Ebola is a terrifying disease, and a new analysis of the virus’s genome has revealed some chilling information: during the 2013-2016 outbreak in West Africa, Ebola mutated to become even deadlier than before. According to two new papers in the journal Cell (published here and here), a series of mutations allowed the virus to more easily infect human cells. This particular strain, the research teams say, has never been seen before in humans or animals.
It’s believed this new strain was able to develop due to the unusual nature of the recent outbreak. In the past, Ebola outbreaks have been fairly short-lived, making it difficult for the virus to mutate. However, this particular epidemic involved tens of thousands of new infections, allowing the virus to adapt better to its human hosts. Perhaps that’s part of why it was so difficult to control – in the end, it infected a staggering 28,616 people across 10 countries, killing 11,310 of them.
When it’s not causing disease in humans, Ebola generally resides in an animal “reservoir” – what type of animal harbors the disease is unknown, but it’s suspected to be fruit bats. This makes it difficult for the disease to develop human-specific adaptations. The West African Epidemic essentially allowed the virus refine its ability to infect us.
The two teams of researchers, hailing from the University of Massachusetts Medical School and the University of Nottingham, both independently conducted their studies using publicly available Ebola gene sequences to track changes to the virus. The key change appears to be in the gene that encodes Ebola’s glycoprotein, a protein that affects cell-to-cell interactions. This makes it easier to spread between humans and other primates.
It’s unclear whether this new, more infectious Ebola virus still exists. Some people could possibly continue to harbor it in their bodies long after they recover from the infection. However, it’s unlikely that it escaped back “into the wild,” given that the new mutation makes it much harder for the virus to infect non-primate animals. Further research into this unique strain will give scientists more information on how to handle the virus in future outbreaks.