title: Trans-inhibition of HIV-1 by a long hairpin RNA expressed within the viral genome.
abstract: BACKGROUND
  Human immunodeficiency virus type 1 (HIV-1) can be inhibited by means of RNA silencing or interference (RNAi) using synthetic short interfering RNAs (siRNAs) or gene constructs encoding short hairpin RNAs (shRNAs) or long hairpin RNAs (lhRNAs). The use of siRNA and shRNA as antiviral therapeutic is limited because of the emergence of viral escape mutants. This problem is theoretically prevented by intracellular expression of lhRNAs generating multiple siRNAs that target the virus simultaneously, thus reducing the chance of viral escape. However, gene constructs encoding lhRNA molecules face problems with delivery to the right cells in an infected individual. In order to solve this problem, we constructed an HIV-1 variant with a 300 bp long hairpin structure in the 3' part of the genome corresponding to the Nef gene (HIV-lhNef).
  
  
  RESULTS
  Intriguingly, HIV-lhNef potently inhibited wild-type HIV-1 production in trans. However, HIV-lhNef demonstrated a severe production and replication defect, which we were able to solve by selecting spontaneous virus variants with truncated hairpin structures. Although these escape variants lost the ability to trans-inhibit HIV-1, they effectively outgrew the wild-type virus in competition experiments in SupT1 cells.
  
  
  CONCLUSIONS
  Expression of the lhNef hairpin within the HIV-1 genome results in potent trans-inhibition of wild-type HIV-1. Although the mechanism of trans-inhibition is currently unknown, it remains of interest to study the molecular details because the observed effect is extremely potent. This may have implications for the development of virus strains to be used as live-attenuated virus vaccines.
authors.affiliation: Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. p.s.konstantinova@amc.uva.nl
authors.forename: Pavlina
authors.initials: P
authors.lastname: Konstantinova
authors.forename: Olivier
authors.initials: O
authors.lastname: ter Brake
authors.forename: Joost
authors.initials: J
authors.lastname: Haasnoot
authors.forename: Peter
authors.initials: P
authors.lastname: de Haan
authors.forename: Ben
authors.initials: B
authors.lastname: Berkhout
mesh_terms: D002460:Cell Line; D002478:Cells, Cultured; D015754:Genes, nef; D016679:Genome, Viral; D015497:HIV-1 / Q000235:genetics* / Q000502:physiology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000821:virology; D034622:RNA Interference; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics*; D011995:Recombination, Genetic; D014779:Virus Replication
chemical_list: D012367:RNA, Viral