Increasing genetic heterogeneity of A(H1N1) pandemic influenza virus detected by WHO (10/08/10, extracts, edited)

[Giuseppe]

[Text compiled by the Mod.(IOH). Edited.]

Source:

Weekly epidemiological record
Relev? ?pid?miologique hebdomadaire

8 OCTOBER 2010, 85th YEAR / 8 OCTOBRE 2010, 85e ANN?E
No. 41, 2010, 85, 401?412
http://www.who.int/wer

Full PDF Document: http://www.who.int/wer/2010/wer8541.pdf
Full text, edited: http://www.flutrackers.com/forum/showpost.php?p=374099&postcount=1


Recommended viruses of influenza vaccines for use in the 2011 influenza season (southern hemisphere) - September 2010

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Antigenic and genetic characteristics of recent isolates

Influenza A(H1N1) viruses

The vast majority of A(H1N1) viruses detected worldwide during this period were pandemic A(H1N1); only a small number of seasonal A(H1N1) viruses were confirmed.

Haemagglutination inhibition (HI) tests using postinfection ferret antisera indicated that pandemic A(H1N1) viruses remained antigenically homogeneous and closely related to the vaccine virus A/California/7/2009.

Sequence analysis of pandemic A(H1N1) viruses indicated increasing genetic heterogeneity. A small number of viruses showed reductions in reactivity in HI assays with some ferret antisera raised against a panel of representative viruses including the vaccine virus, but they did not form distinct genetic subclades.

The small number of seasonal A(H1N1) viruses, from China, were generally antigenically and genetically closely related to A/Brisbane/59/2007.

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