WASHINGTON – An experimental drug treatment can help monkeys survive an otherwise deadly infection with a tropical virus called Marburg, which is similar to Ebola, researchers said Wednesday.
The findings in the journal Science Translational Medicine could speed efforts to bring to market a drug treatment against Ebola, a deadly hemorrhagic virus that is sweeping across West Africa in the largest outbreak to date.
There is no available drug or vaccine for Ebola, which has killed 1,350 people and infected 2,473 since March in Sierra Leone, Nigeria, Guinea and Liberia.
Marburg is from the same family as the Ebola virus and also causes severe bleeding, fever, vomiting and diarrhea.
Fatality rates range from 25 percent to 80 percent, and like Ebola, it is transmitted via contact with bodily fluids.
The study tested a Marburg virus drug, made by Canada’s Tekmira Pharmaceuticals, on 16 monkeys.
One group was given the treatment 30-45 minutes after exposure to a lethal dose of the Angola strain of Marburg virus. Other groups were treated one, two and three days following the infection.
“All treated animals in all four studies survived,” said lead author Thomas Geisbert, professor of microbiology and immunology at the University of Texas Medical Branch at Galveston.
– FDA Fast-track –
The control group included monkeys that were sickened with Marburg virus but were not given the treatment. They all died, beginning one week after they were infected.
The discovery that the treatment worked even three days into the monkeys’ infections shows “real world utility of this technology,” Geisbert told reporters.
Experts are hopeful that such a treatment could be useful because symptoms of Marburg virus begin showing themselves around that time.
Ebola, too, usually becomes symptomatic within two to 10 days of infection, though the incubation period can last as long as 21 days.
“The significance of delaying treatment until three days after infection, which is the earliest time at which diagnosis by viral RNA can be detected and those infected show the first clinical signs of disease, is a critical step in triggering clinical interventions,” said Ian MacLachlan, executive vice president and chief technical officer of Tekmira Pharmaceuticals.
The researchers published a study in The Lancet in 2010 that showed the same technology could be used to create a treatment that would completely protect rhesus monkeys against Ebola, Geisbert said.
For it to be deployed for “compassionate use during this outbreak” in people, there would have to be “a situation where a country or someone would request that from the company,” he told reporters.
He added that there were “no problems” in terms of side effects with the doses given in the monkey tests.
Tekmira has begun phase one trials to test safety in people, and in March the company said it was granted a Fast-Track designation by the US Food and Drug Administration to develop its drug, TKM-Ebola.
The drug works by interfering with how Ebolas grows once it penetrates the cells of the body.
Another experimental Ebola drug, ZMapp, works differently, by delivering the body a cocktail of antibodies that target different parts of the Ebola virus.
ZMapp has been given to a handful of people who were sickened in the latest outbreak, including to American missionaries, but it is difficult to make in large amounts.
Geisbert said the Tekmira product could be replicated “relatively quickly,” given the proper funding.
Experts say that getting enough money to pay for trials and development has been a key challenge for drug makers, due the history of sporadic outbreaks in Africa.