Epidemiological and molecular studies on infectious bursal disease virus infection in Luxor province

The infectious bursal disease (IBD) is a continuing serious problem facing poultry industry in Egypt. In this study, 500 bursae samples were collected from different broiler flocks in different localities of Luxor Governorate. The flocks were suffering from mortality and bursal lesions during Dec.2014 to Jan. 2016. The samples were tested by AGPT and the result was 12 flocks only were positive for IBD and then the positive samples were isolated in SPF embryonated chicken eggs. All the inoculated embryos died within 2-3 days. The embryos were smaller than normal, congested with haemorrhagic head, and necrotic foci of liver. Then the presence of virus in embryonated eggs was confirmed by convential PCR. Furthermore, molecular characterization was performed by direct sequencing of a 620-bp cDNA corresponding to the VP2 variable domain of the polyprotein gene synthesized by PCR. With deduced amino acid analysis found that all examined isolates are very virulent strains. four local strains used for nucleotide sequence, percent identity and phylogenetic tree analysis revealed that four isolates (F21,F23,F24,F26) were very close to very virulent old Egyptian strains Giza 2008.