There is currently no drug to cure the new coronavirus, but scientists have found more evidence that the human immune system can develop neutralizing antibodies that can block virus-infected cells.
These antibodies can be used to develop treatments for COVID-19, including vaccines and monoclonal antibodies, which act like recovery plasma therapy.
The immune system is "trained" to produce antibodies to any pathogen that enters the body. Immune cells recognize foreign cells, label them, and eliminate them. The resulting antibodies prevent the same infectious microbes from re-infecting human cells, which is why plasma therapy works.
Now, researchers from Rockefeller University have published a study detailing the existence of a universally effective antibody.
The researchers looked at 149 patients recovering from COVID-19 and found that not all of them developed the same type of immune response. Some people don't even have the kind of strong neutralizing antibodies that inhibit the virus, but they do produce other types of antibodies.
The good news is that many people have produced strong neutralizing antibodies that bind to the S protein of COVID-19, the component that allows the virus to enter and replicate in human cells.
Patients showed symptoms on average within 12 days and plasma was collected about 39 days after symptoms appeared.
The scientists then write papers that involve testing the collected plasma for the pseudo-SARS-CoV-2 virus and measuring the effect of the antibodies. In 33% of cases, the neutralizing activity was below detectable levels.
This may mean that the patient has recovered from the infection before the stronger antibodies are produced. It also means that the plasma obtained from these donors will not be as effective for some patients as it is for others.
Most of the samples showed "poor to moderate 'neutralizing activity,'" the researchers said, suggesting a weak antibody response. Even so, these patients were able to survive and improve after COVID-19 infection.
"A closer look reveals that everyone's immune system produces effective antibodies - just not necessarily enough of them," the researchers explained in an announcement.
"This shows that almost everyone can do it, which is very good news for vaccines," said Michel C. Nussenzweig, head of the Rockefeller Laboratory of Molecular Immunology. "This means that if you can make a vaccine that induces these specific antibodies, then this vaccine is likely to be effective, and it will work for a lot of people."
About 1% of donors have amazing neutralizing antibodies. The research team identified 40 antibodies that neutralize the virus, including three unique antibodies that bind to the S protein, which could be further developed into therapeutic and preventive drugs. Even low doses of these antibodies are very effective, and the same antibodies have been found in more than one donor.
"We now know what effective antibodies look like, and we've found similar ones in more than one person," said researcher Davide F. Robbiani. "This is important information for people who are designing and testing vaccines, If they see that their vaccine elicits these antibodies, they know they are on the right track."
The study was published as an unrefereed manuscript in bioRxiv, but is consistent with similar work by other scientists.
While some are working on a vaccine that could prevent SARS-CoV-2 infection, several companies are testing monoclonal antibody drugs that could be used to treat COVID-19 patients and eliminate the virus.
These drugs can also provide temporary immunity to people as long as antibodies circulate in the bloodstream, as they effectively "patrol" the body looking for viruses.
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