New studies show that treatments targeting specific viral genes protected monkeys infected with deadly Ebola or Marburg viruses. Furthermore, the animals were protected even when therapeutics were administered one hour after exposuresuggesting the approach holds promise for treating accidental infections in laboratory or hospital settings.
The research, which appears in today's online edition of the journal Nature Medicine, was conducted by the U.S. Army Medical Research Institute of Infectious Diseases in collaboration with AVI BioPharma, a Washington-based biotechnology firm.
Working with a class of compounds known as antisense phosphorodiamidate morpholino oligomers, or PMOs, scientists first performed a series of studies with mouse and guinea pig models of Ebola to screen various chemical variations. They 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.
Encouraged by these results, the team conducted "proof of concept" studies in which 9 rhesus monkeys were challenged with lethal Ebola virus. Treatment was initiated 30-60 minutes after exposure to the virus. In these studies, 5 of 8 monkeys survived, while the remaining animal was untreated. Further experiments, including a multiple-dose evaluation, also yielded promising results, with 3 of 5 monkeys surviving in each of the AVI-6002 treatment groups when they received a dose of 40 mg per kg of body weight.
According to first author Travis K. Warren of USAMRIID, antisense drugs are useful against viral diseases because they are designed to enter cells and eliminate viruses by preventing their replication. The drugs act by blocking critical viral genetic sequences, essentially giving the infected host time to mount an immune response and clear the virus.
Ebola and Marburg cause hemorrhagic fever with case fatality rates as high as 90 percent in humans. The v
|Contact: Caree Vander Linden|
US Army Medical Research Institute of Infectious Diseases