Ebola virus not mutating as quickly as thought

The virus causing the current Ebola epidemic in West Africa is not evolving as quickly as some scientists had suggested.

In a paper last August, researchers reported that the virus (Zaire ebolavirus) was altering its genes almost twice as fast as it had during previous Ebola outbreaks in Central Africa (SN: 9/20/14, p. 7). However, a new genetic analysis shows that the virus is mutating at roughly the same rate as in past outbreaks, researchers report online March 26 in Science. The finding suggests the virus has not become more virulent or transmissible during the West Africa outbreak.

In the new study, an international team of researchers determined the entire genetic instruction manuals of eight Zaire ebolavirus strains taken from Ebola patients infected in Mali in October and November 2014. The researchers then compared these virus genomes — composed of roughly 19,000 RNA chemical letters — with 99 Ebola virus genomes reported in the August 2014 paper. The most distantly related genomes from the newly sequenced and older collections differ by only 15 RNA chemical letters. That number is similar to the number of mutations reported in earlier Ebola outbreaks, suggesting that the virus is not mutating any faster than expected.

Based on the data, the virus does not appear to be changing in ways that would thwart current Ebola therapies and diagnostic tests, or efforts to develop vaccines, the researchers conclude.