Washington: Scientists have found an antibody that binds to Ebola virus and its deadly cousin Marburg, pointing to new treatments to fight an entire family of viruses.
Marburg virus is up to 90 per cent lethal - and doctors are desperate for tools to fight it, researchers said.
Now scientists at The Scripps Research Institute (TSRI) in US have captured the first images showing how immune molecules bind to a site on the surface of Marburg virus.
The images are like enemy reconnaissance, showing scientists how to target the virus's weak spots with future treatments.
The research team is also the first to describe an antibody that binds to both Marburg and Ebola viruses, paving the way for new antibody treatments to fight an entire family of viruses.
"These cross-reactive antibodies are a straightforward route to a therapeutic," said TSRI Professor Erica Ollmann Saphire, senior author of the study and co-director of the Global Virus Network Centre of Excellence at TSRI.
"You could use these antibodies directly against Marburg virus or - with a bit more engineering - use them to also target Ebola virus," said Saphire.
Marburg virus is spread to humans by bats and can cause massive hemorrhaging and organ failure, just like Ebola virus.
In 2005, a Marburg outbreak in Angola killed 329 people, mostly children and health-care workers.
"Marburg is just as likely as Ebola to migrate to a densely populated area," said Saphire.
The new study focuses on an antibody discovered in the blood of a Marburg survivor. By studying how the antibody binds to the virus, the researchers hoped to find new points of attack on Marburg's surface.
The project was a six-year effort in the Saphire lab. Takao Hashiguchi, a former TSRI research associate, and Marnie Fusco, a TSRI research assistant, figured out how to grow crystals of the antibody attached to its viral target.
This crystal was then exposed to X-ray diffraction at the Photon Factory synchrotron in Tsukuba, Japan, revealing its shape in three dimensions.
The team's work showed how the antibody attaches to Marburg virus, blocking the virus's ability to bind to a receptor and get its genetic material into human cells.
This was also the first time that Marburg's glycoprotein had been seen in the form it takes as it infects cells.
Marburg and Ebola viruses enter cells the same way, so the researchers wondered if the antibody could also inactivate Ebola virus by binding to the same site.
The work of TSRI Staff Scientist Zachary Bornholdt showed that it did bind to Ebola - and provided a crystal structure of the same antibody bound to Ebola virus.
The finding was published in the journal Cell.