Some Molecular Studies on Infectious Bursal Disease Virus

Abstract

In the present study efforts were conducted in order to identify the correlation between some commercially used vaccinal strains and local isolates of IBDV at the molecular level ofboth antigenic and genomic structure. Briefly both vaccinal strains (D78 and Bursa Vac.) and local isolates, (Local 1 and Local 2) were propagated in vero cell culture for three passages and titrated. Titers were 4.3, 3.6, 3.6, and 6.1 log1 0 TCIDsolml for D78, B.V., locall and Local2 respectively and confirmed by using Dot Immuno-Blot Assay (DIA). The genomic dsRNA ofiBDVs were extracted and analyzed by agarose gel electrophoresis to detect variations in size of the dsRNA genome of IBDV.The sizes determined by agarose gel electrophoresis were similar for the tested strains and were about 3.1 kilo base for segment A and 2.8 kilo base for segment B. Reverse Transcription/ polymerase Chain Reaction (RT/PCR) was•. conducted to amplify a 643 base pair fragment covering the hyper variable region of VP2 gene, by analysis of the amplified product using . agarose gel electrophoresis. We estimated the amplified fragment to be of the expected size without significant differences between the strains indicating no nucleotides deletion or insertion at this region of the VP2 gene. Restriction Fragment Length Polymorphism (RFLP) using the restriction enzymes Mboi and BstXl for the PCR product were done to compare the polymorphism of the fragments obtained by digestion using these enzymes.