Antibody Neutralizes Covid-19, SARS Viruses

David Veesler (University of Washington)

19 May 2020. An academic-industry team discovered that an antibody produced during the 2003 SARS outbreak can neutralize similar viruses causing Covid-19 infections. Results of lab research by infectious disease biologists at University of Washington in Seattle and biotechnology company Humabs Biomed SA in Bellinzona, Switzerland appear as an early unedited manuscript in yesterday’s issue of the journal Nature.

In people who recovered from Covid-19, white blood cells in plasma contain antibodies to protect the individual from further infections from the SARS-CoV-2 virus. In some cases, those antibodies neutralize, while other antibodies stimulate a response from other immune-system cells, or simply bind to the virus without affecting its infectiousness.

Plasma with antibodies from recovered Covid-19 patients is called convalescent plasma and is considered a potential source of treatments for the disease. The Food and Drug Administration on 3 April issued updated regulatory guidance for convalescent plasma’s use in clinical trials and expanded authorized emergency access for seriously ill patients for whom clinical trials are not feasible. In the meantime, researchers and physicians are encouraging people who recovered from Covid-19 infections to donate plasma until synthetic antibodies can be designed, tested, and produced.

A team from the lab of structural biologist David Veesler at University of Washington analyzed antibodies produced by people who recovered from the severe acute respiratory syndrome, or SARS, outbreak that began in China in 2002. SARS spread initially in China and East Asia, eventually reaching North America in 2003. While SARS is also a coronavirus and transmitted from human to human, it proved not to be as contagious as Covid-19.

From their analysis, Veesler and colleagues isolated an antibody called S309 that they say is particularly potent at neutralizing both original SARS and SARS-CoV-2 viruses. Veesler’s lab studies the composition of viral proteins, particularly the way chemical components of those proteins fit together and interact. Their new study identifies vulnerabilities in the coronavirus’s spike protein that binds to cells and causes infections. And their findings show S309 blocks the spike protein from binding, thus preventing infections by SARS and SARS-CoV-2 viruses.

S309 is produced by B-cells in the immune system of people with SARS. The researchers found the natural immunity produced by S309 can be enhanced by adding other antibodies that invoke other immune system cells but not necessarily neutralize invading viruses on their own. As a result, a cocktail of responsive antibodies could be the basis for a broad-spectrum therapy or preventive vaccine against mutating SARS-Cov-2 viruses, as well as other coronaviruses sharing the same infection mechanism with spike proteins.

Humabs Biomed is a subsidiary of Vir Biotechnology Inc. in San Francisco that licenses S309 for further development. The company develops treatments for infectious diseases with a series of platforms, including synthetic antibodies that work like natural antibodies produced by people who recover from these conditions. The company’s antibodies are designed to neutralize pathogens or stimulate the immune system, or both in some cases.

For Covid-19, Vir Biotechnology is developing two synthetic antibodies as Covid-19 treatments code-named VIR-7831 and VIR-7832. Drug maker GlaxoSmithKline is collaborating with Vir Biotech on VIR-7832. As reported by Science & Enterprise on 30 March, Vir Biotech is also partnering with Generation Bio in Cambridge, Massachusetts on a gene therapy to treat Covid-19.

More from Science & Enterprise:

• Microsoft, Biotech Examine Covid-19 Immune Response
• Biotech Gains Antibody Discovery, Manufacturing Funds
• Univ Building Single Covid-19 Diagnostic, Antibody Test
• Fast, Simple Covid-19 Antibody Test Being Developed
• Covid-19 Antibody Therapy Prepares for Trial

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