Scientists cure Ebola in monkeys

An experimental treatment for Ebola that could potentially save human lives has been shown to be completely effective in monkeys.

If approved for human use it would be the first treatment for the deadly disease, according to Thomas Geisbert, a microbiologist at the US-based National Emerging Infectious Diseases Laboratories Institute.

Ebola virus — which leads to fever, vomiting, diarrhoea and sometimes bleeding — kills up to 90 per cent of infected people. It is transmitted by direct contact with infected blood, body fluids and tissues, and occurs mainly in Sub-Saharan Africa. Although vaccines have been shown to protect monkeys from infection (see Ebola and Marburg vaccine ‘100% effective in monkeys’) no vaccinations or treatments have been approved for humans yet.

The proof-of-concept research, published in The Lancet last week (29 May), describes a new treatment using RNA — a form of genetic material similar to DNA — that targets three viral proteins and interferes with the virus’s lifecycle, preventing it from multiplying.

It builds on previous work by Geisbert’s team that cured guinea pigs infected with the Zaire Ebola virus, the deadliest strain, by giving them the so-called ‘small interfering RNA’ (siRNA).

Now, the team has cured infected rhesus macaque monkeys by giving them seven daily antiviral injections of the siRNA cocktail, with the first injection given half an hour after infection.

But whether this treatment could ever fight Ebola outbreaks in Africa is "a matter of money," Geisbert said. "It’s definitely something that could provide benefit to central Africa, but countries need to push the international agencies they have partnerships with to provide the kinds of funds to get this technology on the shelf."

The rhesus monkeys alone cost more than US$7,000 each, and US$90 to maintain in the laboratory. And more animal studies are needed to determine dosage and safety of treatment in humans.

"We can’t do any treatments on humans so we have to depend on animal work," said Heinz Feldmann of the US National Institute of Allergy and Infectious Diseases, who was not involved in the study.

This kind of treatment is promising, Eric Leroy, virologist at the Gabon-based International Centre for Medical Research in Franceville told SciDev.Net, but incubation time in humans can be as long as 21 days — so any treatment has to work even if given days after infection. He added that "ensuring the total safety of these treatments [in humans] remains to be seen".