Potential measles drug tests well: enzyme-blocking compound saves ferrets from related virus.
"This is still a ways away from human testing," says Alan Hinman, a physician at the Task Force for Global Health, a nonprofit organization in Decatur, Ga. "But it's exciting to see this. I think it has potential to be really useful."
Measles is caused by a pathogen in the genus Morbillivirus. The virus relies on an enzyme called RNA polymerase to infect and spread in a host. Because mammals don't have the same enzyme, researchers are developing experimental compounds that target that RNA polymerase. Scientists report in the April 16 Science Translational Medicine that one such compound, called ERDRP0519, inhibits measles virus in lab tests.
Another morbillivirus causes distemper in dogs. Since that disease is lethal to ferrets, the researchers developed an oral version of ERDRP-0519 and tested it in the animals. The team exposed three ferrets to the distemper virus and, three days later, started giving them two doses daily for two weeks. All three survived.
The compound thwarted viral replication, allowing the animals to launch a prompt immune assault on the virus. The animals' immune systems may even retain some "memory" that would prevent distemper in the future, but this isn't yet established, says study coauthor Richard Plemper, a virologist at Georgia State University in Atlanta.
All other ferrets exposed to the virus died within a few weeks, including nine that received ERDRP-0519 starting a few days before being infected. The timing is significant. Plemper says the effectiveness of the compound rests in its ability to stimulate an immune response in the ferrets when the virus is already present and replicating. If the drug attenuates the virus before it gets a foothold in the body, as was the case for animals receiving the compound before infection, he says, "potentially there may never be an initial strong trigger for the immune system."
Targeting viral enzymes is common, says virologist Diane Griffin of Johns Hopkins School of Public Health. "A lot of antiviral drugs are polymerase inhibitors, but we don't have any for measles."
Plemper says that if ERDRP-0519 succeeds in further testing against the measles virus and is safe in humans, it could work in concert with vaccination to eradicate the disease. In a measles outbreak, health officials try to identify the "index case," the person who introduced measles to an area, Plemper says. Officials then can locate other people exposed to the index case. Those who aren't vaccinated could benefit from treatment with a drug that works like ERDRP-0519 does against canine distemper, he says, limiting new cases and lessening transmission. Measles vaccination typically doesn't work once a person is infected.
Measles kills about 1 in 1,000 infected people. ERDRP-0519 might protect immune-compromised people who are unable to clear an infection, Griffin says, or infants too young to vaccinate.
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|Title Annotation:||BODY & BRAIN; ERDRP0519|
|Date:||May 17, 2014|
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