New Ebola drug clears virus from monkeys - results published in 'Nature'

More than 26,000 people have been infected with Ebola since the outbreak began

An experimental Ebola drug cured three monkeys intentionally infected with the virus, according to a study published in Nature magazine.

The development marks the first such success against the strain of Ebola that killed up to 10,000 people in West Africa’s 2014-2015 outbreak.

Although other experimental treatments appeared to help Ebola patients last year, especially in the United States, those one-time uses cannot prove efficacy against the “Makona” strain, since patients’ recovery might be due to other causes.

Similarly, drugs, including Mapp Biopharmaceutical’s ZMapp, cured monkeys in lab experiments, but in a strain of Ebola different from that responsible for the current outbreak, the worst ever recorded.

“We can’t say for certain that an experimental drug that works against one strain will work in another, even if they’re almost identical genetically,” said Thomas Geisbert of the University of Texas Medical Branch, senior author of the study published in the journal Nature.

In the experiment, six rhesus monkeys were infected with huge doses of the Makona strain. Three days later, three received an infusion of a drug developed by Tekmira Pharmaceuticals Corp, a cocktail of “small-interfering RNAs” (siRNAs) encapsulated in a fat droplet called a lipid nanoparticle.

The siRNAs bind to two of the virus’s seven genes, silencing them and thereby preventing the virus from replicating.

All three treated monkeys survived despite fevers and enormous blood levels of virus. 

The drug can be adapted to target any strain of Ebola and produced in as little as eight weeks (compared with the months required for ZMapp), Geisbert said, in what he called “plug and play”: sequence any Ebola genome and custom-make a siRNA cocktail.

“There is a need for treatments that can be quickly modified if the strain changes,” he said.

A clinical trial of the new cocktail began last month in Ebola patients in Sierra Leone. A study of an earlier version was partly halted after healthy volunteers developed side effects at high doses. 

Results from human trials with the drug are expected in the second half of this year.

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