الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 123 |  |  |
| | | from | 123 | | |
Abstract
The present research work was taken up with the objectives of molecular characterization of IBDV original isolate in addition to chicken egg and Vero cell culture adapted virus by RT-PCR.Ten bursal samples were collected from the IBD infected birds in Damietta Governorate showing enlarged and hemorrhagic bursae. Bursal homogenates were used for ten-day-old embryonated SPF eggs inoculation via the dropped chorioallantoic membrane (CAM) route and Vero cell culture.Confirmatory tests included VN and FAT tests showing positive reactions for IBDV antigen. Propagation of the obtained isolate in ECE and Vero cells for 10 passages revealed gradual increase in the virus titer up to8log10EID50/ml and 7.5log10TCID50/ml respectively.Distinct CPE was characterized by rounding and clumping of cells was first observed by 96 hours PI at first and second passage level. At fifth passage, increased rounding and clumping of cells, extensive cytoplasmic granularity, marked detachment of cells from surface monolayer and cellular degeneration leading to formation of plaques were recorded by 96 hours PI. At sixth passage level, CPE was characterized by degenerative changes involving more than 80 percent cells and extensive detachment of cells at 96 hours PI.Original, egg adapted, cell culture adapted and bursavac samples were used for viral RNA extraction using Trizol reagent. RT-PCR was performed for all the RNA samples using V1 and V2 pair of primers specific to hyper variable region of VP2 gene for confirming the presence of IBDV in cell culture. Viral RNA extracted from all samples resulted in generation of a targeted amplicon of 472 bp confirming that there were no differences between any of them.