3 November 2014
New research in mice suggests that genetic factors may play a key role in survival among Ebola virus infected patients.
A paper in Science reports on the outcomes of a mouse model of Ebola haemorrhagic fever suitable for linking specific genetic features of mice with disease characteristics. Infection with a mouse-adapted version of the Ebola virus causing the current (2014 West African) human outbreak caused highly variable disease in different mouse strains.
A significant minority of the mice appeared to show complete resistance to disease; of those that showed disease symptoms, mortality rates varied from 25-70%.The observed spectrum of disease in the mouse model is said to be similar to that observed among affected humans in the current outbreak.
The authors conclude that genetic factors may play a significant role in influencing the outcome of Ebola infection in humans who do not have potentially protective immune responses from prior exposure to Ebola or a similar virus. Insights from learning more about these factors are likely to be valuable in the evaluation and development of novel strategies to combat the disease.
Commenting on the study, Professor Andrew Easton of the University of Warwick, noted various limitations, not least the obvious differences between humans and mice, and in the degree of genetic variability observed in human populations compared with laboratory-bred mouse strains. He also said that the role of environmental factors and the general health of infected patients would be significant. More positively, he also noted that the new research suggested that "it may not be necessary to completely eliminate Ebola virus from the body during infection to ensure that there is no disease, and that reduction of virus growth in the body may offer alleviation from some aspects of the disease".
Individuals with genetically endowed immunity to important human pathogens have always been of interest as a source of potentially vital information in developing new treatments – for example, the CCR5 mutation associated with resistance to HIV infection. At present, we remain a very long way off understanding the human genetic factors that may influence the course of Ebola virus infections. However, even a suggestion that any of the potential new treatments being fast-tracked to tackle the current outbreak may not need to be a magic bullet to have at least some protective effect is promising.