The reasons why people some people die and others survive Ebola are down to genetic factors, researchers said last night.
Some people who are exposed to the deadly disease can resist it, while others suffer moderate to severe illness and recover. Others suffer bleeding, organ failure and shock and will die from it.
Earlier investigations have found that the Ebola virus does not change to make it more or less dangerous within an individual. Now, scientists from the Katze Laboratory at the University of Washington, USA, have developed the first model using laboratory mice to imitate the main characteristics of human Ebola haemorrhagic fever.
Working with colleagues from the National Institutes of Health’s Rocky Mountain Laboratories, Montana, and University of North Carolina at Chapel Hill, the researchers say that genetic factors play a significant role in disease outcome.
Writing in the 30 October edition of Science, systems biologists and virologists Angela Rasmussen and Michael Katze and colleagues describe how they examined mice infected with a mouse form of the same species of Ebola virus that has caused the 2014 West Africa outbreak.
Conducting their research in a highly secure, state-of-the-art bio-containment safety level 4 laboratory in Hamilton, Montana, they discovered that all of the mice lost weight in the first few days after infection, while 19% remained unfazed. They survived, regained their lost weight within two weeks and had no gross pathological evidence of disease.
The study found 11% were partially resistant and less than half of these died. However, 70% of the mice had a greater than 50% mortality. Of this group, 19% had liver inflammation without classic symptoms of Ebola, while 34% had blood that took too long to clot, a hallmark of fatal Ebola haemorrhagic fever in humans. Those mice also had internal bleeding, swollen spleens and changes in liver colour and texture.
“The frequency of different manifestations of the disease across the lines of these mice screened so far are similar in variety and proportion to the spectrum of clinical disease observed in the 2014 West African outbreak,” Rasmussen said. “Our data suggest that genetic factors play a significant role in disease outcome.”
Katze said he hoped that medical researchers will be able to use their findings as part of their research for a therapy or vaccine.
Science 30 October 2014
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