Isolation and characterization of mutants of pseudorabies virus with deletion in the immediate-early regulatory gene.
Pseudorabies virus (PrV) immediate-early regulatory protein (IE180) is a potent and promiscuous activator of viral and cellular gene transcription. A mutant with deletion in the IE180 gene is expected to be useful for elucidating the functions of IE180. In this study, we constructed such mutants. Initially, transformants that express IE180 were established from PK-15 and Vero cells by transfection with the IE180 gene of the wild-type PrV. Two types of the deletion mutant could be obtained by using those transformants. One type was the deletion mutant, represented by AY64, in which the IE180 gene was replaced by insertion of the modified Escherichia coli lacZ gene, which was inserted under the control of the IE180 promoter. The other type, represented by AY1030, was a mutant produced from the former type by subsequent deletion of the lacZ gene. The deletion mutants of both types could replicate in the transformants with the IE180 gene, but not in the parent cells. On the other hand, the lacZ gene in AY64 was functional under the control of the IE180 promoter and could express beta-galactosidase (beta-gal) in not only the transformants but also the parent cells, indicating that the IE180 promoter of the mutants can fulfill the intended function in inoculated cells. The parent cells infected with the AY64 expressed only beta-gal, but neither infectious virus nor viral products relating to PrV. The deletion mutants constructed in this study appeared to provide a helpful model for investigating the functions of the IE180-homologs of other herpesviruses as well as IE180 itself, since PrV has only one IE gene. The applicability of the deletion mutants as a useful and safe vector for the introduction of foreign genes into various cells and animals was discussed.
Yamada
S
S
Second Research Division, National Institute of Animal Health, Tsukuba Science City, Ibaraki, Japan.
Shimizu
M
M
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D004926:Escherichia coli; D017353:Gene Deletion; D017781:Genes, Immediate-Early / Q000235:genetics / Q000502:physiology*; D005809:Genes, Regulator / Q000235:genetics / Q000502:physiology*; D000882:Haplorhini; D011558:Herpesvirus 1, Suid / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D007763:Lac Operon; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000502:physiology; D013552:Swine; D014709:Vero Cells