By: Ayyan Shaikh
What exactly is coronavirus? How did it come into being? Does it have any history? Is there a conspiracy theory behind it or did it appear out of nowhere? It's quite shocking and appalling how something that's not even considered a proper living thing can affect human lives so much, and that too, so quickly.
So let's look at what this virus is and how and when was it first discovered.
Coronaviruses are a group of related RNA viruses that cause diseases in mammals and birds. Coronaviruses are well established pathogens of humans and animals. In humans, they can cause various diseases and infections in the respiratory tract. These infections can be mild or lethal. Mild infections can be common cold while lethal infections can be the effects of COVID-19 and others.
Coronaviruses are classified into three groups, initially based on antigenic relationships of the spike (S), membrane (M) and nucleocapsid (N) proteins and now re-enforced by viral genetic phylogeny (Box 57.1). The HCoVs 229E and NL63 are group 1 coronaviruses, while OC43, HKU-1 and SARS coronaviruses are classified in group 2. Group 3 coronaviruses are found in avian species. Genetic recombination readily occurs between members of the same and of different coronavirus groups providing opportunity for increased genetic diversity.
Coronaviruses were first discovered in 1930 when an acute respiratory infection of domesticated chickens was shown to be caused by infectious bronchitis virus. In the 1940s, two more animal coronaviruses (MHV and TGEV) were isolated. It was not realized at that time, that these three viruses were related. Human coronaviruses were, however, discovered in the 1960s. In 1965, Tyrrell and Bynoe found that they could passage a virus named B814. It was found in human embryonic tracheal organ cultures obtained from the respiratory tract of an adult with a common cold. The virus was not able to be cultivated using standard techniques which had successfully cultivated rhinoviruses, adenoviruses and other known common cold viruses. In 1965, Tyrrell and Byone successfully cultivated the novel virus by serially passing it through organ culture of human embryonic trachea.
This was the history of the coronavirus. Now let's look at the origins. The most recent common ancestor of all coronaviruses is estimated to have existed as recently as 8000 BCE, although some models place the common ancestor as far back as 55 million years or more, implying long term coevolution with bat and avian species. The large number and global range of bat and avian species that host viruses has enabled extensive evolution and dissemination of coronaviruses. Many human coronaviruses have their origins in bats. The human coronavirus NL63 shared a common ancestor with a bat coronavirus between 1190 and 1449 CE. Unlike other beta coronaviruses, bovine coronavirus of the species Betacoronavirus 1 and subgenus Embecovirus is thought to have originated in rodents and not in bats. In the 1790s equine coronavirus diverged from the bovine coronavirus after a cross species jump. Later in the 1890s, human coronavirus OC43 diverged from bovine coronavirus after another cross-species spillover event. In the 1950s, the human coronavirusOC43 began to diverge into its present genotypes.
At present, there are 2,498,731 active cases and 1,992,227 closed cases out of which there have been 301,588 deaths and 1,690,669 recoveries. Due to the increasing death rate of COVID-19, the question as to when the situation will go back to normal arises. Experts have said that, even if the number of cases start to fall in the next three months, it’ll still be far from the end. It can take a long time for the tide to go out - possibly years. It is clear that the current strategy of shutting down a large part of the society is not sustainable in the long term as the damage that would be caused, in addition to the current one, to society and the economy will be disastrous. As for now, all we can do is take precautionary measures and hope that everything will go back to normal, even though it seems far from what is likely to happen because this is a ginormous scientific, societal and economic challenge and there is, for now, no exit strategy.
(Advice: Better to be six feet apart than six feet under, amIright or amIrite?)
Sources:
[1](n.d.). Coronavirus - Wikipedia. Retrieved May 9, 2020, from https://en.wikipedia.org/wiki/Coronavirus
[2] (n.d.). Coronavirus - an overview | ScienceDirect Topics. Retrieved May 9, 2020, from https://www.sciencedirect.com/topics/neuroscience/coronavirus
[3] "Coronaviruses, a new group of animal RNA viruses. - NCBI." https://www.ncbi.nlm.nih.gov/pubmed/4316767. Accessed 9 May. 2020.
[4] "Current Topics in Microbiology and Immunology / Ergebnisse ...." https://www.springer.com/gp/book/9783642657771. Accessed 9 May. 2020.
[5] "History and Recent Advances in Coronavirus Discovery : The ...." https://journals.lww.com/pidj/fulltext/2005/11001/history_and_recent_advances_in_coronavirus.12.aspx. Accessed 9 May. 2020.
[6] "A Case for the Ancient Origin of Coronaviruses | Journal of ...." https://jvi.asm.org/content/87/12/7039. Accessed 9 May. 2020.
[7] "Molecular Evolution of Human Coronavirus Genomes ...." 19 Oct. 2016, https://europepmc.org/article/med/27743750. Accessed 9 May. 2020.
[8] "Evidence Supporting a Zoonotic Origin of Human Coronavirus ...." https://jvi.asm.org/content/86/23/12816. Accessed 9 May. 2020.
[9] "Discovery of a Novel Coronavirus, China Rattus Coronavirus ...." https://jvi.asm.org/content/89/6/3076. Accessed 9 May. 2020.
[10] "Evolutionary dynamics of bovine coronaviruses: natural ...." 26 Jun. 2013, https://www.ncbi.nlm.nih.gov/pubmed/23804565. Accessed 9 May. 2020.
[11] "Molecular Epidemiology of Human Coronavirus OC43 ... - NCBI." https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3194943/. Accessed 9 May. 2020.
[12] "Coronavirus Worldometer Sections." https://www.worldometers.info/coronavirus/. Accessed 14 May. 2020.
[13] "Coronavirus: When will the outbreak end and life get ... - BBC." 23 Mar. 2020, https://www.bbc.co.uk/news/health-51963486. Accessed 14 May. 2020.
Comments