As mentioned in the Introduction, SARS-CoV-2 is a novel strain, evolved from its ancestor SARS-CoV. Of course, the novel coronavirus has many more ancestors, many of which are shown in the phylogenetic tree below, which also includes the full-length genome sequences of each coronavirus and betacoronavirus. A discussion of one specific mutation on SARS-CoV-2 itself is discussed below the following chart.
Fig. 1: Phylogenetic Tree of SARS-CoV-2, SARSr-CoVs, as well as other betacoronaviruses
Although SARS-CoV-2 has been changing sluggishly, one mutation called D614G has been spotted in the gene encoding the spike protein, which helps the virus penetrate cells. The amino acid glycine was replacing aspartate at the 614th amino acid position of the spike protein.
Using cryo-electron microscopy, a team of scientists checked to see whether this mutation changed the structure of the virus in any way. They discovered that the D614G mutation loosens the spike protein. The protein binds to receptors on host cells and in turn helps the virus enter the host cell. The spike protein is composed of three smaller peptides in either an “open” or a “closed” orientation. Having more that are open makes it easier for the spike protein to bind. The D614G mutation seems to relax connections between the peptides, which increases the chances of “open” orientations. This might in turn increase the chance of infection.
More his mutation has rapidly spread and is now a widespread part of the virus. It may also be a sign of the SARS-CoV-2 virus evolving. According to Korber and Montefiori, the D614G mutation has given the virus a more transmissible form. According to other scientists, the mutation allows SARS-CoV-2 to infect cells more easily. Some others say that the mutation may make targeting the virus with vaccines easier. As it stands, there has been no solid proof of the sort of effect that the mutation has on the virus.
“Cambridge to Spearhead £20million Alliance to Map Spread of Covid-19 Coronavirus.” University of Cambridge, 23 Mar. 2020, https://www.cam.ac.uk/research/news/cambridge-to-spearhead-ps20million-alliance-to-map-spread-of-covid-19-coronavirus.
Huang, Pien. “The Coronavirus Is Mutating. but That May Not Be a Problem for Humans.” NPR, NPR, 25 Mar. 2020, https://www.npr.org/sections/goatsandsoda/2020/03/25/820998549/the-coronavirus-is-mutating-but-that-may-not-be-a-problem-for-humans.
“The Pandemic Virus Is Slowly Mutating. but Is It Getting More Dangerous?” Science, https://www.science.org/news/2020/07/pandemic-virus-slowly-mutating-it-getting-more-dangerous.