Gene technique for Ebola1st June 2010
An approach known as gene silencing might be able to stop even the most lethal strains of the Ebola virus from infecting people, according to a recent Canadian study.
The researchers say that the approach is the most viable route to treating Ebola.
The technology used to silence genes uses a type of RNA called small interfering RNA (siRNA), which was first recognised by scientists in the late 1990s.
SiRNA molecules are double-stranded, and 20-25 nucleotides long.
They are found in many places in various organisms, where one of their roles is to interfere with RNA and stop the expression of specific genes.
Scientists are just beginning to understand the many roles siRNA plays in the human body, and in 2001 scientists showed that synthetically-produced siRNA was able to silence genes in mammals.
For the purposes of the recent Canadian study, the researchers dosed four rhesus monkeys with synthetic siRNAs developed by various companies.
The researchers wanted to see whether or not the siRNAs could keep the virus from infecting the monkeys for a week.
After a week had elapsed, the researchers wanted to let the monkeys' immune systems take over, in case the animals had developed resistance in the meantime.
Thomas Geisbert, a researcher at Boston University School of Medicine, said that the delivery system was the real key.
Viruses in the Ebola family cause haemorrhagic fever in frightening outbreaks across the African continent, killing both humans and endangered gorilla populations.
The viral strain used for the purposes of the current study comes from the Democratic Republic of Congo, where it kills up to 90% of the people it infects.
There is no such thing as an Ebola vaccine, but the siRNA technique developed by the researchers does block the action of the virus by blocking specific genes in the virus itself.
Geisbert said that he and his team had been confounded when they tried to develop antivirals that would fight Ebola.
In 2006, a research team was able to partially protect some monkeys from being infected with Ebola.
The researchers who wrote the recent study teamed up with the other Ebola researchers, testing the siRNA approach in guinea pigs.
Giesbert said that the problem with testing in guinea pigs was that the viral strain that attacks rodents is very different from the one that attacks people and monkeys.
In the current study, the researchers tested siRNA-based treatments in four monkeys.
The monkeys received daily injections of the siRNA, which saved all of them from extremely potent Ebola infections.
Giesbert said that the siRNA treatment kept the virus from replicating past a certain point for a specified time.
He said that, during that 'containment period,' the immune system had a chance to prepare itself.
Giesbert said that the researchers planned to seek US federal funding for their work.
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