H5N3

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H5N3 is a subtype of the species Influenza A virus (sometimes called bird flu virus).

"The antigenic characterization of the AIV found in a dead mallard in Eskilstuna 21 Oct 2005 has been completed at the National Veterinary Institute. 7 dead ducks were found, 4 were tested and one came up positive for bird flu. The virus was identified as H5, the neuraminidase subtype was found to be N3. ***Note: According to the revised International Terrestrial Animal Health Code, all H5 and H7 avian influenza viruses are regarded as "notifiable avian influenza" (NAI). If found highly pathogenic in poultry, they become HPNAI."^[1]

"By using reverse genetics, we prepared an H5N3 vaccine whose hemagglutinin is 99.6% homologous to that of A/CK/HK/86.3/02 (H5N1). We used the internal genes of A/PR/8/34 and the H5 of A/Goose/HK/437.4/99 (H5N1) after deletion of basic amino acids from its connecting peptide region. The resulting virus was not lethal to chicken embryos and grew to high HA titers in eggs, allowing preparation of HA protein-standardized vaccine in unconcentrated allantoic fluid. The N3 neuraminidase, derived from A/Duck/Germany/1215/73 (H2N3), permitted discrimination between vaccinated and naturally infected birds. The virus construct failed to replicate in quail and chickens. Similar to parental A/PR/8/34 (H1N1), it replicated in mice and ferrets and spread to the brains of mice; therefore, it should not be used as a live-attenuated vaccine. The H5N3 vaccine, at doses of 1.2 microg HA, induced HI antibodies in chickens and prevented death, signs of disease, and markedly reduced virus shedding after challenge with A/CK/HK/86.3/02 (H5N1) but did not provide sterilizing immunity. Thus, reverse genetics allows the inexpensive preparation of standardized, efficacious H5N3 poultry vaccines that may also reduce the reemergence of H5N1 genotypes."^[2]

[edit] Sources

1. ^ US gov't website EINet title:Sweden (Eskilstuna): mallard, H5N3 strain confirmed
2. ^ NCBI article Preparation of a standardized, efficacious agricultural H5N3 vaccine by reverse genetics. published September 30, 2003