Scientists find how Ebola disables immune response

Washington: Scientists have found how the deadly Ebola virus blocks and disables the body's natural immune response, a discovery that may guide the development of potential cures or vaccines.

The Ebola outbreak in West Africa, the worst since the virus was first discovered four decades ago, has killed more than 1,000 people since early this year, while nearly 2,000 have been infected, according to the World Health Organisation (WHO).

Dr Gaya Amarasinghe and colleagues from Washington University School of Medicine along with collaborators from the Icahn School of Medicine at Mount Sinai and UT Southwestern Medical Center at Dallas found how the Ebola protein VP24 disrupts the cell's innate immune response, a crucial early step on the virus's path to causing deadly disease.

"We've known for a long time that infection with Ebola obstructs an important immune compound called interferon," said Amarasinghe in the study published in the Cell Press journal Cell Host & Microbe.

"Now we know how Ebola does this, and that can guide the development of new treatments," Amarasinghe said.

According to the researchers, VP24 works by preventing the transcription factor STAT1, which carries interferon's antiviral message, from entering the nucleus and initiating an immune response.

As part of a rapid immune response, the cell allows STAT1 an "emergency access lane" to the nucleus. Rather than block all nuclear transfer, however, VP24 focuses on blocking STAT1's "emergency access lane."

"Normally interferon causes STAT1 to enter the cell nucleus, where it activates the genes for hundreds of proteins involved in antiviral responses," Dr Daisy Leung from Washington University School of Medicine said.

"But when VP24 is attached to STAT1, it can't get into the nucleus," Leung said.

"One of the key reasons that Ebola virus is so deadly is because it disrupts the body's immune response to the infection," said Dr Chris Basler of the Icahn School of Medicine at Mount Sinai.

"Figuring out how VP24 promotes this disruption will suggest new ways to defeat the virus," Basler said.

There is currently no available cure or vaccine for Ebola, which the WHO has declared a global public health emergency.

The virus may be acquired upon contact with blood or bodily fluids of an infected person. Symptoms include fever, sore throat, muscle pain, and headaches. Nausea, vomiting, and diarrhoea follow, along with decreased functioning of the liver and kidneys.