Antibodies isolated from Covid-19 patients may suppress virus, study suggests

Researchers have isolated antibodies from Covid-19 patients which they say are among the most potent in neutralising coronavirus.

These antibodies could be produced in large quantities by pharmaceutical companies to treat patients, especially early in the course of infection.

They can also be used to prevent infection, particularly in the elderly, the scientists say.

The study, published in Nature, reports that researchers have confirmed the purified, strongly neutralising antibodies provide significant protection from SARS-CoV-2 infection in hamsters.

David Ho, scientific director of the Aaron Diamond Aids Research Centre and professor of medicine at Columbia University Vagelos College of Physicians and Surgeons, directed the study.

He said: “We now have a collection of antibodies that’s more potent and diverse compared to other antibodies that have been found so far, and they are ready to be developed into treatments.”

The immune system’s response to infection is to produce antibodies when it identifies substances in the body as alien, such as bacteria, viruses, and foreign substances in the blood.

While a number of drugs and vaccines in development for Covid-19 are in clinical trials, they may not be ready for several months.

So the researchers say that in the meantime, SARS-CoV-2 neutralising antibodies produced by Covid-19 patients could be used to treat other patients or even prevent infection in people exposed to the virus.

The development and approval of antibodies for use as a treatment usually takes less time than conventional drugs.

The study found that in the patients they studied, those with severe disease requiring mechanical ventilation produced the most potently neutralising antibodies.

Prof Ho said: “We think that the sicker patients saw more virus and for a longer period of time, which allowed their immune system to mount a more robust response.

“This is similar to what we have learned from the HIV experience.”

The research team found a more diverse variety of antibodies than previous efforts, including new, unique antibodies that were not reported earlier.

Prof Ho said: “These findings show which sites on the viral spike are most vulnerable.

“Using a cocktail of different antibodies that are directed to different sites in spike will help prevent the virus becoming resistant to the treatment.

“We discovered that these powerful antibodies are not too difficult for the immune system to generate. This bodes well for vaccine development.

“Vaccines that elicit strong neutralising antibodies should provide robust protection against the virus.”

The scientists say their research suggests people with severe disease are more likely to have a durable antibody response, however more research needs to be done to answer the critical question about how long immunity will last.

But they caution that although informative for researchers developing vaccines and antiviral therapies, the findings are early-stage preclinical results and the antibodies are not yet ready for use in people.

Forty patients who had tested positive for coronavirus were enrolled in a cohort study on virus-neutralising antibodies.

Plasma samples from all of them were first tested for neutralising activity against the virus, and saw a widely varying range of neutralising antibodies.

Five patients were focused on because their plasma virus-neutralising titers were among the highest.

Further studies in other animals and people are being planned.