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Influenzavirus A |
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Influenzavirus A is a genus of a family of viruses
called |
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Orthomyxoviridae in virus classification |
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Influenzavirus A has only one species in it; that species is
called |
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"Influenza A virus". |
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Influenza A virus causes "avian influenza" (also known as
bird flu, |
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avian flu, Influenzavirus A flu, type A flu,
or genus A flu). |
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It is hosted by birds, but may infect several species of
mammals. |
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All known subtypes are endemic in birds. |
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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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"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
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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