A mutation that caused the novel coronavirus to be more infectious might also have left it more vulnerable to vaccines, according to a new study.
In a new paper, published ahead of peer review, a group of scientists suggest that a mutation in the virus early on helped it to spread more efficiently.
The mutation, called D614G, occurred in the virus’ “spike protein” — which is what the virus uses to bind itself to the cell it’s attacking. Worldwide transmission patterns suggest that this mutation enabled the virus to infect people more easily, the paper’s authors write. The mutation is also associated with a higher virus load in people’s respiratory secretions.
The mutation increased the number of “spikes” on the coronavirus — which is the part that gives it its distinctive shape. Those spikes are what allows the virus to bind to and infect cells.
Most potential vaccines, the authors write, are modelled upon an earlier version of the virus, which is why they wanted to investigate whether they might work in the D614G variant too, since that mutation has since become the dominant version worldwide.
Using samples from mice, primates and humans, they found that if anything, the antibody response is bigger in the new virus than the old one.
“The gain in infectivity provided by D614G came at the cost of making the virus more vulnerable to neutralizing antibodies,” wrote the authors.
This was a lab-based study only, which used animal models, so its findings aren’t necessarily representative of real-world conditions. Still, the authors write, their findings “alleviate a major concern” in the development of a coronavirus vaccine.
Understanding how viruses mutate is vital to the hunt for a vaccine, University of Toronto epidemiologist Colin Furness previously told Global News.
“The reason why mutations are important is that both vaccines and your immune system recognize a virus by its outside, its coat,” he explained.
“So if the virus mutates in a way that changes the coat, it may well be that the immune system stops recognizing it — which we have with the flu every year — and it can also mean vaccines will fail to be effective for exactly the same reason.”
So far, World Health Organization experts said in June, the virus does not appear to have mutated significantly, which is good news.
“Scientists are looking to see: are there changes in the virus? And as it is a coronavirus — it is an RNA virus — there are normal changes in this virus that one would expect over time,” WHO infectious disease epidemiologist Dr. Maria Van Kerkhove said at a press conference.
“None of these changes so far indicate that the virus itself is changing in terms of its ability to transmit or to cause more severe disease.”
According to the World Health Organization, there are currently 25 vaccine candidates in clinical evaluation. Five are in Phase 3 trials, meaning large tests on humans.
— with files from Laura Hensley, Global News, and Reuters