(Adds details on contract, treatments)
Sept 2 (Reuters) - The U.S. Department of Health and Human Services said on Tuesday a federal contract worth up to $42.3 million would help accelerate testing of an experimental Ebola virus treatment that is being developed by privately held Mapp Biopharmaceutical Inc.
The agency said an initial 18-month contract worth $24.9 million had been approved by its Office of the Assistant Secretary for Preparedness and Response and that the contract could be extended up to a total of $42.3 million
Mapp, based in San Diego, will manufacture a small amount of the drug, called ZMapp, for early stage safety studies and for animal studies needed to prove its effectiveness and safety in people, the agency said in a statement.
The drug, although never tested in humans, won the spotlight earlier this summer when two American aid workers who contracted Ebola in Liberia were cured after receiving it. Their physicians do not know if the drug helped.
ZMapp is a mix of three antibodies manufactured in tobacco plants. It binds to proteins on the Ebola virus and triggers the immune system to destroy them. Mapp previously developed two different cocktails of antibodies, but they protected only 43 percent of monkeys that were given the drug as late as five days after infection.
On Friday, scientists reported that ZMapp had cured all 18 lab monkeys infected with Ebola in one trial, including those suffering fever and hemorrhaging that were hours from death.
"While ZMapp has received a lot of attention, it is one of several treatments under development for Ebola, and we still have very limited data on its safety and efficacy," said Dr. Nicole Lurie, assistant secretary for preparedness and response.
There are no approved Ebola vaccines or treatments, but human safety trials are due to begin this week on a vaccine from GlaxoSmithKline Plc and this autumn on one from NewLink Genetics Corp.
The Ebola epidemic in West Africa could infect more than 20,000 people and spread to more countries, the World Health Organization warned last week. With a fatality rate of 52 percent, the death toll stood at 1,552 as of Aug. 26.
(Reporting by Caroline Humer; Editing by Meredith Mazzilli, Toni Reinhold)