GENOMIC RESTRICTION FRAGMENT ANALYSIS OF FOWLPOX-VIRUS VACCINE STRAINAND FIELD ISOLATES USING ECORI, SAL-I AND PST-I RESTRICTION ENDONUCLEASES

Few-pox virus IVRI vaccine strain and 2 field isolates were propagated in chicken-embryo-fibroblast-cell culture and purified by sucrose gra dient ultracentrifugation. Transmission electronmicroscopy revealed th e purified virus showing characteristic fowlpox-virus morphology with bilayer structure and surface tubular elements. The viral DNA was extr acted and analysed after digestion with EcoRI; Sal I and Pst I restric tion endonucleases. EcoRI digestion produced 24 well resolved fragment s with some comigrating fragments and analysis on a seperate gel revea led 40 restriction fragments. Sal I and Pst I digestion revealed a lar ge unresolved fragments with 4 and 18 well resolved fragments respecti vely. The 3 viruses showed similar electrophoretic pattern of DNA rest riction fragments indicating them to be genetically almost similar.