title: Nonreciprocal packaging of human immunodeficiency virus type 1 and type 2 RNA: a possible role for the p2 domain of Gag in RNA encapsidation.
abstract: The ability of human immunodeficiency virus types 1 (HIV-1) and 2 (HIV-2) to cross-package each other's RNA was investigated by cotransfecting helper virus constructs with vectors derived from both viruses from which the gag and pol sequences had been removed. HIV-1 was able to package both HIV-1 and HIV-2 vector RNA. The unspliced HIV-1 vector RNA was packaged preferentially over spliced RNA; however, unspliced and spliced HIV-2 vector RNA were packaged in proportion to their cytoplasmic concentrations. The HIV-2 helper virus was unable to package the HIV-1 vector RNA, indicating a nonreciprocal RNA packaging relationship between these two lentiviruses. Chimeric proviruses based on HIV-2 were constructed to identify the regions of the HIV-1 Gag protein conferring RNA-packaging specificity for the HIV-1 packaging signal. Two chimeric viruses were constructed in which domains within the HIV-2 gag gene were replaced by the corresponding domains in HIV-1, and the ability of the chimeric proviruses to encapsidate an HIV-1-based vector was studied. Wild-type HIV-2 was unable to package the HIV-1-based vector; however, replacement of the HIV-2 nucleocapsid by that of HIV-1 generated a virus with normal protein processing which could package the HIV-1-based vector. The chimeric viruses retained the ability to package HIV-2 genomic RNA, providing further evidence for a lack of reciprocity in RNA-packaging ability between the HIV-1 and HIV-2 nucleocapsid proteins. Inclusion of the p2 domain of HIV-1 Gag in the chimera significantly enhanced packaging.
authors.affiliation: Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 2QQ, United Kingdom. jfk11@mole.bio.cam.ac.uk
authors.forename: J F
authors.initials: JF
authors.lastname: Kaye
authors.forename: A M
authors.initials: AM
authors.lastname: Lever
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D015683:Gene Products, gag / Q000502:physiology*; D015497:HIV-1 / Q000502:physiology*; D015498:HIV-2 / Q000502:physiology*; D008969:Molecular Sequence Data; D011533:Proviruses / Q000502:physiology; D012367:RNA, Viral / Q000502:physiology*; D019065:Virus Assembly
chemical_list: D015683:Gene Products, gag; D012367:RNA, Viral