What Makes Ebola So Deadly?

Ebola viruses prevent the body from mounting an immune response against them, but a new study finds that mutating just one gene makes the virus unable to suppress the immune system.
An electron micrograph of an Ebola virion, with added color. CDC/Cynthia Goldsmith, downloaded from Wikimedia Commons

A new study has found, at a molecular level, what makes the Ebola virus so deadly.

The virus uses a combination of genes to prevent the cells they infect from triggering the immune system, a team of biologists at the University of Texas Medical Branch and the U.S. National Institute of Allergy and Infectious Diseases found. People who die from Ebola generally don’t seem to have had an immune response to the virus at the time of their deaths.

There are Ebola outbreaks every couple of years—sometimes more than once a year—in central and west Africa. Up to 90 percent of those who get sick from the Ebola virus die, according to the World Health Organization. Those who get sick may get fluids through an IV or other support, but there’s no treatment or vaccine.

The U.S. team found how the Zaire variant of the Ebola virus prevents cells called dendric cells from making proteins that call other immune cells over to destroy them when they’re infected. The researchers genetically engineered Ebola Zaire viruses so that they had mutations in four places in their genetic material that the researchers thought were important to the virus’ ability to stop dendric cells from making proteins. The researchers made four different engineered Ebola Zaire viruses, each with mistakes in just one place in its genetic material.

The biologists found that each of those four mutated viruses couldn’t mess up dendric cells, suggesting the virus needs some combination of those four genes to do its deadly work.

The researchers published their work last week in the Journal of Virology.

University of Texas Medical Branch