# 2166
To anyone who has been following the avian influenza story for very long, today's news - that the variant of bird flu that swept through South Korea this spring can infect mammals - isn't exactly earthshaking.
We've seen mammalian H5N1 infections before.
It is a reminder, however, that we are dealing with a species jumping pathogen. And that is always worthy of concern.
A little background follows, then the report from the Korean Times.
The receptor binding domain (RBD) of the H5N1 virus is that area of its genetic sequence that allows it to attach to, and infect, host cells. Much like a key into a padlock, the RBD must `fit' the host cell in order for it to bind.
Different viruses have an affinity for different types of cells. That is why most viruses are selective as to what organ systems they attack, or even what species are susceptible.
This explains why a virus might affect a dog, or a cat, or a bird, yet not affect humans. This species selectivity is known as a `host range'.
Viruses generally have a fairly narrow host range.
The H5N1 virus has shown an ability to infect a surprisingly wide range of hosts. Many species of birds are susceptible, of course. But we've also seen infections in cats (including tigers), dogs, martens, civets, and of course humans.
Researchers have successfully infected cattle with the H5N1 virus, along with ferrets and mice for testing.
It seems the H5N1 virus isn't very particular.
07-22-2008 18:56
`Bird Flu Strain Can Be Transmitted to Mammals'
By Kim Tae-jong
Staff Reporter
Quarantine authorities said Tuesday that the virus strain of avian influenza that swept the country in April could be transmitted to mammals, but not necessarily to humans.
The Ministry of Food, Agriculture, Forestry and Fisheries sent samples from infected birds to the U.S. Center for Disease Control and Prevention for detailed analysis.
The U.S. agency concluded the virus from the sample could be transmitted to mammals but that there was no proof it could infect humans, an official from the ministry said.
``It was impossible to directly test if it can cause illness in humans. Alternatively, we chose a weasel for testing and when it was infected, it showed similar symptoms to bird flu,'' the official said at a news briefing.
He declined a ``yes or no'' answer over the possibility of the virus infecting humans, citing the lack of human testing.
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