San Diego scientists have published the most detailed picture yet of the experimental Ebola drug ZMapp, and the images suggest the formula could be improved.
ZMapp is a cocktail of three antibodies, each aiming to latch onto the Ebola virus and prevent it from infecting healthy cells. In a study published Monday in the Proceedings of the National Academy of Sciences, researchers at The Scripps Research Institute in La Jolla find that two of the antibodies bind to the same site on the virus.
Study co-author Erica Ollmann Saphire concludes these two antibodies may be redundant.
"They might be doing exactly the same thing," she said. "If we have two which are doing the same thing, we should figure out which one of them is most effective — or can be grown to higher yields — and just use that one."
A handful of patients have received ZMapp during the current Ebola outbreak, but rigorous trials are needed to truly know whether the drug helped survivors.
The company behind ZMapp, the small San Diego-based firm Mapp Biopharmaceutical, has said supplies are currently exhausted. The U.S. government has pledged up to $42.3 million to help speed production of ZMapp, which is manufactured in bioengineered tobacco leaves.
Saphire's colleague Andrew Ward used single particle electron microscopy to render the new images. They reveal that ZMapp's third antibody binds to another site. It doesn't stop the virus from entering cells, but instead appears to flag the virus, marshaling the body's immune system in attempts to destroy it.
"It seems to be a beacon, alerting the immune system to the presence of the infection," Saphire said.
Saphire said the study also shows that whatever mutations the Ebola virus has undergone during this outbreak, its potential vulnerabilities to ZMapp appear to have remained intact.
Saphire's lab continues to study candidate antibodies for potential reformulations of ZMapp, a process she says will move faster now that her crowd-funding campaign has drawn enough money to pay for expensive new analysis equipment.
"These images are like enemy reconnaissance," Saphire said. "They give you maps of where you want to hit."
