الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
This study demonstrate the isolation and identification of avian influenza virus from poultry farms suffering from signs of avian influenza in Dakahlia and Dommiat by polymerase chain reaction (PCR) and sequencing and study the effect of formaline and β-propiolactone on immunogenicity and antigenicity of H5N1 AI viruses to assess whether inactivation method is the most suitable choice for influenza virus inactivation and vaccine production. a total of 22 tissue samples either were collected from 22 clinically diseased farms. Isolated virus was identified using different diagnostic methods. Three isolates from two different sub-clades were inactivated by BPL and formalin. inactivated viruses were used for preparation of hyperimmune serum and were tested to determine the specificity of the antibodies produced.Conclusions: We concluded that: Avian influenza H5N1 still circulating in 2010 in Egyptian poultry farms. It cause serious problems either as a single infection (H5N1) or as amixed infection (ND and H5N1).In spite of very rapid AI virus detection (within 15 minutes) by the quick AI detection kits, yet it is of low sensitivity in detection of the virus in field.Cross matching HI test showed that serum produced against BPL inactivated viruses give higher cross reactivity with three viruses than that produced against formalin inactivated viruses. These changes suggest that AI vaccines prepared by formalin inactivation should be carefully done and tested for retaining virus protectivity in the vaccine.Infection with HPAIV H5N1 resulted in significant morbidity and mortality in poultry farms inspite of single or double AI vaccine administration. Constant update of vaccine virus strains are highly required to prevent circulation of different HPAIV H5N1 subclades between poultry farms.