H5N2 - Weaker avian flu virus confirmed to change deadly

[Snowy Owl]

Weaker avian flu virus confirmed to change deadly

Japanese researchers have found that a weaker strain of the bird flu virus known as H5N2 can mutate into a deadly one through repeated infections.

http://www.nhk.or.jp/daily/english/03_19.html

Researchers led by Tottori University professor Toshihiro Ito successively infected chicks with the weaker H5N2 variant. The strain was taken from chickens at a poultry farm in Ibaraki Prefecture where the virus was detected in 2005.

The researchers found that the 28th batch of chicks all died after being infected with H5N2. Eight adult chickens injected with the virus also died after several days.

The researchers say the findings show that the weaker strain of the virus turned into a virulent one through repeated infections.

This is the first confirmed case of mutation of an avian flu virus collected from a domestic farm.

Starting in 2005, around 5.8 million chickens were destroyed in Ibaraki prefecture after an outbreak of avian flu caused by the H5N2 strain.

This measure drew criticism from some parties because few birds had died from the infection.

Professor Ito says the mutation occurred earlier than expected. He says the findings underscore the importance of containing any bird flu virus because there is no knowing what sort of mutation could occur at a poultry farm where tens of thousands of birds are kept.
2008/04/03 14:57

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[Allan]

Re: Weaker avian flu virus confirmed to change deadly

Mutation you say? Perhaps. It will be interesting to see the sequences.

[tropical]

Re: Weaker avian flu virus confirmed to change deadly

Mutation you say? Perhaps. It will be interesting to see the sequences.

"The researchers say the findings show that the weaker strain of the virus turned into a virulent one through repeated infections."

Does it in one research (FT old posts) the virus virulence augmented for 1 (milion?) times, after passing through lab mouse reinfections?

[gsgs]

Re: Weaker avian flu virus confirmed to change deadly

> This is the first confirmed case of mutation of an avian flu
> virus collected from a domestic farm.

we saw this LP-->HP in H7 :

Italy 2000
British Columbia 2004
Chile 2003

I don't know whether there are also examples with H5,
but there is a warning from the EU and cullings are
recommended for LP too - because it may convert into HP.

The mechanism how this happens is not so clear,
it's not just a "mutation", but additional base-pairs
have to be included.