A new approach from AVI BioPharma was successful in helping save monkeys already infected with the Ebola virus--and the animals were protected even when therapeutics were administered one hour after exposure. These results suggest AVI's approach holds promise for treating accidental infections with Ebola and Marburg in laboratory or hospital settings, according to a statement from the U.S. Army Medical Research Institute of Infectious Diseases.
Ebola and Marburg cause hemorrhagic fever with fatality rates as high as 90 percent in humans. While, there are no available vaccines or therapies, scientists are looking with hope at a class of compounds known as antisense phosphorodiamidate morpholino oligomers. The scientists first performed a series of studies with mouse and guinea pig models of Ebola to screen various chemical variations and arrived at a therapy known as AVI-6002, which demonstrated a survival rate of better than 90 percent in animals treated either pre- or post-exposure.
The team then conducted proof of concept studies in which nine rhesus monkeys were challenged with lethal Ebola virus. Treatment with AVI-6002 was initiated 30-60 minutes after exposure; five of eight monkeys survived, while the remaining animal was untreated. Investigators also conducted two similar pilot studies to assess the efficacy of AVI-6003 against the Marburg virus. All 13 infected animals receiving AVI-6003 survived.
"This report of successful early post-exposure treatment of filovirus hemorrhagic fever is significant on its own," says Colonel John Skvorak, USAMRIID commander. "But the drug characteristics of these PMOs also support investigation of potentially broader therapeutic applications." The INDs for AVI-6002 and AVI-6003 have been submitted to the FDA, and they are now open to proceed with clinical trials.
Although the results are "a potentially important proof of concept," researchers are "a long way from a product that can be used with confidence against human infections," says virologist Alan Schmaljohn of the University of Maryland School of Medicine, who was not involved in the research, as quoted by the LA Times. He also cautioned that the drugs were given within an hour after infection and that they could be much less effective later in the course of the disease or against a more aggressive strains. But, as the paper notes, the drugs represent the hope against two viruses that can be used by bioterrorists.