National Institutes of Health (NIH) scientists have added new molecular evidence that the Ebola virus (EBOV) circulating in West Africa since late 2013 is no more virulent than EBOV seen in previous outbreaks. Their study examining interferon inhibition was published in Nature Communications in August 2015.
Results of Study
Two EBOV proteins, VP24 and VP35, are known to interfere with the body’s immune responses by suppressing the activity of virus-fighting proteins called interferons. In their new study, the scientists from NIAID examined more than 100 EBOV strains whose genome sequences had been published in scientific reports. The sequences studied came from the virus responsible for the recent West African epidemic and from the one that caused the first recorded outbreak of Ebola virus disease in 1976. The investigators constructed EBOV genes expressing VP24 and VP35 proteins and placed them into 293 human tissue culture cells. Next, they compared how much the VP24 and VP35 variants hindered interferon production.
In every study measurement, VP24 and VP35 acted similarly whether they were derived from the current outbreak strain or prior outbreak strains, providing strong evidence that the newest EBOV strains are no more virulent than older viruses.
The scientists will continue monitoring newly published EBOV genome sequences for changes, since this study focused only on genome sequences from the beginning of the outbreak. They also will continue to explore the functions of VP24 and VP35 and their relation to immune responses.
Dunham E et al. Assessing the contribution of interferon antagonism to the virulence of West African Ebola viruses. Nature Communications. DOI: 10.1038/ncomms9000 (2015).