By Chioma Umeha
Fresh revelations emerged on Monday, concerning
the dreaded Ebola Virus Disease (EVD) which claimed thousands of lives in West
Africa, including Nigeria as researchers identified mutations in the virus that
increased its ability to infect human cells from 2013 to 2016. The findings
have been reported by two independent teams of researchers according to online
news reports.
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 weekend, 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’s 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 2013-2016 outbreak. But the virus’s 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. In the West African outbreak,
humans infected with strains of Ebola virus bearing the most potent mutation
detected in the new research were more likely to die of the disease than those
infected with an Ebola strain without the mutation.
The new research helps shed new light on an Ebola
outbreak that racked West Africa and frightened the world. It underscores that
when a disease-causing virus escapes from its “reservoir” – a nonhuman animal
population in which it continues to circulate between human outbreaks (for
Ebola, it’s bats) -that virus gains new opportunities to adapt to human hosts
and grow stronger. And once such a virus begins passing easily among large
numbers of humans, opportunities for further mutation proliferate.
Evolution is a fitful process, and some of the
mutations found by the research teams made strains of Ebola virus less
virulent. Also, not all genetic changes in a virus are important. Some viral
mutations are effectively one-off events that are not passed on to every copy
of the virus as it goes forth and replicates.
The mutations found in the new studies, however,
appear to be changes that were carried forth to their viral progeny. For that
reason, and because the mutations detected in the new research seem to have
improved the virus’s ability to enter and take over human cells, these findings
appear to be important.
