Via Nature News & Comment: Drug saves monkeys from close relative of Ebola. Excerpt:
A medicine administered days after infection can save monkeys from a deadly virus related to Ebola, researchers report in Science Translational Medicine.
“This clearly starts to move into the realm of being a therapy, rather than a post-exposure treatment,” says virologist Gene Olinger, principal science adviser for contract-research organization MRIGlobal in Kansas City, Missouri, who was not involved in the study. “It's a tougher point to intervene, so it's important that they've demonstrated this.”
The drug, called TKM-Marburg, was developed by pharmaceutical company Tekmira in Burnaby, Canada, to treat Marburg virus. Like its close relative Ebola, the Marburg virus causes a lethal haemorrhagic fever; an outbreak in Angola in 2004–05 killed more than 90% of people infected, and the virus is circulating in countries affected by the current Ebola outbreak, such as Sierra Leone.
In the latest study, researchers used the Tekmira drug against Marburg in 16 rhesus macaques (Macaca mulatta), divided into four groups that each received the treatment at a different time: 30–45 minutes after infection, or one, two or three days after infection. All of the treated monkeys — including the four given the drug three days after exposure, roughly equivalent to day six of a human infection — survived, whereas four untreated animals died.
Study author Thomas Geisbert, a microbiologist at the University of Texas Medical Branch in Galveston, says that this is the first time that a single drug has been shown to save animals from Marburg when it is administered days after the virus enters their bodies. Currently the only way to confirm a Marburg or Ebola infection in humans is to wait several days until the virus has reached detectable levels in a person's blood.
The Tekmira drug uses pieces of genetic material — small interfering RNAs, or siRNAs — to disrupt the Marburg virus’s ability to copy itself, thus stalling the course of infection. The siRNAs are encased in an envelope made of a fat-like material.
Some researchers say that the current study could aid in the decision about whether to use experimental medicines in the current Ebola outbreak. No medicines have yet been approved to treat the virus, but several are in development — including one, TKM-Ebola, made by Tekmira using similar techniques to TKM-Marburg. The World Health Organization (WHO) said on 12 August that the use of these unapproved medicines would be ethically acceptable in the current situation.
The TKM-Marburg research “shows that you have a window of opportunity when you can actually intervene before the tipping point when people are going to be too ill to recover”, says Amesh Adalja, an infectious-disease physician at the University of Pittsburgh Medical Center in Pennsylvania.