Researchers from the Broad Institute and Harvard University, in collaboration with the Sierra Leone Ministry of Health and Sanitation and other scientists internationally, have rapidly sequenced and analyzed more than 99 Ebola virus genomes. Their findings could have important implications for rapid field diagnostic tests. The team reports its results online in the journal Science.
Researchers sequenced 99 Ebola virus genomes collected from 78 patients diagnosed with Ebola in Sierra Leone during the first 24 days of the outbreak (A portion of the patients contributed samples more than once, allowing researchers a clearer view of how the virus can change in a single individual over the course of infection.) The team found more than 300 genetic changes that make the 2014 Ebola virus genomes distinct from the viral genomes tied to previous Ebola outbreaks. They also found sequence variations indicating that, from the samples sequenced, the EVD outbreak started from a single introduction into humans, subsequently spreading from person to person over many months.
The variations they identified were frequently in regions of the genome encoding proteins. Some of the genetic variation detected in these studies may affect the primers (starting points for DNA synthesis) used in PCR-based diagnostic tests, which emphasizes the importance of genomic surveillance and the need for vigilance.
The research team increased the amount of genomic data available on the Ebola virus by fourfold and used the technique of “deep sequencing” on all available samples. Researchers sequenced at a depth of 2,000 times on average for each Ebola genome to get an extremely close-up view of the virus genomes from the 78 patients. This high-resolution view allowed the team to detect multiple mutations that alter protein sequences—potential targets for future diagnostics, vaccines, and therapies. Read the study.Read more