Hope for Ebola from drug to treat world's most dangerous virus

Researchers are raising hopes of a new Ebola cure after an experimental drug protected monkeys against the Marburg virus - now considered the world's deadliest.

The Marburg virus is now considered the most dangerous virus on the planet. Photo: CBC

Marburg virus and Ebola virus are deadly cousins. They are both filoviruses (viruses in the Filoviridae family) that cause severe and often fatal hemorrhagic fevers in humans, and neither has a proven vaccine or treatment for humans.

Researchers from Tekmira Pharmaceuticals in Texas (USA) and Vancouver (Canada) gave rhesus macaque monkeys infected with the Angolan Marburg virus an experimental drug using "small interfering RNA" (siRNA). According to the results of the study just published in the journal Science Translational Medicine, 16 monkeys treated with siRNA survived. In contrast, the monkeys that did not receive siRNA all died from the disease.

Remarkably, the primates in the study were able to fight off the world's deadliest virus even when treatment was initiated three days after they were infected.

The experimental siRNA technology blocks the way the Marburg virus makes copies of itself, explains Thomas Geisbert, who led the study. "We demonstrated complete protection against Marburg Angola virus in non-human primates, even when treatment was delayed until day 3, when we could detect infection [the presence of the virus in the blood]," he says.

The siRNA technology holds promise as a treatment for human filovirus infections and could potentially be used to combat the Ebola virus disease outbreak in West Africa, the researchers claim.

In 2010, Geisbert and his colleagues published a study in The Lancet that showed a similar siRNA technology against Ebola, and that it also protected rhesus macaque monkeys shortly after infection. They now plan to investigate whether the approach would be useful in a more realistic setting, where the victims were already showing symptoms.

In Ebola, people generally did not show symptoms within the first 72 hours of treatment trials. Day 3 of infection in a nonhuman primate could be equivalent to day 6 or 7 of infection in a human, Geisbert said.

Another experimental Ebola drug, ZMapp, works in a completely different way. It contains three antibodies that block the Ebola virus’s ability to attach to and enter host cells. So far, two American medical workers and three Liberian doctors who have been treated with ZMapp have shown signs of recovery, but a Spanish pastor has died from Ebola despite also being treated with the experimental ZMapp.

Experts warn that it is still unclear whether ZMapp helped or hindered patients' recovery.

According to vietnamnet