SEP 11, 2015 2:14 PM PDT

Ebola "Escape Variants" Allow the Virus to Avoid Destruction

WRITTEN BY: Kara Marker
Ebola is a highly infectious, hemorrhagic disease that caused a huge outbreak last year, primarily in West Africa. Word of the devastating virus has taken over the news ever since, and scientists and physicians are still working to completely alleviate current cases and prevent future infections. 

According to the Centers for Disease Control and Prevention, the most recent Ebola outbreak was the largest ever seen. Ebola overwhelms the immune system, eliminating its ability to function normally and fight off the infection. The virus is spread through contact with contaminated body fluids. Common symptoms (fever, headache, unexplained bleeding, vomiting, fatigue) occur between 2 and 21 days after exposure to contamination. 


Since Ebola is caused by a virus and not by bacteria, scientists had to come up with a treatment outside of the realm of antibiotics. Currently, Ebola patients are treated with a mixture of antibodies to help boost the immune system back to its original strength. After this treatment was successful in primate trials, it was approved for human clinical trials, then later approved for widespread use. 

Unfortunately, American researchers recently reported in the journal Cell Reports that Ebola is beginning to mutate in response to the antibody treatments. These genetic changes, called "escape variants," have been found in the Ebola DNA of nonhuman primates who died despite administration of the antibody mixture treatment. When these animals died unexpectedly, scientists extracted and sequenced viral DNA, looking to explain the animals' death.

"Two clusters of changes" were found in the viral Ebola DNA, and "several of those changes corresponded with the viral target sites of two of the cocktail's antibodies." This means that selective pressure on the Ebola virus from the debilitating antibody treatment induced the survival of the Ebola viral strains that had mutated sequences different than what the antibodies were designed to attack. Once these viral strains survive, they can multiply in numbers large enough to kill the infected patient - in this case the primate. Although initially there was no telling how often these mutations were occurring in other cases, soon after the same scientists found 4 common sites of viral DNA change in a different animal who had died after antibody treatment for Ebola. 

There's still plenty of chance that different mutations are occurring in response to antibody treatment. Some could cause the virus to be defective and non-pathogenic, but some could cause it to be treatment resistant and more dangerous than ever. Scientists treating Ebola will have to take this mutation pattern into serious consideration as they go forward with Ebola treatment and prevention. 

Check out the following video below for a chilling overview of the history of the Ebola virus.


Source: Medical Xpress
 
About the Author
  • I am a scientific journalist and enthusiast, especially in the realm of biomedicine. I am passionate about conveying the truth in scientific phenomena and subsequently improving health and public awareness. Sometimes scientific research needs a translator to effectively communicate the scientific jargon present in significant findings. I plan to be that translating communicator, and I hope to decrease the spread of misrepresented scientific phenomena! Check out my science blog: ScienceKara.com.
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