I’d say meet coronavirus but I think we’re all a bit too familiar at this point!
Coronaviruses are spherical, enveloped particles that vary between 80 and 120nm in diameter and carry an RNA genome (26.4 to 31.7kb).
The name “coronavirus” is derived from Latin – corona – meaning “crown”.
The viral envelope is made of a lipid bilayer and contains 3 different anchored proteins – the envelope (E) protein, the spike (S) protein, and the membrane (M) protein. The ratio of these proteins throughout the envelope is 1:20:300 (E:S:M). M is the main structural protein, to keep the shape and size of the particle. E is also structural but plays a role in trafficking the virus through the cell cytoplasm to the nucleus as well. Finally, S is pivotal for interaction with the host cell and is also highly immunogenic (meaning your body recognizes it quickly and mounts a robust response).
Inside the envelope there is the nucleocapsid that is made up of many small nucleocapsid (N) proteins that “bead” the RNA genome. This protein is also highly immunogenic but as it is internal, it is only expressed to your immune system after it has infected a cell, not before.
Coronaviruses cause respiratory tract infections in humans, and depending on the variety, the disease can range from mild to lethal. SARS refers to severe acute respiratory syndrome and the first coronavirus discovered to cause this was SARS-CoV-1 which caused the 2002-2004 outbreak. SARS-CoV-2 is another strain of coronavirus that also causes severe respiratory tract infections and was discovered in December 2019. It was labeled COVID-19 (coronavirus disease 2019) and was declared cause of a pandemic in March 2020.
Currently there is no “cure” to coronaviruses, but a lot has been learned about managing severe cases. Several monoclonal antibody-based therapies and anti-virals have been (and continue to be) investigated. There are also dozens of vaccines in different stages of approval/development, with 3 approved for EUA in the U.S.!
Posted on Instagram on March 4, 2021.