Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
3378138 | Journal of Microbiology, Immunology and Infection | 2015 | 8 Pages |
PurposeTwo distinguishable subclades of H5N1 (classic and variant strains) are cocirculating among the poultry populations in Egypt despite the intensive vaccination programs. A study to investigate the genetic relationship between avian influenza virus (AIV) isolates from backyard chickens in Sharkia (2009–2011), subclades, and commercially available vaccines was carried out.MethodsForty-eight suspected AIV infected birds were clinically examined and used for virus isolation followed by reverse transcription-polymerase chain reaction. Four H5N1 virus isolates were sequenced and analyzed. The intravenous pathogenicity index (IVPI) of three AIV isolates was determined.ResultsThirty-four hemagglutinating viral agents (30 AIV subtype H5N1 and 4 Newcastle disease virus) were detected. Both the nucleotide and amino acid sequence identities of four H5N1 virus isolates (SHZA-0412/2009, SHZA-0801/2010, SHMK-1903/2010, and SHAH-1403/2011) were high—98.4–99.7% and 100%, respectively—indicative of their genetic homogeneity. The hemagglutinin cleavage site characterization revealed the presence of multiple basic amino acids (–PQRERRRKKR/GL–) of the highly pathogenic phenotype. These results were supported by IVPI in chickens of 2.69–2.90. The similarity of our isolates with H5N1 AIV vaccine strains (93.9–95.1%) was higher than that with H5N2 strains (77.8–91.9%). The divergence of four sequences with classic and variant lineages is 2–2.7% and 2.3–3%, respectively, with two amino acid substitutions (A249P and N251Y).ConclusionGenetic characterization and IVPI data of backyard H5N1 isolates are indicative of a highly pathogenic avian influenza virus with hemagglutinin cleavage site constancy and two amino acids substitutions with Egyptian classic and variant lineages, suggesting a beginning of antigenic drift.