Friday, November 20, 2015

Antiviral agent protects rhesus monkeys from deadly Ebola virus

Rhesus monkeys were completely protected from the deadly Ebola virus when treated three days after infection with a compound that blocks the virus's ability to replicate. These encouraging preclinical results suggest the compound, known as GS-5734, should be further developed as a potential treatment, according to research findings to be presented tomorrow at the IDWeek conference.

Travis Warren, Ph.D., a principal investigator at the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), said the work is a result of the continuing collaboration between USAMRIID and Gilead Sciences of Foster City, Calif. Scientists at the Centers for Disease Control and Prevention (CDC) also contributed by performing initial screening of the Gilead Sciences compound library to find molecules with promising antiviral activity.

The initial work identified the precursor to GS-5734, a small-molecule antiviral agent, which led to the effort by Gilead and USAMRIID to further refine, develop and evaluate the compound. Led by USAMRIID Science Director Sina Bavari, Ph.D., the research team used cell culture and animal models to assess the compound's efficacy against several pathogens, including Ebola virus.

In animal studies, treatment initiated on day 3 post-infection with Ebola virus resulted in 100 percent survival of the monkeys. They also exhibited a substantial reduction in viral load and a marked decrease in the physical signs of disease, including internal bleeding and tissue damage.

"The compound, which is a novel nucleotide analog prodrug, works by blocking the viral RNA replication process," said Warren. "If the virus can't make copies of itself, the body's immune system has time to take over and fight off the infection."

In cell culture studies, GS-5734 was active against a broad spectrum of viral pathogens. These included Lassa virus, Middle East Respiratory Syndrome (MERS) virus, Marburg virus, and multiple variants of Ebola virus, including the Makona strain causing the most recent outbreak in West Africa.

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