Characterization of pif, a gene required for the per os infectivity of Spodoptera littoralis nucleopolyhedrovirus.
During plaque purification of Spodoptera littoralis nucleopolyhedrovirus in S. littoralis Sl52 cell culture, a deletion mutant virus was isolated. Analysis of the biological properties of this mutant virus revealed an absence of per os infectivity of the occluded virus. Infectivity by injection of the non-occluded (budded) virus is not different between the wild-type and the deleted virus. Restriction analysis of the mutant virus genome revealed a 4.5 kb deletion within the NotI D fragment. The observed phenotype was mapped to the deleted region by rescue experiments. The deletion was characterized and the equivalent DNA fragment on the wild-type virus was sequenced. By co-transfecting the DNA of the deleted virus with plasmids derived from the wild-type virus, it was possible to determine that ORF 7 in this fragment is responsible for the observed phenotype. ORF 7, called pif (per os infectivity factor), is homologous to ORF 119 of Autographa californica nucleopolyhedrovirus. Similar ORFs are present in all sequenced baculoviruses. The product of this gene is an occlusion body-derived virion structural protein required only for the first steps of larva infection, as viruses being produced in cells expressing the gene but not containing it in their genomes are able to produce successful infections.
Kikhno
Iryna
I
Laboratoire de Pathologie Comparée, UMR 5087 INRA/CNRS/Université de Montpellier II, 30380 Saint Christol les Alès, France1.
Gutiérrez
Serafín
S
Laboratoire de Pathologie Comparée, UMR 5087 INRA/CNRS/Université de Montpellier II, 30380 Saint Christol les Alès, France1.
Croizier
Liliane
L
Laboratoire de Pathologie Comparée, UMR 5087 INRA/CNRS/Université de Montpellier II, 30380 Saint Christol les Alès, France1.
Croizier
Guy
G
Laboratoire de Pathologie Comparée, UMR 5087 INRA/CNRS/Université de Montpellier II, 30380 Saint Christol les Alès, France1.
Ferber
Miguel López
ML
Laboratoire de Pathologie Comparée, UMR 5087 INRA/CNRS/Université de Montpellier II, 30380 Saint Christol les Alès, France1.
D000595:Amino Acid Sequence; D000818:Animals; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D017353:Gene Deletion; D005814:Genes, Viral; D007814:Larva / Q000821:virology; D008969:Molecular Sequence Data; D017924:Nucleopolyhedroviruses / Q000235:genetics* / Q000502:physiology*; D016366:Open Reading Frames / Q000235:genetics; D017422:Sequence Analysis, DNA; D018411:Spodoptera / Q000821:virology*; D015678:Viral Structural Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
D015678:Viral Structural Proteins; D015252:Deoxyribonucleases, Type II Site-Specific; C038565:GCGGCCGC-specific type II deoxyribonucleases