Ebola drug

Ebola drug cures infected monkeys

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An experimental drug has cured monkeys infected with the Ebola virus, US-based scientists have said.

Coloured transmission electron micrograph (TEM) of a number of Ebola viruses

The treatment, known as TKM-Ebola-Guinea, targets the Makona strain of the virus, which caused the current deadly outbreak in West Africa.

All three monkeys receiving the treatment were healthy when the trial ended after 28 days; three untreated monkeys died within nine days.

Scientists cautioned that the drug’s efficacy has not been proven in humans.

At present, there are no treatments or vaccines for Ebola that have been proven to work in humans.

University of Texas scientist Thomas Geisbert, who was the senior author of the study published in the journal Nature, said: “This is the first study to show post-exposure protection… against the new Makona outbreak strain of Ebola-Zaire virus.”

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

Gene blocking

Mr Geisbert said the drug, produced by Tekmira Pharmaceuticals, could be adapted to target any strain of Ebola and could be manufactured in as little as eight weeks.

It works by blocking particular genes, which stops the virus replicating.

The two-month production time compares with the several months needed to make ZMapp – another experimental drug, which cured monkeys with a different strain of Ebola than the one in the current outbreak.

Since March 2014, more than 10,602 people have been reported as having died from the disease in six countries – Liberia, Guinea, Sierra Leone, Nigeria, the US and Mali.

The total number of reported cases is more than 25,556.

It has been the deadliest occurrence of Ebola since its discovery in 1976.

Scientists Find Potential Ebola Drug Target in Breakthrough Study .

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WASHINGTON: Interfering with the replication of the Ebola virus can stop it in its tracks, opening the door to potential treatments for the deadly disease, scientists say.

Scientists have found that a protein made by the virus plays a role similar to that of a coat-check attendant.

The protein removes a protective coat from the virus’s genetic material, exposing the viral genome so that it can be copied, and then returns the coat, according to a new study led by scientists at Washington University School of Medicine in St Louis.

The research, in cell cultures, showed that interfering with this process kills the virus.

As part of the study, the researchers introduced rogue coat-check attendants into Ebola-infected cells. These rogue attendants carried a short chain of amino acids that forms the part of the protein that removes the coat.

But they lacked the ability to return the coat, disrupting the emergence of newly created viruses from infected cells. Consequently, the virus did not survive.

“This coat-check protein, known as VP35, has a great deal of potential as a new target for Ebola treatments,” said senior author Gaya Amarasinghe.

“If we can block this process, we can stop Ebola infection by blocking viral replication,” said Amarasinghe.

The Ebola outbreak that began last year in West Africa has infected nearly 25,000 people and killed more than 10,000, according to the Centres for Disease Control and Prevention.

Amarasinghe, first author Daisy Leung and colleagues have spent the past seven years studying the role of VP35, a viral protein involved in the replication process.

The researchers showed that VP35 binds to the virus’s nucleoprotein – which forms part of the protective coat worn by the virus’ RNA. They found that this binding removes the nucleoprotein from the viral RNA prior to replication.

And while the viral RNA is being copied, VP35 keeps newly synthesised nucleoproteins from attaching to other RNA in the host cell.

New copies of the virus require new protein coats. So VP35 also ensures that new nucleoproteins – made by the host cell’s protein-making machinery – bind only to Ebola RNA, allowing the virus to complete replicating.

Disabling or disrupting VP35 could stop the virus in its tracks, according to Amarasinghe.

Ebola drug ‘100% effective’ in monkey trials.

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The experimental Ebola drug ZMapp cured all 18 of the lab monkeys infected with the virus, including those suffering the fever and haemorrhaging characteristic of the disease and just hours from death, scientists have said.

Even monkeys not treated until five days after infection survived, the scientists, who published their data in the journal Nature on Friday, said.

No other experimental Ebola therapy has ever shown success in primates when given that long after infection; the five days is analogous to nine to 11 days after infection in people.

Although two American aid workers who contracted Ebola in the West Afrucan nation of Liberia were cured after receiving ZMapp, their physicians do not know if the drug helped.

A Liberian doctor with the disease died this week despite being given the drug, as did a Spanish priest.

ZMapp, produced by San Diego-based Mapp Biopharmaceutical, has never been scientifically tested in people, and the current study was the first in primates.

The success is therefore a “monumental achievement,” virologist Thomas Geisbert of the University of Texas Medical Branch wrote in a commentary on the paper, published online in Nature.

There are no approved Ebola vaccines or treatments, but human safety trials will begin next week on a vaccine from GlaxoSmithKline Plc and this autumn on one from NewLink Genetics Corp.

The Ebola outbreak in West Africa has killed 1,552 people out of 3,069 confirmed cases, the World Health Organisation said.

The agency said the disease was on pace to infect 20,000 people. Neither governments nor private medical groups have been able to contain the outbreak, which WHO said will almost certainly continue into 2015.

Optimal mix

ZMapp is a mix of three antibodies that bind to proteins on Ebola viruses and trigger the immune system to destroy them.

ZMapp had previously developed two different cocktails of antibodies, but they protected only 43 percent of monkeys when given as late as five days after infection.

For the current study, scientists led by Gary Kobinger of the Public Health Agency of Canada set out to identify the optimal mix of antibodies from the earlier cocktails.

His team tested the antibodies in guinea pigs one at a time and in various combinations, identifying the two best performers last December.

The two graduated to tests in 12 rhesus monkeys. This spring the winner of that face-off, ZMapp, was given to another 18 infected monkeys – three doses at three-day intervals starting three, four or five days after infection.

All three untreated monkeys, in contrast, died of Ebola by day eight. With ZMapp, even advanced symptoms such as rashes, liver dysfunction and haemorrhaging disappeared, a result Kobinger called “beyond my own expectations”

“This is an extremely encouraging result,” said David Evans, professor of virology at England’s University of Warwick, who was not involved in the study.

The success suggests that ZMapp “offers the best option” for treating Ebola, Kobinger’s team wrote, and should be tested for safety in people to enable its compassionate use “as soon as possible”.