Researchers have identified a powerful cocktail of antibodies that can help doctors treat Covid-19 infections and protect people at risk of getting sick with the disease.
The antibodies were collected from hospitalized patients with severe Covid-19, and pharmaceutical companies could manufacture them on a scale and transfuse them into the blood to fight the virus or prevent it from taking root.
Scientists at Columbia University in New York analyzed the antibodies of 40 Covid-19 patients and identified 61 types of five individuals that effectively removed the coronavirus. Among them were nine that displayed “exquisite potency” to neutralize the pathogen.
Tests on the cells showed that the antibodies killed the virus, while experiments with hamsters revealed that an infusion of one of the most potent antibodies protected animals from the disease. “It completely killed off the infectious virus in the lung tissue of the hamsters we treated,” said David Ho, a Columbia professor of medicine who led the research.
“We specifically isolate very powerful antibodies that can be mass produced and then administered,” Ho said. “We would assume that these could be used to prevent or treat Sars-Cov-2. We would be trying to treat early in the course of the infection, particularly those at risk of developing serious illnesses such as the elderly and those with underlying illnesses. “
He added: “In terms of prevention, these could certainly replace vaccines, and again we would be looking at the most vulnerable, for example, nursing home residents.”
Efforts are underway to develop vaccines for the coronavirus, but there is uncertainty about how effective a vaccine will be and how long the protection it provides will last. Immune responses tend to be weaker in older people, so even if vaccines are available next year, infusions of synthetic antibodies that protect for months at a time would still be valuable.
Antibodies are one of the body’s main lines of defense against viral infections. When a virus invades cells and multiplies, the immune system learns to recognize the intruder and produces antibodies to deactivate the microbe. Antibodies attack from different angles and attach to the proteins from which the virus is made.
Pharmaceutical companies already manufacture synthetic antibodies in bulk, purifying them from cells that grow in large fermenters. Estimates suggest that an antibody dose could cost $ 50 (£ 39) to produce, Ho said.
Work is underway to test all the antibodies in animals, but the researchers hope to synthesize enough to launch a phase 1 safety test in humans in October. If the trial determines that transfusions are safe, efficacy trials could start early next year, Ho said. Antibodies can be designed to persist in the blood for three to six months.
Writing in the journal Nature, scientists describe how most of the antibodies bind to the “spike” proteins that line the virus’s surface. These create the crown from which the virus takes its name. Some of the most potent antibodies defeated the virus by binding to the spike protein in such a way that it could no longer invade human cells.
Transfusions of blood plasma containing antibodies from recovered Covid-19 patients suggest that they may help patients when administered before the virus causes catastrophic damage. But Ho’s anticipated synthetic cocktails are expected to be more effective because they can be designed to contain high levels of the more potent antibodies.
The antibody combination is so diverse that researchers believe it will be difficult for mutated variants of the virus to evade them. “Using a cocktail of different antibodies that target different sites on the spike will help prevent the virus from becoming resistant to treatment,” Ho said.
