Abstract
Infectious bursal disease virus (IBDV) considers as an economic challenge to the poultry industry. Monitoring of circulated recent Infectious bursal disease virus is very significant in controlling the spreading of disease in Egypt. In this study, we targeting VP2 gene of IBDV in bursal samples from 15 different infected chicken commercial farms in seven Egyptian provinces. reverse transcriptase polymerase chain reaction( RT-PCR) were used for virus detection, 7 out of 15 examined farms of four provinces involving Qalubia, Dahaklia, Sharkia, Gharbiya are positive of IBDV. Isolation of Infectious bursal disease virus was carried out by inoculation on chorioallantoic membrane (CAM) of specific pathogen free embryonated chicken eggs (SPF-ECEs). The infectivity titration of the third passage of IBDV strains was 6.4, 5.6, 5.5 and 5.4 Log10 EID50/0.1ml respectively for Dahaklia, Sharkia, Qaluobia and Gharbiya, then identified by RT-PCR and sequenced. The Neutralization Index of Qaluobia isolate was 3.
In conclusion, a recent Egyptian very virulent Infectious bursal disease virus (vvIBDV) strains antigenically different serotype 1 is circulated and further molecular characterization is required.

Keywords: IBDV; Chicken; CAM; RT-PCR; Egypt