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HN51 |
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Influenza A virus subtype H5N1, also known as
A(H5N1) or simply H5N1 |
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Avian flu (also "bird flu", "avian influenza", "bird
influenza"), means "flu from viruses |
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adapted to birds", but is sometimes mistakenly used to refer
to both other flu subsets |
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(such as
H5N1 flu) or the viruses that cause them (such as H5N1). |
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HPAI A(H5N1) is an avian disease. There is no evidence
of efficient human-to- |
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human transmission or of airborne transmission of HPAI
A(H5N1) to humans. |
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Billions of dollars are being spent researching H5N1 as the
virus is now |
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considered to be the world's largest current pandemic threat |
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In almost all cases, those infected with H5N1 had extensive
physical contact with |
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infected birds. Still, around 60% of humans known to have
been infected with the |
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current Asian strain of HPAI A(H5N1) have died from it, and
H5N1 may |
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mutate or reassort into a strain capable of efficient
human-to-human transmission. |
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In 2003, world-renowned virologist Robert Webster published
an article titled |
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"The world is teetering on the edge of a pandemic that could
kill a |
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large fraction of the human population" in American
Scientist. |
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He called for adequate resources to fight what he sees
as a major world threat. |
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Due to the high lethality and
virulence of HPAI A(H5N1), its endemic presence, its |
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"Bird flu" is a phrase similar to "Swine flu", "Dog flu",
"Horse flu", or "Human flu" |
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in that it refers to an illness caused by any of many
different strains of flu viruses |
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such that the strain in question has adapted to the host.
"Avian flu" differs |
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in being named after an entire vertebrate class with
8,800–10,200 species. |
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All known avian flu viruses belong to the species of virus
called
Influenza A virus. |
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All subtypes (but not all strains of all subtypes) of
Influenza A virus are adapted |
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to birds, which is why for many purposes avian flu virus
is the Influenza |
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A virus (note that the "A" does not stand for
"avian"). |
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Distinguishing between "human
flu viruses" and "avian flu viruses" include
PB2 |
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(RNA
polymerase):
Amino acid (or
residue) position 627 in the PB2 protein |
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encoded by the PB2 RNA
gene. Until
H5N1, all known avian influenza viruses |
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had a Glu at position 627, while all human influenza viruses
had a
lysine. HA |
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Avian influenza HA bind alpha 2-3
sialic acid receptors while |
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human influenza HA bind alpha 2-6 sialic acid receptors.
Swine influenza |
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receptors. |
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Avian flu |
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H5N1 |
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Influenzavirus A |
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Biology and Disease |
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