Among the many variants of SARS-CoV-2 currently circulating in the world, there is one that particularly worries scientists: the South African variant. More contagious, it would also resist vaccines.
A variant resistant to neutralizing antibodies
At a time when many hospital systems around the world are on the verge of collapse due to the pandemic, the new, more contagious variants detected in the UK (called B.1.1.7) in South Africa (said 50.1. Y.V2 or B.1.351) and in Brazil (referred to as P1), are causing increasing concern. These three variants have a common characteristic: the N501 mutation, responsible for the outbreak of new cases of contamination observed in these countries. While several studies have shown that the mRNA vaccines developed by Pfizer / BioNTech and Moderna remain effective on the British variant, nothing is less certain for their African and Brazilian counterparts. Indeed, the vaccine would be effective on the N501Y mutation, common to the three variants, located on the Spike protein of the coronavirus which corresponds to its end and which allows it to attach to human cells and to infect them.
Adapt vaccines to this new strain
On the other hand, another mutation, called E484K, which is also located on the Spike protein, would only concern the South African and Brazilian variants. Scientists have already shown that this mutation is less well recognized by antibodies, and therefore more resistant to vaccines. According to a study by South African researchers, posted online Wednesday, the South African variant “is largely resistant to neutralizing antibodies caused in response to infection by previously circulating strains”. In other words, the risk of infection or reinfection by this variant is high, the study says. The authors of the study call for identifying new targets that would be less subject to modifications than the Spike protein, so as to be able to adapt the strains used in vaccines.
