A compound found in a Chinese medicinal herb has shown promise as a possible treatment for the viral disease Ebola, researchers say.
The compound known as tetrandrine can effectively isolate or "imprison" the Ebola virus inside cells it has invaded so it cannot spread in the body and do its usual harm, they announced.
In lab experiments the tetrandrine molecule has inhibited infection in human white blood cells, and has prevented the virus disease in mice, the researchers report in the journal Science.
"When we tested in mice, the drugs stopped virus replication and saved most of them from disease," says Dr. Robert Davey in the Department of Immunology and Virology at Texas Biomedical Research Institute.
"The work has revealed a new chink in the armor of Ebola virus," he says, adding this treatment approach possibly could be used to help people in 2 to 5 years.
There is currently no approved drug-based treatment or vaccine for the virus, which in its most recent outbreak killed more than 9,400 people and is continuing to infect thousands in West Africa.
The virus results in hemorrhagic fever and can spread from person to person through contact with bodily fluids.
To be successful in infecting a cell, the Ebola virus must move deep inside it before breaking out of a cell's bubble-like intracellular transport structures known as endosomes.
Channels important for controlling movements of the "bubbles" within a cell can be blocked by tetrandrine, the researchers found, effectively imprisoning the virus inside the "bubbles" so it can't break out and infect the cell and then spread.
Because it can't break out and replicate, it's "destroyed by the cell," Davey says. "This stops infection."
Tetrandrine is a compound derived from the root of a medicinal herb, Stephania tetrandra.
Currently the only country that has approved the drug for human use is China, where it is used to lower blood pressure.
There are potential drawbacks to using the drug as an Ebola treatment, notes Darryl Falzarano, a virologist at the University of Saskatchewan who was not part of the study.
Besides being banned in almost all countries, a human dose equivalent to what was administered to mice in the lab tests could prove to be toxic, he says.
In addition, the effectiveness of the drug in the mice tests was reduced if the treatment was delayed by a single day, he pointed out.
A drug that can block infection in someone already exposed to the virus is likely a long way off, he predicts, suggesting current vaccine research is the best candidate for a solution to Ebola outbreaks.
"I still think that implementing one of the vaccine platforms will have the most significant public health impact," Falzarano says.
