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By Sharon Begley
NEW YORK, Aug 29 (Reuters) - The experimental Ebola drugZMapp cured all 18 of the lab monkeys infected with the deadlyvirus, including those suffering the fever and hemorrhagingcharacteristic of the disease and just hours from death,scientists reported on Friday.
Even monkeys not treated until five days after infectionsurvived. No other experimental Ebola therapy has ever shownsuccess in primates when given that long after infection; thefive days is analogous to nine to 11 days after infection inpeople.
Although two American aid workers who contracted Ebola inLiberia were cured after receiving ZMapp, their physicians donot know if the drug helped. A Liberian doctor with the diseasedied this week despite being given the drug, as did a Spanishpriest.
ZMapp, produced by San Diego-based Mapp Biopharmaceutical,has never been scientifically tested in people, and the currentstudy was the first in primates. The success is therefore a"monumental achievement," virologist Thomas Geisbert of theUniversity of Texas Medical Branch wrote in a commentary on thepaper, published online in Nature.
There are no approved Ebola vaccines or treatments, buthuman safety trials will begin next week on a vaccine fromGlaxoSmithKline Plc and this autumn on one from NewLinkGenetics Corp.
The Ebola outbreak in West Africa has killed 1,552 peopleout of 3,069 confirmed cases, the World Health Organizationsaid, and is on pace to infect 20,000. Neither governments norprivate medical groups have been able to contain the outbreak,which WHO said will almost certainly continue into 2015.
ZMapp is a mix of three antibodies that bind to proteins onEbola viruses and trigger the immune system to destroy them.Mapp had previously developed two different cocktails ofantibodies, but they protected only 43 percent of monkeys whengiven as late as five days after infection.
For the current study, scientists led by Gary Kobinger ofthe Public Health Agency of Canada set out to identify theoptimal mix of antibodies from the earlier cocktails. His teamtested the antibodies in guinea pigs one at a time and invarious combinations, identifying the two best performers lastDecember.
The two graduated to tests in 12 rhesus monkeys. This springthe winner of that face-off, ZMapp, was given to another 18infected monkeys - three doses at three-day intervals startingthree, four or five days after infection.
All three untreated monkeys, in contrast, died of Ebola byday eight. With ZMapp, even advanced symptoms such as rashes,liver dysfunction and hemorrhaging disappeared, a resultKobinger called "beyond my own expectations."
"This is an extremely encouraging result," said David Evans,professor of virology at England's University of Warwick, whowas not involved in the study.
The success suggests that ZMapp "offers the best option" fortreating Ebola, Kobinger's team wrote, and should be tested forsafety in people to enable its compassionate use "as soon aspossible."
The Ebola strain in the study is the Kikwit variant, not theGuinea strain responsible for the current outbreak. ZMappinhibited replication of the Guinea strain in lab dishes,however, suggesting it might be broadly effective.
Mapp has no more doses of ZMapp, which is produced in theleaves of tobacco plants at Kentucky BioProcessing, a unit ofReynolds American Inc. Greenhouses there began makingmore ZMapp "a couple of weeks ago, but the process takes time,"said Reynolds spokeswoman Maura Payne.
It aims to produce enough for tests necessary to seekregulatory approval of ZMapp, she said, "and we plan to beginthat testing protocol by year-end." (Editing by Matthew Lewis)
