E484K. Behind this code name, a mutation carried by variants of Covid-19 that have emerged in South Africa and, more recently, in Brazil and Japan. “The most disturbing of all” in terms of the immune response, says Ravi Gupta, professor of microbiology at the University of Cambridge.
These variants are different versions of the original coronavirus, which appear over time as a result of various mutations. This is a completely normal phenomenon in the life of a virus, because mutations occur when it replicates.
Numerous mutations of Sars-CoV-2 have been observed since its appearance, the vast majority without consequence. However, some may give it an advantage for its survival, including greater transmissibility.
The variants that have emerged in England, South Africa and Japan (the latter via travelers from Brazil) share a mutation called N501Y. Located on the coronavirus spike protein (a spike that allows it to enter cells), this mutation is suspected of making these variants more contagious.
But suspicions of a different nature weigh on the E484K mutation.
Laboratory tests have indeed shown that the E484K mutation seemed capable of reducing the recognition of the virus by antibodies, and therefore its neutralization.
“As such, it can help the virus bypass the immune protection conferred by a previous infection or by vaccination”, explains Professor François Balloux, from University College London, quoted by the British organization Science Media Center.
It’s that perspective “Immune escape” which worries scientists, with the question of the effectiveness of vaccines in their sights.
On January 8, BioNTech and Pfizer, makers of the world’s leading vaccine, assured that it was effective against the N501Y mutation. But their lab checks did not focus on E484K. They are therefore not sufficient to conclude that the efficacy of the vaccine will be the same against the variants which carry it as against the classical virus.
In addition, a study published on January 6 describes the case of a Brazilian woman sick with Covid in May, then reinfected in October by a variant carrying the E484K mutation. This second infection, more severe than the first, could be a sign that the mutation caused a poorer immune response in the patient.
However, there is no indication that E484K is sufficient to make variants resistant to current vaccines, scientists say.
The “beginning of the problems”
Even if the E484K variant appears to be less well recognized by antibodies, other components of the variants will in principle remain within their reach.
“Even if you decrease in efficiency, you will normally still have neutralization of the virus”, says Vincent Enouf, from the National Reference Center for Respiratory Viruses at the Institut Pasteur in Paris.
“I don’t think that this mutation alone is problematic for vaccines”, adds immunologist Rino Rappuoli, researcher and scientific manager of pharmaceutical giant GlaxoSmithKline (GSK), interviewed by ..
This expert co-signed a study made public on December 28. Its objective was to observe in the laboratory the emergence of a variant, by placing the virus in the presence of the plasma of a patient cured of Covid for several weeks.
After less than three months, an antibody resistant variant appeared. He carried three mutations, including E484K. “We must develop vaccines and antibodies capable of controlling emerging variants”, this study concludes.
The E484K mutation “Could be the beginning of the problems” for vaccines, judge for his part Professor Gupta. “At this stage, they should all remain effective, but what worries us is the prospect of future changes that would be added” to those we are already seeing, he explains, calling for “Vaccinate as quickly as possible everywhere in the world”.
Faced with the emergence of new variants, several laboratories have ensured that they were able to quickly provide new versions of their vaccine if necessary.