Mutations spurred Ebola infections

The Ebola virus that went on a deadly three-year rampage in West Africa before it was smothered earlier this year was on the move in more ways than one. Two new studies show that, in the course of the West African epidemic, the Ebola virus underwent evolutionary changes that made it more deadly and easier to spread from human to human.

In 2013, the Ebola virus started cutting a deadly swath through Guinea, Liberia and Sierra Leone, where it eventually infected 28,000 people, killing 11,000 of them. As it passed swiftly from person to person, a gene bearing the program for a key protein mutated in several places, researchers have found.

In two articles published Thursday in the journal Cell, researchers report that several of the mutations they observed made the virus better at infecting the cells of humans and other primates. Compared to a viral sample collected very early in the outbreak, samples that carried one of the mutations detected by researchers were twice as successful at infecting human cells being cultured in a lab.

By increasing the virus’ ability to hijack human cells and turn them into tiny factories for the production of more virus, it’s possible the detected mutations boosted the deadly spread of Ebola virus in the course of the three-year outbreak.

The researchers underlined that social factors, such as increased urbanization and mobility, did much to accelerate the spread of Ebola during West Africa’s 2013-16 outbreak. But the virus’ changing makeup may also have played a role, they said, since research has shown that genetic shifts that boost a virus’s ability to replicate in human hosts typically result in higher death tolls.

The suspicion that changes in the Ebola virus’s genetic makeup helped fuel the epidemic is also supported by data that link different viral strains to death-toll reports.