title: Impaired RNA incorporation and dimerization in live attenuated leader-variants of SIVmac239.
abstract: BACKGROUND
  The 5' untranslated region (UTR) or leader sequence of simian immunodeficiency virus (SIVmac239) is multifunctional and harbors the regulatory elements for viral replication, persistence, gene translation, expression, and the packaging and dimerization of viral genomic RNA (vRNA). We have constructed a series of deletions in the SIVmac239 leader sequence in order to determine the involvement of this region in both the packaging and dimerization of viral genomic RNA. We also assessed the impact of these deletions upon viral infectiousness, replication kinetics and gene expression in cell lines and monkey peripheral blood mononuclear cells (PBMC).
  
  
  RESULTS
  Regions on both sides of the major splice donor (SD) were found to be necessary for the efficiency and specificity of viral genome packaging. However, stem-loop1 is critical for both RNA encapsidation and dimerization. Downstream elements between the splice donor and the initiation site of SIV-Gag have additive effects on RNA packaging and contribute to a lesser degree to RNA dimerization. The targeted disruption of structures on both sides of the SD also severely impacts viral infectiousness, gene expression and replication in both CEMx174 cells and rhesus PBMC.
  
  
  CONCLUSIONS
  In the leader region of SIVmac239, stem-loop1 functions as the primary determinant for both RNA encapsidation and dimerization. Downstream elements between the splice donor and the translational initiation site of SIV-Gag are classified as secondary determinants and play a role in dimerization. Collectively, these data signify a linkage between the primary encapsidation determinant of SIVmac239 and RNA dimerization.
authors.affiliation: McGill University AIDS Centre, Lady Davis Institute-Jewish General Hospital, Montreal, Quebec, H3T 1E2, Canada. jwhitne2@bidmc.harvard.edu
authors.forename: James B
authors.initials: JB
authors.lastname: Whitney
authors.forename: Mark A
authors.initials: MA
authors.lastname: Wainberg
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002213:Capsid / Q000378:metabolism; D002460:Cell Line; D002522:Chlorocebus aethiops; D019281:Dimerization; D015967:Gene Expression Regulation, Viral; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000821:virology; D008969:Molecular Sequence Data; D012326:RNA Splicing; D012367:RNA, Viral / Q000378:metabolism*; D017384:Sequence Deletion; D015302:Simian Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity* / Q000502:physiology; D019065:Virus Assembly; D014779:Virus Replication
chemical_list: D020121:5' Untranslated Regions; D012367:RNA, Viral