Giuseppe
Emeritus
Antigenic and genetic characteristics of Influenza A(H5N1) viruses and candidate vaccine viruses developed for potential use in human vaccines (WHO, extract, 9/24/09, edited)
[Source Full Document: LINK. EDITED.]
Antigenic and genetic characteristics of Influenza A(H5N1) viruses and candidate vaccine viruses developed for potential use in human vaccines
September 2009
Since their reemergence in 2003, influenza A(H5N1) influenza viruses have become endemic in some countries and continue to cause outbreaks in poultry and sporadic human infections. Despite the emergence of the pandemic A(H1N1) 2009 virus, the zoonotic and pandemic threats posed by H5N1 viruses remain.
The H5N1 viruses have continued to diversify both genetically and antigenically leading to the need for multiple candidate vaccine viruses. The development of representative H5N1 candidate vaccine viruses, coordinated by the World Health Organization (WHO), remains an essential component of the overall global strategy for pandemic preparedness. This summary provides an update on the characterization of H5N1viruses isolated from birds and humans, and the current status of the development of candidate H5N1 vaccine viruses.
Comparisons of the candidate H5N1 vaccine viruses with respect to immunogenicity and their relationship to newly emerging H5N1 viruses are ongoing, and will be updated periodically by WHO. An update of current and completed H5N1 vaccine clinical trials
can be found at http://www.who.int/vaccine_research/diseases/influenza/flu_trials_tables/en/index.html
Influenza A(H5N1) activity from February to September 2009
A(H5N1) viruses have continued to be detected in birds in Africa and Asia. Human infections have been reported to WHO from China, Egypt and Viet Nam, countries that have also declared outbreaks in birds (Table 1).
Antigenic and genetic characteristics.
A nomenclature for phylogenetic relationships among the haemagglutinin (HA) genes of H5N1 viruses was devised in consultation with representatives of FAO, OIE and WHO. This nomenclature is updated when novel genetic clades emerge and can be found at http://www.who.int/csr/disease/avian_influenza/guidelines/nomenclature/en/index.html
Viruses characterized during this period fall within the following clades:
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[Source Full Document: LINK. EDITED.]
Antigenic and genetic characteristics of Influenza A(H5N1) viruses and candidate vaccine viruses developed for potential use in human vaccines
September 2009
Since their reemergence in 2003, influenza A(H5N1) influenza viruses have become endemic in some countries and continue to cause outbreaks in poultry and sporadic human infections. Despite the emergence of the pandemic A(H1N1) 2009 virus, the zoonotic and pandemic threats posed by H5N1 viruses remain.
The H5N1 viruses have continued to diversify both genetically and antigenically leading to the need for multiple candidate vaccine viruses. The development of representative H5N1 candidate vaccine viruses, coordinated by the World Health Organization (WHO), remains an essential component of the overall global strategy for pandemic preparedness. This summary provides an update on the characterization of H5N1viruses isolated from birds and humans, and the current status of the development of candidate H5N1 vaccine viruses.
Comparisons of the candidate H5N1 vaccine viruses with respect to immunogenicity and their relationship to newly emerging H5N1 viruses are ongoing, and will be updated periodically by WHO. An update of current and completed H5N1 vaccine clinical trials
can be found at http://www.who.int/vaccine_research/diseases/influenza/flu_trials_tables/en/index.html
Influenza A(H5N1) activity from February to September 2009
A(H5N1) viruses have continued to be detected in birds in Africa and Asia. Human infections have been reported to WHO from China, Egypt and Viet Nam, countries that have also declared outbreaks in birds (Table 1).
Antigenic and genetic characteristics.
A nomenclature for phylogenetic relationships among the haemagglutinin (HA) genes of H5N1 viruses was devised in consultation with representatives of FAO, OIE and WHO. This nomenclature is updated when novel genetic clades emerge and can be found at http://www.who.int/csr/disease/avian_influenza/guidelines/nomenclature/en/index.html
Viruses characterized during this period fall within the following clades:
- Clade 2.2 viruses were detected in chickens in Bangladesh and their genetic characteristics were similar to those of viruses circulating in Bangladesh during 2008 (Figure 1). Data are not available on the antigenic properties of these viruses.
- Clade 2.2.1 viruses continue to circulate in poultry in Egypt with sporadic transmission to humans. Viruses isolated during this period were genetically similar to those isolated during 2007 and 2008 (Figure 1). Data are not available on the antigenic properties of the 2009 viruses.
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