title: The packaging signal of simian immunodeficiency virus is upstream of the major splice donor at a distance from the RNA cap site similar to that of human immunodeficiency virus types 1 and 2.
abstract: Deletion mutation of the RNA 5' leader sequence of simian immunodeficiency virus (SIV) was used to localize the virus packaging signal. Deletion of sequences upstream of the major splice donor (SD) site produced a phenotype most consistent with a packaging defect when analysed by both RNase protection assay and RT-PCR. Sequences downstream of the SD were deleted and produced varying effects but did not affect packaging: a large downstream deletion had little effect on function, whereas a nested deletion produced a profound replication defect characterized by reduced protein production. Secondary structure analysis provided a potential explanation for this. The major packaging signal of SIV appears to be upstream of the SD in a region similar to that of human immunodeficiency virus type 2 (HIV-2) but unlike that of HIV-1; however, the packaging signal of all three viruses are at a similar distance from their respective cap sites. This conserved positioning suggests that it is more important in the virus life cycle than the position of the signal relative to the SD.
authors.affiliation: University of Cambridge Department of Medicine, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK.
authors.forename: P M
authors.initials: PM
authors.lastname: Strappe
authors.affiliation: University of Cambridge Department of Medicine, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK.
authors.forename: J
authors.initials: J
authors.lastname: Greatorex
authors.affiliation: University of Cambridge Department of Medicine, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK.
authors.forename: J
authors.initials: J
authors.lastname: Thomas
authors.affiliation: University of Cambridge Department of Medicine, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK.
authors.forename: P
authors.initials: P
authors.lastname: Biswas
authors.affiliation: University of Cambridge Department of Medicine, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK.
authors.forename: E
authors.initials: E
authors.lastname: McCann
authors.affiliation: University of Cambridge Department of Medicine, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK.
authors.forename: A M L
authors.initials: AML
authors.lastname: Lever
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D022821:RNA Splice Sites; D012367:RNA, Viral / Q000737:chemistry / Q000378:metabolism; D017384:Sequence Deletion; D015302:Simian Immunodeficiency Virus / Q000235:genetics / Q000502:physiology*; D019065:Virus Assembly
chemical_list: D020121:5' Untranslated Regions; D022821:RNA Splice Sites; D012367:RNA, Viral