title: Genome differences among field isolates and vaccine strains of pseudorabies virus.
abstract: The DNA of field isolates and vaccine strains of pseudorabies virus (PRV) was analysed by digestion with the restriction endonuclease BamHI. A number of distinct restriction profiles of the field isolates obtained from different locations within Europe were observed. As for herpes simplex virus, the variations could be classified into two types: first, alterations in the mobility of fragments due to the presence of additional sequences and/or the occurrence of deletions, a phenomenon most apparent in fragments containing part or whole of the repeat sequence of PRV DNA; second, generation of differently sized fragments due to loss and/or gain of restriction endonuclease cleavage sites. By analysis of several strains with BamHI a small number of variable cleavage sites were identified within particular regions of the unique long (UL) segment of the PRV genome. Compared to wild-type PRV, the restriction fragment patterns of vaccine strains showed characteristic alterations, including the absence of bands, which were non-variable in wild-type strains, and/or the presence of new bands some of which were submolar. Some of these characteristics could be explained by a deletion in the unique short (US) region of the genome of most vaccine strains and the occurrence of closely related variants in the uncloned vaccine virus stocks.
authors.forename: A L
authors.initials: AL
authors.lastname: Gielkens
authors.forename: J T
authors.initials: JT
authors.lastname: Van Oirschot
authors.forename: A J
authors.initials: AJ
authors.lastname: Berns
mesh_terms: D004279:DNA, Viral / Q000032:analysis*; D005814:Genes, Viral; D011558:Herpesvirus 1, Suid / Q000235:genetics*; D014765:Viral Vaccines
chemical_list: D004279:DNA, Viral; D014765:Viral Vaccines