Cleavage site stability of Egyptian highly pathogenic avian influenza viruses in backyard chickens during 2009-2011.

Purpose: Two 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.

Methods: Forty-eight suspected AIV infected birds were clinically examined and used for virus isolation followed by reverse transcription-polymerase chain reaction.