title: Selective and nonselective packaging of cellular RNAs in retrovirus particles.
abstract: Assembly of retrovirus particles normally entails the selective encapsidation of viral genomic RNA. However, in the absence of packageable viral RNA, assembly is still efficient, and the released virus-like particles (termed "Psi-" particles) still contain roughly normal amounts of RNA. We have proposed that cellular mRNAs replace the genome in Psi- particles. We have now analyzed the mRNA content of Psi- and Psi+ murine leukemia virus (MLV) particles using both microarray analysis and real-time reverse transcription-PCR. The majority of mRNA species present in the virus-producing cells were also detected in Psi- particles. Remarkably, nearly all of them were packaged nonselectively; that is, their representation in the particles was simply proportional to their representation in the cells. However, a small number of low-abundance mRNAs were greatly enriched in the particles. In fact, one mRNA species was enriched to the same degree as Psi+ genomic RNA. Similar results were obtained with particles formed from the human immunodeficiency virus type 1 (HIV-1) Gag protein, and the same mRNAs were enriched in MLV and HIV-1 particles. The levels of individual cellular mRNAs were approximately 5- to 10-fold higher in Psi- than in Psi+ MLV particles, in agreement with the idea that they are replacing viral RNA in the former. In contrast, signal recognition particle RNA was present at the same level in Psi- and Psi+ particles; a minor fraction of this RNA was weakly associated with genomic RNA in Psi+ MLV particles.
authors: HIV Drug Resistance Program, National Cancer Institute-Frederick, P.O. Box B, Frederick, MD 21702-1201, USA.
authors: Samuel J
authors: SJ
authors: Rulli
authors: Catherine S
authors: CS
authors: Hibbert
authors: Jane
authors: J
authors: Mirro
authors: Thoru
authors: T
authors: Pederson
authors: Shyam
authors: S
authors: Biswal
authors: Alan
authors: A
authors: Rein
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D017931:DNA Primers / Q000737:chemistry; D015683:Gene Products, gag / Q000378:metabolism; D006678:HIV / Q000378:metabolism*; D006801:Humans; D009052:Leukemia Virus, Murine / Q000235:genetics*; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D012367:RNA, Viral / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics* / Q000378:metabolism; D016914:Ribonuclease H / Q000737:chemistry; D014162:Transfection; D019065:Virus Assembly
chemical_list: D017931:DNA Primers; D015683:Gene Products, gag; D012367:RNA, Viral; D016914:Ribonuclease H