As Canadians prepare to adjust to the new reality of travel restrictions, self-imposed isolation and quarantine, many questions concerning the virus known as COVID-19 are sure to arise. In this blog, In this post, I summarize some of the basic biology of the virus. Please see the sources cited at the end of this post for more information.
Naming the virus: There are 39 species of corona viruses. They all inhabit vertebrate animals. This new corona virus commonly known as COVID 19 has been renamed as SARS-CoV-2 by the Study Group (CSG) of the International Committee on Taxonomy of Viruses. 1
Crossing the species barrier: With SARS (2002) and MERS (Middle East) a few years later, the initial animal vertebrate was a bat. The SARS virus in 2002 crossed the species barrier from a bat and then crossed again to infect civet cats and then crossed again into humans. The MERS virus crossed from a bat to a camel to humans. 2
The Viral Life Cycle: Viruses either contain DNA or RNA, inside a protein coat. Corona Viruses only have RNA. Corona Viruses attach to a cell, bind and inject their RNA into the cell. They take over the machinery of the DNA/RNA replication and make viral RNA. They then program the cell to make viral protein coats, assemble the new viruses and then the cell ruptures. The population of viruses then increases dramatically in that person.
Hope: The binding and injection of SARS in 2002 and SARS-CoV-2 (COVID 19) use the same receptor. There is an approved blocking agent successful against SARS 2002 that has potential for preventing the entry of COVID 19. If it doesn’t enter, it can’t create new viruses. That is hopeful. This general name for this type of drug is called a protease inhibitor. It is called TMPRSS2 Inhibitor. 3
Stopping It: SARS in 2002 and MERS were stopped by conventional methods that included travel restrictions, and patient isolation. Washing with soap is effective against transmission. There is some evidence that antibodies for SARS in 2002 offer some protection against SARS-CoV-2 (COVID 19) and that vaccines attenuated from Rabbit Sera were effective against viral entry. 4
Viral targets: Cells in the lung that are targeted are macrophages (immune response cells) and pneumocytes (cells that line the alveoli, where oxygen enters the blood and carbon dioxide leaves the blood). 5
Citations:
- Gorbalenya, A.E., Baker, S.C., Baric, R.S. et al. The species Severe acute respiratory syndrome-related coronavirus: classifying 2019-nCoV and naming it SARS-CoV-2. Nat Microbiol (2020). https://doi.org/10.1038/s41564-020-0695-z
- Penn Medicine News. The Biology of Coronaviruses: From the Lab to the Spotlight. https://www.pennmedicine.org/news/news-blog/2020/march/the-biology-of-coronaviruses
- Hoffmann et al., SARS-CoV-2 Cell Entry Depends on ACE2 and TMPRSS2 and Is Blocked by a ClinicallyProven Protease Inhibitor, Cell (2020), https://doi.org/10.1016/j.cell.2020.02.052
- Hoffmann et al., SARS-CoV-2 Cell Entry Depends on ACE2 and TMPRSS2 and Is Blocked by a ClinicallyProven Protease Inhibitor, Cell (2020), https://doi.org/10.1016/j.cell.2020.02.052
Thanks for sharing Dave !!