The Ebola virus behind the current outbreak in West Africa is a new strain, according to a genetic analysis of the RNA virus presented in the New England Journal of Medicine. The virus has caused some 120 deaths, mostly in Guinea, the Associated Press adds.
An international team of researchers led by Stephan Günther from the Bernhard Nocht Institute for Tropical Medicine in Germany obtained blood samples from 20 patients hospitalized in three Guinean towns with fever, diarrhea, vomiting, or hemorrhage who tested positive for the presence of filovirus. The team sequenced viral RNA from the three patients determined by RT-PCR to have the highest viral load using a Sanger platform.
The group then aligned that viral sequence to the 48 complete filovirus genome sequences housed in GenBank. From its phylogenetic analyses, the team found that the Guinean strain show 97 percent identity to Ebola virus strains from the Democratic Republic of Congo and Gabon, though Bayesian and maximum-likelihood analyses indicated that the Guinean EBOV had a separate, basal position within the EBOV clade.
"This suggests that the EBOV strain from Guinea has evolved in parallel with the strains from the Democratic Republic of Congo and Gabon from a recent ancestor and has not been introduced from the latter countries into Guinea," Günther and his colleagues write.
Günther notes to the AP that the animal source of the virus is unknown, but a search is ongoing.