In this week's Nature Medicine, a study brings a ray of success in researchers' quest to fight the deadly viruses Ebola and Marburg. Testing a new approach on monkeys, scientists at the
U.S. Army Medical Research Institute of Infectious Diseases saw most of the monkeys survive a normally fatal Ebola infection—and all of them who had Marburg lived.
Within an hour of infecting the primates, researchers gave them antisense phosphorodiamidate morpholino oligomers, or PMOs.
The morpholino oligomers are a new class of drugs in a family of what is known as antisense nucleotides. Antisense nucleotides are designed to bind tightly to specific areas of viral messenger RNA, blocking replication. Such compounds already are being used to treat certain types of cancer and cytomegalovirus infections, and they are being tested against HIV [Los Angeles Times].
The scientists created two different PMOs, one targeting each virus. Five out of the eight rhesus monkeys that received the PMO targeting Ebola
survived their bout with that virus. All 13 that were infected with Marburg and then given that PMO survived. The monkeys still got sick, but by blocking the virus
' replication, the PMO treatments appeared to provide the primates enough time to muster their immune systems and fight back against the deadly infection. The PMO idea has been around for a while. The lab first created a human-grade version six years ago, when a worker accidentally pricked her finger while working on rats with Ebola.
The female worker was isolated, but found to be uninfected, so the human-grade antisense drug was not used on her. But the facility has worked with biotechnology company AVI BioPharma to develop antisense drugs to be used in human clinical trials [The Independent].
Scientists are still miles from a vaccine: There's no way to know whether the treatment would work similarly on humans, and clinical trials will have to be done on primates. And in this case, the U.S. Army researchers were so successful because they managed to administer the PMOs just after infection—something not possible in many cases of human infection. Against Ebola, however, any step is an important one.
There are at present no effective treatments or vaccines against either of the viruses, which are highly infectious and have caused particular concern because of the possibility of them being used in biowarfare or as a terrorist weapon [The Independent].
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Image: Wikimedia Commons