HEALTH 8/22/10 Ebola: Scientists see further step against nightmare virus

[Housecarl]

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Ebola: Scientists see further step against nightmare virus

(AFP) – 16 hours ago

PARIS — US scientists said on Sunday they had cleared a key hurdle in the quest for a drug to treat Ebola, a notorious African virus and feared future weapon of bioterrorism.

A treatment administered to rhesus monkeys within an hour of being infected by the deadliest strain of Ebola was 60 percent effective, and a companion drug was 100-percent effective in shielding cynomolgus monkeys against Ebola's cousin, the Marburg virus.

After studing the findings, the US Food and Drug Administration (FDA) has given the green light for trials on a small group of human volunteers, they said.

Ebola and Marburg are part of a family of so-called filoviruses, which cause haemorrhagic fever -- a disease with mortality rates of up to 90 percent where, in some cases, the patient bleeds to death.

The drugs are in a class of compound called PMO, for phosphorodiamidate morpholino oligomers. They are designed to hamper the virus' replication in cells, thus buying time for the immune system to mount a response and crush the invader.

The research, appearing online in the journal Nature Medicine, was conducted by the US Army Medical Research Institute of Infectious Diseases in collaboration with a Washington-based biotech firm, AVI BioPharma.

The Pentagon pumped funding into research for a vaccine and treatment for Ebola-type viruses in the wake of the September 9 2001 terror attacks on the United States.

Filoviruses are on the list of pathogens such as anthrax that are considered tempting sources for biological warfare or terrorism.

An important step in combatting Ebola was announced in May this year, again using tests on lab monkeys but involving a somewhat different technique to disrupt viral replication.

A team at the US National Emerging Diseases Laboratory Institute at Boston University Medical School designed drugs with small interfering RNAs, or siRNAs, which hamstring reproductive enzymes.

Despite this progress, a long road lies ahead before any treatment is licensed for humans, experts say.

Testing a prototype drug is a three-phase process that starts with a tiny group of volunteers, where it is initially assessed for safety, and then broadens out to successively bigger groups, where effectiveness becomes a parallel question.

According to the UN's World Health Organisation (WHO), about 1,850 cases of Ebola, with some 1,200 deaths, have occurred since 1976.

The virus has a natural reservoir in several species of African fruit bat. Gorillas and other non-human primates are also susceptible to the disease.

Copyright © 2010 AFP. All rights reserved.

 

[Housecarl]

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http://www.independent.co.uk/news/s...fight-against-deadly-ebola-virus-2059361.html

Scientists hail breakthrough in fight against deadly Ebola virus
By Steve Connor, Science Editor
Monday, 23 August 2010

Scientists have developed a new kind of "antisense" drug that has produced promising results in laboratory trials involving the Ebola and Marburg viruses, two of the most lethal known. The drug works by blocking the critical genes that the viruses use to replicate quickly inside the body to give patients valuable time to mount their own immune defence against the viral haemorrhagic fevers.

Tests on laboratory animals have shown that the antisense drugs are effective at fending off Ebola and Marburg, which cause rapid and intense fever and internal bleeding fatal in about 90 per cent of cases.

There are at present no effective treatments or vaccines against either of the viruses, which are highly infectious and have caused particular concern because of the possibility of them being used in biowarfare or as a terrorist weapon. The antisense drugs are composed of short strands of nucleic acids which form a sequence that is complementary or opposite to the nucleic acid sequence found in the genes of the viruses. They work by binding to the viral genes and blocking their action, giving time for the immune defences of the patients to launch an attack on the invading viruses, the scientists said.

The researchers, from the US Army Medical Research Institute of Infectious Diseases (Usamriid), report in the journal Nature Medicine that an antisense drug called AVI-6002 resulted in a survival rate of better than 90 per cent in laboratory mice and guinea pigs exposed to the Ebola virus. When the scientists tested the drug on laboratory monkeys, three out of five survived.

A similar antisense drug, called AVI-6003, proved even more successful against the Marburg virus, with every one of the treated monkeys surviving a viral attack, the study showed.

Ebola and Marburg are considered so dangerous that the research had to be done in special laboratories with the highest security classification, known as biosafety level 4, where the scientists had to wear space-suits and breathe filtered air to protect them as they did their experiments.

The scientists, led by Travis Warren of the Usamriid, believe the results are good enough to warrant clinical trials in humans and the US Food and Drug Administration has given permission to proceed.

The scientists said they have developed "human-grade" antisense drugs that could be used on people after an emergency in 2004, when a laboratory worker in the Usamriid was accidentally pricked in the thumb with a needle while treating Ebola-infected mice. The female worker was isolated, but found to be uninfected, so the human-grade antisense drug was not used on her. But the facility has worked with biotechnology company AVI BioPharma to develop antisense drugs to be used in human clinical trials
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