When a new virulent strain of the deadly Ebola virus broke out in West Africa this spring, a Harvard researcher who studies how evolution shapes the genome sprang into action. A three-person team from Harvard and Tulane universities promptly departed for Sierra Leone to help instruct staff at a local hospital on how to conduct a genetic test for the new strain, which has infected nearly 300 people so far.
The gulf between science and medicine in this case may seem impossibly wide: The science involves fascinating academic questions about the signatures that evolution left behind in our DNA, while the medical issues in such an unfolding public health crisis are tangible and urgent.
But for Pardis Sabeti, a genetics researcher at Harvard and the Broad Institute, the two threads are tightly woven together. Insights gained from each part of her work may prompt new research questions — and possibly new public health strategies.
For years, Sabeti and her colleagues have studied the genome, searching for areas where natural selection had left its imprint.
To her surprise, Sabeti found that one of the genes with the strongest signs of evolution’s handiwork was involved in the relatively obscure Lassa fever, which is caused by a virus carried by rodents in rural areas of West Africa.
“Lassa fever got called to my attention in 2007 because the top signal in the genome of evolutionary selection was a gene critical for the entry of the virus,” Sabeti said. “And I became interested in whether this was an ancient virus . . . because it had a signal that suggested humans have been fighting it for a long time.”
Based on her study of evolution in the human genome, Sabeti became more interested in Lassa fever, a deadly hemorrhagic infection that is considered an “emerging” disease. It was only identified a few decades ago, but is probably thousands of years old. She began to collaborate with hospitals, first in Nigeria and then in Sierra Leone, to study the virus and how it evolves, as well as to understand how people living in those areas may be exposed to the virus and develop resistance to it in some cases.
That work led to partnerships, and Sabeti and colleagues found themselves helping build the infrastructure to deal effectively with the disease and training staff to detect symptoms early and monitor people for signs of exposure to the virus. With early detection, staff can treat victims of Lassa immediately with a powerful antiviral medication.
Before 2008, when Sabeti and her team began to work with the Nigerian hospital, she was told that a handful of health care workers died each year of Lassa fever.
But since her team began to collaborate with hospital staff there, new technology is in place and new policies have been developed, resulting in the elimination of staff deaths from the disease.
When Ebola was detected in Guinea this spring, Sabeti and her collaborators were ready to apply those diagnostic capabilities to that virus, which was likely to spread to the neighboring countries where they had been working.
Samples of the virus are being sent to the Broad Institute, a genomics research center in Cambridge, to be sequenced and studied.
To continue outreach and efforts to build on-the-ground expertise, 20 scientists from Sierra Leone and Senegal will be spending eight weeks at the Broad Institute and at Harvard this summer to learn and do scientific research.
“We’re just really focused on building capacity there and having them do everything,” Sabeti said. “They are the ones seeing the cases all the time.”