitro expansion. The B cell clones could be expanded in culture for more than 4 months after EBV immortalization and secreted the antibodies stably during that time, allowing to purify mg quantities of each mAb for functional assays without generating recombinant proteins. Unfortunately, neither mAb had significant neutralizing activity in a virus infection assay with several different SARS-CoV-2 isolates. The antibody sequences are made freely available.
Highlights
The COVID-19 pandemic, first detected in Wuhan in late 2019, reached Europe as well as other countries in Asia and America by January 2020
Methods include isolation from human VH-VL libraries, direct antibody sequencing from memory or antigen-specific B cells, purified from individuals post-infection or post-vaccination, expansion in vitro of B cell clones, as well as more classical monoclonal antibodies (mAbs) production from immunized animals followed by humanization [1,5]
Since our unit had previous expertise in culturing B cells, their immortalization with Epstein Barr virus (EBV) and therapeutic monoclonal antibodies, as well as the availability in-house of some of the first tests for detection of anti-SARS-CoV-2 antibodies, we set out to try and isolate new mAbs from local personnel who had recovered from COVID-19, as soon as the complete lockdown was lifted, allowing non-essential activities to be resumed
Summary
The COVID-19 pandemic, first detected in Wuhan in late 2019, reached Europe as well as other countries in Asia and America by January 2020. 8 weeks from 8 March to 4 May 2020, only life-saving clinical laboratory activities by a restricted number of staff were allowed, all other workers being strictly confined at home at all times, except to purchase food or for health issues In this context, since our unit had previous expertise in culturing B cells, their immortalization with Epstein Barr virus (EBV) and therapeutic monoclonal antibodies (mAbs), as well as the availability in-house of some of the first tests for detection of anti-SARS-CoV-2 antibodies, we set out to try and isolate new mAbs from local personnel who had recovered from COVID-19, as soon as the complete lockdown was lifted, allowing non-essential activities to be resumed. Our results are discussed in the context of mAb isolation for COVID-19 and other infectious diseases
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
