Molecular insights of recently circulated Infectious Bursal Disease Virus (IBDV) in broiler chicken in Egypt

IBDV is still one of the most important causes of significant economic losses in poultry industry in Egypt, although implementation of the intensive vaccination programs. A recent increase in IBDV related mortality in most of vaccinated chicken broiler farms in different governorates, prompted to investigate the molecular characters of the circulating IBDV. In present study, 32 bursa samples were assayed in Kaferelsheikh, Menofia, Gharbia and Behera. The virus was isolated by inoculating bursa suspension into embryonated specific pathogen-free (SPF) eggs. CAMs collected and the virus detected by reverse transcriptase-polymerase chain reaction (RT-PCR) for IBDV targeting VP2 gene. Out of the tested samples 20 were positives. Ten IBDV-positive samples were selected for further isolation and characterization. Sequence analysis of PCR products of 10 selected samples was carried out. Eight samples were characterized as very virulent (vvIBDV) and two samples were similar to classical IBDV and vaccine strains. The genotyping of Egyptian vvIBDV indicate progressive evolution of IBDV in Egypt.