Replacement of Sublineages of Avian Influenza (H5N1) by Reassortments, Sub-Saharan Africa
Published Date:Nov 2008
Source:Emerg Infect Dis. 14(11):1731-1735.
Keywords:Amino Acid Sequence
Hemagglutinin Glycoproteins, Influenza Virus
Highly Pathogenic Avian Influenza Virus
Influenza A Virus, H5N1 Subtype
Influenza In Birds
Molecular Sequence Data
Description:Eight new full-length sequences from highly pathogenic avian influenza viruses (H5N1) from 4 states in southwest Nigeria were analyzed. All gene sequences were more closely related to the first strains found in Nigeria in 2006 than to any strain found outside the country. Six viruses had evolved by at least 3 reassortment events (AC HA/NS, AC NS) from previously identified sublineages A (EMA 2) and C (EMA 1). Our results suggest that highly pathogenic avian influenza viruses (H5N1) initially imported into Nigeria in 2006 have been gradually replaced by various reassortments. In all reassortants, nonstructural genes were derived from sublineage C with 2 characteristic amino acids (compared with sublineage A). If the high prevalence of reassortants was typical for West Africa in 2007, the absence of such reassortants anywhere else suggests that reintroductions of influenza A (H5N1) from Africa into Eurasia must be rare.
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