- 18 Oct 2020
After the Malaysian health officials detected a new D614G-type mutation of covid-19 in the country. The strain has sparked a panic in the world that has already been severely battling with Covid-19, especially when vaccines are showing promising results. The worrying part is it's 10 times more infectious. So, do these mutations actually matter?
What is D614G?
Sars-cov-2 has undergone several mutationsafter it recorded the first cluster of cases in Wuhan. The genome of the virus has changed hundreds of times since January but the researchers are worried about only one particular kind of mutation. That is D614G.
Due to this mutation there is a shift in the frequency of Amino acid and the spike protein at position 614 from D (Aspartic acid) to G (glycine).
[Image Source: Tracking Changes in SARS-CoV-2 Spike - Sheffield COVID-19 Genomics Group]
The G strain started its journey from Europe in late February and by the end of March it became the most common form of mutation globally. These mutations are itself mundane, because every virus mutates. The novel coronavirus is a RNA virus, the genetic material is packed inside the protein shell i.e., RNA viruses like measles and flu are more likely to change and mutate compared to DNA viruses like smallpox, herpes etc.
10 times more infectious
The Health chief of Malaysia Noor Hisham Abdullaah in a Facebook post on Sunday, 16 August said that they found three mutation cases out of 45 in a cluster that started from some person who travelled from India and breached his 14-day home quarantine.
Abdullah further said that finding this mutation which is 10 times more infectious would mean that the existing vaccine study shouldn't be included. As they might not be effective on this mutation. However, a paper published in Cell Press trashed Abdulla’s claims, saying that the mutation is unlikely to have a major impact on the efficacy of vaccines currently being developed.
Does mutation worry vaccine development?
From late January when the virus genome was sequenced, scientists have been looking for meaningful changes in variants. There were a lot of concerns about developing different vaccines for different variants. As per the scientists at the IMB Cambridge Scientific Center, The highly prevalent [G614] variant in the European population may cause antigenic drift, resulting in vaccine mismatches that offer little protection to that group of patients.
The D614G mutation happens in the Crown like viral spike protein, but the tip of the spike protein which has Receptor-binding domain (RBD) (see figure 2) doesn't change.The RBD attaches to a receptor on the respiratory cell called ACE2. In simple words, the mutation in the protein allows SARS-CoV-2 to enter cells and makes it easier for the virus to spread i.e. this results in the change in the structure of spike protein, but not the crucial RBD which is the immunogenic part. The good news however is that a vaccine with variants may work against this mutation, according to the Scripps researchers.
More infectious but less deadly
Paul Tambyah, senior consultant at the National University of Singapore and president-elect of the International Society of Infectious Diseases, said that the proliferation of the D614G mutation in some parts of the world has coincided with a drop in death rates, giving an indication that it is less lethal. "Maybe that’s a good thing to have a virus that is more infectious but less deadly,” Tambyah told Reuters. "The mutant affects the binding of the spike protein and not necessarily the recognition of the protein by the immune system, which would be primed by a vaccine," he added.
Many experts believe that this strain seems to be more infectious in laboratory setting. Though the picture is unclear in the human to human transmission and its behavior. The vaccines that are being tested right now are more likely to work against all versions of the viruses. So, this virus mutation may not be a big deal as it is made out to be. There is nothing to be scared of D614G though it is infectious it is not as deadlier.