A genetic mutation is a permanent change in the DNA sequence. It could occur due to environmental factors or due to an error that occurs during DNA replication.
‘D614G is the mutated form of SARS-CoV-2 that is 10 times more infectious than the original strain. D614G is a mutation that occurs in the spike protein. It may not have an impact on vaccine development.’
SARS-CoV-2 has undergone multiple mutations. However, only D614G mutation has so far been singled out. D614G is a mutation of SARS-CoV-2 that causes the disease COVID-19.
D614G is a mutation that occurs in the protein which makes up the virus’s spike. The virus uses this spike protein to break into our cells.
The mutation results in a change in the amino acid at position 614. Aspartic Acid (D) is changed to Glycine (G). Hence the name D614G.
Glycine is a non-polar amino acid with a side chain of a single hydrogen atom. Whereas, aspartic acid is a polar amino acid with an acidic side chain.
The difference in the basic nature of the amino acids may have significant biological implications.
The mutation is believed to have surfaced after the initial Wuhan outbreak, probably in Italy.
In July, according to the BCC report, around 97% of the samples around the world had the mutated D614G strain of coronavirus.
Dominance of D614G Variant
D614G variant of SARS-CoV-2 appears to be the dominant strain, according to Dr. Bette Korber, a computational biologist and population geneticist.
Dr. Korber suggests that the dominance of D614G strain indicates that it may spread faster between people than the original strain.
The new mutant variant took over the original strain whenever the two versions were in circulation.
Dr. Korber’s research paper suggests that the D614G is now the pandemic as the strain is so dominant. The strain has been dominant for some time, even since the start of the pandemic in places such as the UK and the east coast of the US.
Transmission of D614G Variant of Coronavirus
Lab tests conducted by Scripps University in Florida found that the mutated virus was able to enter human cells more efficiently than the original strain.
The mutation in the spike protein results in the virus sticking together better and functioning more efficiently in latching on to human cells.
New York Genome Center and New York University conducted another study and found that the mutated virus could be more transmissible compared to the original strain.
They believed that the transmissibility increased at least in the lab. They were unclear how representative the lab results are of transmission in patients.
WHO Collaborating Center in China and Dr.Korber suggested similar outcomes that the D614G is 10-fold more infectious than the original strain.
A new research review by Dr. Nathan D Grubaugh also suggested increased transmissibility but did not prove it.
Scientists also show that people infected with the mutated strain have a higher viral RNA load in the upper respiratory tract. However, the mutation is not associated with increased disease severity.
Impact of D614G strain in Vaccine Research
It was speculated earlier, that separate vaccines needed to be developed for different variants of SARS-CoV-2.
Most vaccines that are in development target a different region of the spike protein, so the mutation should have an impact on the vaccine development.
D614 mutation happens in the spike protein, but it does not change the receptor-binding domain (RBD), which is at the tip of the spike protein.
The receptor-binding domain of the virus bind to the ACE2 receptor on human cells. Thus, D614G mutation alters the spike protein but does not change the critical RBD immunogenic part.
Detection of D614G Strain in Malaysia
The mutated strain has been detected in three cases from a cluster which began when a permanent resident of Malaysia and a restaurant owner returned to the country from India.
The man breached the 14-day mandatory self-quarantine at home. He has been sentenced to five months in prison and fined.
The mutated strain was also found in another cluster which involves people returning from the Philippines.
In summary, D614G is more infectious, deadly, and transmissible than the original Wuhan-1 strain of SARS-CoV-2.