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Broadly Acting Antibodies in Blood of Ebola Survivors Offer Ample Protection Against Disease

Scientists supported by the NIAID discover a set of broadly neutralizing antibodies in the blood of Ebola survivors capable of providing substantial protection against the disease.

Since it was first described in 1976, Ebola virus continues to emerge periodically in several African countries. A recent outbreak of the disease sprung up this year in the Democratic Republic of Congo, claiming several lives and further underscoring the need for available licensed treatments.

Now, scientists supported by the National Institutes of Health’s National Institute of Allergy and Infectious Diseases (NIAID) have detected a set of broadly neutralizing antibodies (bNAbs) in the blood of Ebola survivors that may hold promise for future treatment.

In fact, NIAID scientists report that in animal studies, 2 of the antibodies proved to be capable of providing significant protection against 3 species of bacteria known to cause deadly illness in humans: Zaire ebolavirus, Bundibugyo ebolavirus, and Sudan ebolavirus.

For their study, researchers from Vanderbilt University Medical Center and the University of Texas Medical Branch assessed blood plasma collected from 17 individuals who survived Ebola infection.

Ebola is known to use glycoprotein as a way to attach to cell membranes and induce infection, according to a recent press release. In isolates collected from 2 Ebola survivors, the team discovered antibodies that adhered to the glycoprotein from the 3 species of Ebola bacteria, preventing the deadly viruses from getting into host cells, and thus, preventing infection.

The team then conducted several experiments in an effort to define interactions between several forms of viral glycoprotein and 3 of the bNAbs that had been isolated from the plasma specimens. Their observations led them to conclude that not just 1, but several mechanisms are allowing the antibodies to hinder the actions of all forms of glycoprotein; these mechanisms all work to stop viral entry into the host cell, thus, preventing infection.

In addition to this finding, the team was able to go so far as identify a single bNAb, referred to as EBOV-520, that binds to a part of the glycoprotein in a way that prevents the glycoprotein from interacting with NPC1, a cell surface protein that is central to the infection cycle.

Currently, there are no antiviral drugs that have been licensed by the US Food and Drug Administration to treat Ebola in those infected. Drugs that are currently in development are focused on keeping the virus from making copies of itself, according to the Centers for Disease Control and Prevention.

As such, symptoms of the disease are often treated as they present; early treatment interventions are helpful in improving the chances of survival but the average case fatality rate for Ebola remains around 50% with these rates varying from 25% to 90% in past outbreak settings.

Based on these promising findings, however, the team concludes that broadly neutralizing antibodies can be further developed for potential use as therapeutic molecules that can be used against several different species of Ebola.