new variants defeat monoclonal antibodies

Yet another wave sweeping across Europe. Drugs, monoclonal antibodies, which are running out trying to follow, in vain, the new variants that the virus keeps forging against us. Vaccines which also lose effectiveness as these new variants rise to the front. In short, the fight between the 7.9 billion humans and the microbe responsible for Covid-19, SARS-CoV-2, has become bogged down in trench warfare.

In fact, most of the monoclonal antibodies developed against certain strains of the virus saw their effectiveness vanish against the variants that followed. Result: the most vulnerable people fear finding themselves “in a therapeutic impasse”, says Yvanie Caillé, founder of the Renaloo association, which brings together patients with kidney disease. Patients suffering from severe immunosuppression (transplant patients, dialysis patients, suffering from cancer or autoimmune diseases, etc.), in particular, are at very high risk of severe forms of Covid-19; they often respond poorly to vaccination and have a dwindling therapeutic arsenal; in case of contamination, their mortality is high.

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One of the keys to the success of SARS-CoV-2: it arms itself with new mutations which distort the main target recognized by these antibodies, the Spike protein (spike) which bristles on its surface. From then on, SARS-CoV-2 passed under the radar of antibodies, rendered inoperative.

“It’s a shallot racenotes Etienne Decroly, virologist at the CNRS at the University of Aix-Marseille. For two years, all new variants of SARS-CoV-2 have tended to escape [partiellement ou complètement] to neutralizing antibodies. » This, whether it is antibodies induced by vaccination, by a natural infection or developed by drug manufacturers. No reason for it to stop: “It is the natural process of evolution, which favors the selection of variants that have acquired an advantage allowing them to propagate. »

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Partial loss of activity for Evusheld

The BA.4 and BA.5 variants of Omicron, now the majority in France, are no exception to the rule. “The arsenal of antibodies still capable of neutralizing them is dwindlingnotes Professor Olivier Schwartz, head of the virus and immunity unit at the Institut Pasteur in Paris. A whole series of antibodies have lost their effectiveness against BA.4 and BA.5 and have been withdrawn from the market. » The fault, in particular, of a new mutation, called “F486”, acquired by these two sub-variants in the Spike protein.

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