Antibodies that could one day stop Ebola in its tracks have been jointly developed by the U.S. army and a team of scientists. The hope is to create a universal answer to the different Ebola species, between which there are critical differences.
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The research on the potential therapy was done in mice and is nowhere near being relevant to humans. But it is a big step forward in the fight against the deadly hemorrhagic disease, which has killed tens of thousands of people in Africa in recent years.
Ebola terrifies people mainly for the gruesomeness of its symptoms, high mortality rates, and the lack of a cure. Moreover, survivors may "host" viral particles for much longer than thought, causing chronic suffering. Neither therapy nor vaccine exists for any of the five Ebola species - Zaire, Sudan, Bundibugyo, Reston, and Tai Forest.
The five Ebola species have substantial differences between them, and few antibodies with cross-neutralizing properties have been described to date. Now antibodies that recognize and "potently neutralize" the two deadliest Ebola strains, Zaire and Sudan, have been engineered by scientists at the Albert Einstein College of Medicine working with the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID).
"Together, Zaire and Sudan Ebola viruses have been responsible for 95 percent of Ebola-related deaths from 1976-2012," says Jonathan R. Lai of the Albert Einstein college, co-author of the paper published Wednesday in Nature, "Bispecific Antibody Affords Complete Post-Exposure Protection of Mice from Both Ebola (Zaire) and Sudan Viruses".
"Neutralized" means the virus did not infect cells in test tubes, Lai explained to Haaretz, adding: "In this study, we also characterized the ability of the antibodies to act therapeutically in mouse models" (meaning, in mice).
Treat, not just prevent
Antibodies are large proteins produced by our immune systems to identify and neutralize pathogens such as bacteria and viruses. By nature, they are highly specific: a given antibody will identify only one target. A natural antibody specific for Zaire Ebola probably wouldn’t recognize Bundibugyo Ebola, for instance.
While the antibody engineered by the army and science can recognize two Ebola species, the hope is to develop therapeutic antibody candidates against multiple Ebola viruses, says Lai.
So far the antibody engineered to recognize the Zaire and Sudan species has not been tested against any other species, Lai says – that is next.
Lai distinguishes between therapeutics and vaccines. Vaccines consist of portions of the virus. The purpose of administering them is to induce our immune systems to recognize the virus and create antibodies against it. Then, if exposed to the actual whole nasty virus, our bodies are primed to recognize it and attack it before it can kill us.
"An immunized (vaccinated) individual does not develop an infection even upon exposure to the virus," Lai sums up. "A therapeutic is an agent that is delivered after infection, which attacks the virus and slows down or eliminates the progression of the infection."
"Immunotherapeutics" are therapeutics that are made of or inspired from the natural immune system, he adds.
One thing. Mice are not naturally infected by Ebola. How valuable is information about an engineered antibody that works against two species of Ebola that don't attack mice anyway?
The antibodies were tested in two sets of mouse experiments in which either the virus or the mouse was adapted to mimic a natural infection, Lai explains. Ebola may work very differently in people, fruit bats and these "adapted" mice, he acknowledges. "Our report is an encouraging first step but we are still very far away from knowing if our antibodies could work in humans." Before testing on humans, though, the therapeutics will likely be tested on other animal models, including primates.
In other news of Ebola, Russian President Vladimir Putin announced yesterday that Russia has developed a highly effective Ebola vaccine, which a state official said has been tested on people. Health Minister Veronika Skvortsova stated that one of the vaccines Russia tested "provides 100 percent immunity to the disease". More detail has been lacking.