# 2297
Last winter, for the first time, widespread influenza virus resistance to the antiviral oseltamivir (Tamiflu) was reported . . . first from Norway and then from many other monitoring countries.
You can find earlier coverage of this story here, here, and here.
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.
In some nations, the percentage of H1N1 viruses carrying this mutation has risen to as high as 100%, although most nations are reporting much lower incidences.
Scientists will be watching closely to see if this antiviral resistance is picked up by the H3N2 virus this flu season (which already has become largely resistant to Amantadine).
This story is from the Canadian Press, and is by Helen Branswell - which means that it is clear, concise, expertly written . . . and well worth your time to follow the link and read it in its entirety.
Health officials watching whether flu viruses are becoming resistant to drug
Helen Branswell, THE CANADIAN PRESS
TORONTO - As flu season approaches, public health authorities will be keeping an anxious eye on one family of flu viruses to see if an unwelcome phenomenon that cropped up last winter will stage a repeat performance.
To the surprise and dismay of scientists and governments, H1N1 viruses that were resistant to Tamiflu suddenly appeared in high numbers in Northern Europe.
Testing elsewhere has since shown viruses resistant to the key drug - whose generic name is oseltamivir - have spread to North and South America, the Caribbean, Africa, parts of Asia, Australia and New Zealand.
North American officials say they will quickly test for resistance once the northern hemisphere flu season begins and H1N1 viruses start to spread. And in the U.S. at least, authorities are entertaining the possibility they may have to tweak the advice they give doctors on which flu drugs to use should - as most expect - the problem recur.
"We are thinking about the various sorts of scenarios that might occur," says Dr. Tony Fiori, who develops antiviral drug and vaccine policy in the influenza division of the U.S. Centers for Disease Control in Atlanta, Ga.
"It's hard to imagine we'd be at a point of telling people not to use oseltamivir. We might look at possibilities like pushing people towards using zanamivir when they can, since there hasn't been resistance seen to that."
Zanamivir is the generic name for GlaxoSmithKline's Relenza, which, like Tamiflu, belongs to a class of drugs called neuraminidase inhibitors.
