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Genomics lab in Liberia helps scientists monitor Ebola virus
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While evidence implies the introduction of Ebola virus Makona into Liberia resulted from a single source, recently published data from the first advanced genomic research facility in the country suggest additional international movement also may have occurred.
For their study, the researchers examined genome samples from 25 Ebola patients aged 1 to 67 years. Patients were treated in seven Ebola treatment centers and had lived in seven of Liberia’s 15 counties. The researchers tested the most recent oral swab or plasma samples from each participant and worked back to older samples.
This genome analysis revealed multiple evolutionary lines among the patients’ samples, all of which resembled natural diversification stemming from a single introduction of the virus. Evidence of outside strains, however, also suggested the possibility of at least one instance of international exchange.
“Molecular dating places the common ancestor to all the sampled isolates from Liberia during May 2 to July 9, 2014 (95% highest posterior density interval), which corresponds with the early days of the outbreak in Monrovia,” the researchers wrote. “However, we cannot rule out ongoing Ebola virus exchange among Ebola virus disease-infected countries. In fact, shared ancestry among three isolates from Liberia and the four available sequences from Mali suggests some level of international movement.”
The researchers also said the evolutionary rate of the Ebola virus samples they studied was in line with previous estimates.
“The pace of change is generally consistent with previous estimates of mutation rate,” they wrote. “Six of the changes we observed are within known binding sites for sequence-based Ebola virus medical countermeasures. However, the diagnostic and therapeutic impact of Ebola virus evolution within Liberia appears low at this time.”
Until recently, samples of the Makona strain were sent to the United States for genome sequencing and analysis, Jeffrey R. Kugelman, PhD, viral geneticist at the U.S. Army Medical Research Institute of Infectious Diseases, said in a press release. Because sequencing can take 3 days, power outages or fuel shortages could delay that process, according to the release.
With the genomics lab now located in Liberia, however, health officials should reap significant benefits.
“Providing genetic sequencing for molecular evidence to support epidemiological descriptions of transmission chains, and monitoring viral pathogens for target erosion in the binding sites of diagnostics and therapeutics are proving to be critical assets in fighting high-mortality disease outbreaks,” Kugelman told Infectious Disease News. “Ensuring that these capabilities are available in close proximity to the point of care ensures that these answers are provided in a timely fashion, providing real-time support rather than academic discussion for future outbreaks.” – by David Jwanier
Disclosure: The researchers report no relevant financial disclosures.
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