New treatment works against SARS in monkeys
Sun Aug 21, 2005 6:19 PM ET
WASHINGTON (Reuters) - An experimental treatment approach called RNA interference reduced the severity of SARS infections in monkeys, U.S. researchers reported on Sunday.
A tiny Maryland-based biotech company less than a year old said monkeys infected with SARS either before or after treatment became less ill than untreated monkeys.
They believe their approach helps prevent the virus from infecting cells and perhaps also from spreading from cell to cell, they report in the September issue of the journal Nature Medicine.
Severe Acute Respiratory Syndrome, caused by a never-before-seen virus now named the SARS coronavirus, swept China's Guangdong province and then spread globally in 2003. It infected more than 8,000 people and killed around 800 by causing pneumonia and lung failure.
It was contained using quarantine and isolation. But experts fear another outbreak could come at any time and companies are working on vaccines to prevent it and drugs to treat it.
Intradigm, a small spinoff from Swiss drugs giant Novartis, set up business a year ago to develop experimental treatments using small interfering RNAs.
These are short stretches of RNA -- the genetic counterpart of DNA that actually functions in cells -- specifically designed to interfere with certain genes.
They developed two siRNAs, as they are called, to counteract two key genes in the SARS virus known as Spike and ORF1b23.
Working with colleagues in China, they tested their siRNAs in 20 monkeys infected with SARS. Macaque monkeys can be infected with the virus and develop fever and lung damage, but their disease is not as severe as it is in humans.
Patrick Lu of Intradigm and colleagues delivered the siRNA into the noses of half of the monkeys, some before infection with SARS and some afterwards. One group of monkeys was treated with an siRNA that had no activity against SARS.
Those treated developed lower temperatures than untreated or placebo-treated monkeys, although all became sick. "The prophylactic treatment group had the lowest temperature (38.7 C), close to the normal body temperature of Rhesus monkey (38.5 C)," the researchers wrote.
"All animals displayed a loss of appetite and some became agitated and aggressive."
Only 25 percent of the treated monkeys had detectable virus in their throats compared to all the untreated monkeys.
And when the monkeys were killed and their lungs examined, the treated monkeys had fewer infected lung cells, the researchers said.
They said their experiment showed the treatment was safe and could be tested in humans.
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