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The rise in Tamiflu resistance among one seasonal flu strain over the past year has intensified concerns over how well our stockpiled Oseltamivir (Tamiflu) and Zanamivir (Relenza) will work during a pandemic.
Both work as neuraminidase inhibitors.
Beginning in late 2007, laboratory analysis of influenza viruses in northern Europe began picking up a small number of resistant samples.
The resistant virus is H1N1, which is only one of several circulating strains of flu viruses. The H3N2 virus, thus far, remains sensitive to the drug, as does the influenza B virus in circulation.
This resistance is caused by a mutation, known as H274Y, where a single amino acid substitution (histidine (H) to tyrosine (Y)) occurs at the neuraminidase position 274.
Since then, the number of resistant H1N1 viruses around the world has risen steeply, approaching 100% of the samples being tested in some regions.
While we can't know what virus will spark the next pandemic, we worry most about the H5N1 bird flu virus. It is circulating in birds, has been detected in 65 countries, and causes high mortality in humans.
Unfortunately, the H5N1 bird flu virus shares a very similar N Protein (neuraminidase) with the now resistant H1N1, which leads many scientists to fear the bird flu virus could acquire resistance rapidly during a pandemic.
This report is from Reuters, and it contains an interview with Dr. Robert G. Webster.
Webster is suggesting that oseltamivir (Tamiflu) and zanamivir (Relenza) be tested in combination with other antivirals like ribavirin and amantadine.
Follow the link to read the article in its entirety.
Experts say new drugs needed to fight flu pandemic
27 Feb 2009 10:56:00 GMT
Source: Reuters
By Tan Ee Lyn
HONG KONG, Feb 27 (Reuters) - Experts on Friday urged governments on Friday to diversify their stockpiles of drugs and called for more new medicines to fight what could be the world's next flu pandemic caused by the H5N1 bird flu virus.
Many advanced countries stock up on oseltamivir and zanamivir, two varieties of the same class of drugs that stops the H5N1 virus from multiplying.
But oseltamivir has proven to be largely useless in fighting the H1N1 seasonal human influenza virus and experts are questioning how well, and how long, the drug would stand up against the H5N1 virus, should it unleash a pandemic.
"We have been extremely foolish on our policies of stockpiling drugs. We have been stockpiling two varieties of the same drug," virologist Robert Webster at the St Jude Children's Hospital in the United States said at a medical conference in Hong Kong.
He said the resistance of the H1N1 virus to oseltamivir was as high as 98 percent worldwide.
"The likely scenario is that the (H5N1) virus will become resistant when you start using more and more (of one) drug, you get resistant (H5N1) mutants," he told Reuters later.
(Continue . . .)
