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A*STAR researchers have identified antibodies against SARS-CoV-1 spike protein that could also bind to SARS-CoV-2.

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A spike of hope for COVID-19 detection

18 Sep 2020

Antibodies that recognize the SARS-CoV-2 spike protein show potential for diagnosing COVID-19.

Though a recent entrant into our daily vocabulary, the word ‘coronavirus’ was first coined in 1968 to describe a family of viruses, so named because the viruses were surrounded by a ‘crown’ of spiky protein projections.

As it turns out, these spikes give coronaviruses more than just their crown-like shape and name: they are also the key to their infectious ability. Each coronavirus spike contains a receptor-binding domain which binds to a specific target protein on host cells so that the virus can enter and infect them.

Interestingly, the spike of SARS-CoV-1, the virus responsible for the severe acute respiratory syndrome (SARS) epidemic in 2003, has some similarity to the spike of SARS-CoV-2, the virus responsible for the current COVID-19 pandemic. They both also share the same target: a protein on host cells called angiotensin-converting enzyme 2.

With this knowledge, a team of researchers led by Yee-Joo Tan, a Principal Investigator at A*STAR’s Institute of Molecular and Cell Biology (IMCB), decided to see if SARS-CoV-1 monoclonal antibodies (mAbs) could cross-react with SARS-CoV-2, in the hope that the same antibodies may be applied in COVID-19 research.

Using a range of immunological and bioinformatics analyses, they discovered that four monoclonal antibodies they previously generated and reported in a 2006 study to react to a section of the SARS-CoV-1 spike protein are able to recognize and cross-react with SARS-CoV-2 as well.

“SARS-CoV-1 and SARS-CoV-2 have a similar protein known as viral surface spike glycoprotein (S protein), which is responsible for binding to the host cell. 77.8 percent of the amino acid sequences in the S protein of these two viruses are identical,” Tan explained. “These antibodies bind to a part of the spike that is the same in both viruses.”

One of the antibodies, mAb 1A9, was shown to be able to detect purified S protein in a sandwich ELISA assay, as well as SARS-CoV-2-infected cells 24 hours after infection. The findings are an encouraging testament to the antibodies’ potential as a diagnostic tool, but the team noted that there is still a need to determine if the antibodies are sensitive enough to detect SARS-CoV-2 in clinical settings.

“We are working with industry partners to see if mAb 1A9 can be incorporated into COVID-19 diagnostic kits,” said Tan, adding that an antibody-based approach would complement existing PCR-based detection methods.

The A*STAR-affiliated researchers contributing to this research are from the Institute of Molecular and Cell Biology (IMCB) and the Bioinformatics Institute (BII).

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References

Zheng, Z., Monteil V.M., Maurer-Stroh, S., Chow, W.Y., Leong, C., et al. Monoclonal antibodies for the S2 subunit of spike of SARS-CoV cross-react with the newly-emerged SARS-CoV-2. Euro Surveill. 25(28) (2020) | article

About the Researcher

Yee Joo Tan

Principal Investigator

Institute of Molecular and Cell Biology
Yee Joo Tan obtained a PhD degree from the University of Cambridge in 1997. She joined the A*STAR Institute of Molecular and Cell Biology (IMCB) as a postdoctoral research fellow and is now a Principal Investigator (joint appointment) and group leader of the Monoclonal Antibody Unit. Tan concurrently holds an Associate Professor position at the Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University Health System (NUHS), National University of Singapore (NUS).

This article was made for A*STAR Research by Wildtype Media Group