Flu codes

name         Richard
status       educator
grade        other
location     N/A

Question -   My students have asked "What to the letters and numbers
mean in the bird flu H5N1?
Are they just a code or do they means anything? If they are a code
how are viruses numbered?"
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 The numbers refer to the types of antigens/proteins that are found on their
surface.  These are proteins that allow the virus to attach and enter the
host cell.  Because there is variety in all proteins and they mutate over
time, there are different versions of each protein.  The N stands for
neuraminidase and the H stands for hemaglutinin.  So H5N1 is a virus that
has the "5th" type of H gene and the "1st" type of N gene.  I don't know if
they are named in the order in which they were discovered.  What scientists
worry about is that more than one of these viruses can inhabit a host cell
at the same time.  If one is the H5N1 version that so far only infects birds
and can't spread from human to human, and another is say H3N2, which is able
to spread between humans are inhabiting the same cell and exchange parts,
the bird flu would be able to spread from person to person.  Viruses mutate
very rapidly and there is nothing that says it WILL do this-it may never
happen.  But it COULD happen, and it is good that the CDC and the WHO are
monitoring the situation and trying to be prepared in case it does.  Here is
a link to a good animation that shows how this process could take place:

http://www.colorado.edu/Outreach/BSI/k12activities/interactive/actidfluanimation.html

vanhoeck
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