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Exploiting similarities between SARS-CoV-2 and other viruses to accelerate vaccine and therapy development
Posted on April 17th, 2020 by Paul Dockerty in COVID-19
Coronavirus disease 19 (COVID-19) is now present in 230 countries, areas or territories around the world. As of April 15, 2020, the World Health Organization has reported 117,021 deaths . Researchers across the globe are collaborating to develop antivirals and vaccines. In this context, understanding the vast amount of data published on SARS-CoV and other viruses is key to tackling the challenge of containing the 2019 novel coronavirus (SARS-CoV-2).
Genetic and phenotypic similarities between SARS-CoV-2 and other known viruses can highlight research areas worth pursuing. Here I’d like to discuss three examples:
- The main proteases of the original SARS-CoV and SARS-CoV-2 show striking similarities and drugs targeting the protease of the first could be effective against the second
- By the same token, feature similarities between the SARS-CoV main protease and the 3C proteases of enteroviruses could be exploited as effective drug target sites
- Finally, overlap in binding sites of antibodies studied for SARS-CoV may point to effective vaccines for the current pandemic
These comparisons based on knowledge about known viruses require data that have been normalized across sources, which is a key feature of Reaxys Medicinal Chemistry (RMC) data on substance pharmacokinetics, toxicity, safety, metabolic profile and target affinity. Thus, a few weeks ago we identified 393 substances in RMC that interact with 25 targets related to six target species and coronavirus groups (SARS-CoV, Middle East respiratory syndrome [MERS] coronavirus, human coronavirus 229E, Coronaviridae, and Coronavirinae) with an affinity of <1 mM.
The list included substances containing characteristic covalent warheads such as α-ketoamide, Michael acceptors or aldehydes that, given the possibly high similarity between SARS-CoV and SARS-CoV-2, were likely to be potent binders of the SARS-CoV-2 main protease. This possibility was confirmed on March 20, 2020 in a Science publication  showing the X-ray structures of the unliganded protease SARS-CoV-2 Mpro (which shares 96% sequence identity with SARS-CoV Mpro) and its complex with an α-ketoamide inhibitor. The inhibitor showed lung tropism in mice and could be nebulized for direct administration to the lungs where the virus thrives.
Similarities between coronaviruses and enteroviruses are also insightful. The main protease of coronaviruses and the 3C protease of enteroviruses have a similar active site. I used RMC to quickly generate a list of 148 substances that interact with enterovirus 3C proteases. Among the most potent inhibitors in the resulting list, derivatives using cyanohydrin as an anchor group quickly emerged as an intriguing option for SARS-CoV-2 Mpro  considering their demonstrated affinity and selectivity for EV71 3Cpro and SARS-CoV-Mpro. If you’re interested in seeing this list of substances, please contact me directly.
Conserved domains among viruses are particularly interesting for the structure-based design of therapeutics  and the development of vaccines. On April 3, 2020 a group from The Scripps Research Institute demonstrated that an antibody recovered from a survivor of the SARS epidemic reacts with SARS-CoV-2 . The antibody’s binding site on the two coronaviruses differs by only four amino acids. These findings can help develop treatments for COVID-19 and hint at vulnerabilities that we could exploit to fight coronaviruses in general and avoid future pandemics.
Catalyzing these types of insights was our goal in creating the Coronavirus Research Repository with 1science. Mirroring the mission of 1science to aggregate quality-controlled academic and research documents in all disciplines and languages and from all countries, and leveraging its core index 1findr with >120 million metadata records and >30 million links to free full-text articles from roughly 100,000 referred scholarly journals, the Coronavirus Research Repository is a custom extraction comprising articles on COVID-19, MERS, SARS and coronaviruses in general.
So, where do you go next?
If you would like to see the list of 148 drugs I extracted by comparing coronaviruses and enteroviruses, please contact me directly.
Finally, I am also happy to help if you need access to other datasets for your COVID-19 research, or have questions about how to pursue the insights I’ve described and take advantage of the datasets we have made available.
 WHO – Situation report 85
 L. Zhang et al., Science 10.1126/science.abb3405 (2020)
 Y. Zhai et al., 10.1021/acs.jmedchem.5b01013 (2015)
 L. Zhang et al., J. Med. Chem. 10.1021/acs.jmedchem.9b01828 (2020)
 M. Yuan et al., Science 10.1126/science.abb7269 (2020)
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