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Avian Flu |
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| Avian flu (also "bird flu", "avian influenza", "bird
influenza"), means "flu from viruses |
| adapted to birds", but is sometimes mistakenly used to refer
to both other flu |
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subsets (such as
H5N1 flu) or the viruses that cause them (such as H5N1). |
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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 |
| 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. |
| 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 |
| 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 |
| had a Glu at position 627, while all human influenza viruses
had a
lysine. HA |
| (hemagglutinin):
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 |
| viruses have the ability to bind both types of sialic acid
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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