Tuesday, July 14, 2009

Nature Pub.: In vitro and in vivo characterization of new swine-origin H1N1 influenza viruses

[You can find this document at the site. Click on the title of this post.]

Excerpt:

On 11 June 2009 the World Health Organization declared
that the infections caused by the new strain had reached pandemic
proportion.

Characterized as an influenza A virus of the H1N1
subtype, the genomic segments of the new strain were most closely
related to swine viruses1. Most human infections with swine origin
H1N1 influenza viruses (S-OIVs) seem to be mild; however,
a substantial number of hospitalized individuals do not have
underlying health issues, attesting to the pathogenic potential of
S-OIVs. To achieve a better assessment of the risk posed by the new
virus, we characterized one of the first US S-OIV isolates,
A/California/04/09 (H1N1; hereafter referred to as CA04), as well
as several other S-OIV isolates, in vitro and in vivo. In mice and
ferrets, CA04 and other S-OIV isolates tested replicate more efficiently
than a currently circulating human H1N1 virus.

In addition, CA04 replicates efficiently in non-human primates, causes
more severe pathological lesions in the lungs of infected mice,
ferrets and non-human primates than a currently circulating
human H1N1 virus, and transmits among ferrets.

In specific pathogen-free miniature pigs, CA04 replicates without clinical
symptoms.

The assessment of human sera from different age
groups suggests that infection with human H1N1 viruses antigenically
closely related to viruses circulating in 1918 confers neutralizing
antibody activity to CA04.

Finally, we show that CA04 is sensitive to approved and experimental antiviral drugs, suggesting that these compounds could function as a first line of defence
against the recently declared S-OIV pandemic.

-snip-

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