Efficient long-term coexpression of a hammerhead ribozyme targeted to the U5 region of HIV-1 LTR by linkage to the multidrug-resistance gene

Antisense Nucleic Acid Drug Dev. 1997 Oct;7(5):511-22. doi: 10.1089/oli.1.1997.7.511.


Ribozymes as anti-HIV-1 agents hold promise for the treatment of AIDS. They can be delivered into cells either exogenously or through an expression system. For effective protection against HIV-1, sufficient and sustained amounts of the antiviral ribozymes must be delivered into target cells. The coexpression of a dominant selectable marker with ribozymes would serve to enrich for cells containing the molecular antiviral and facilitate prolonged expression of these ribozymes. The multidrug resistance gene (MDR1) is a potential clinically relevant selectable marker and offers many advantages over other known dominant selectable markers, including the use of diverse pharmacologically characterized drug or drug combinations for selection. Harvey sarcoma-based retroviral vectors encoding the MDR1 multidrug transporter with a hammerhead ribozyme targeted to highly conserved sequences within the HIV-1 U5 LTR segment have been constructed in a bicistronic format. The internal ribosome entry site (IRES) from encephalomyocarditis virus was used to initiate translation of the MDR1 mRNA. The ribozyme remained functional despite being tethered to MDR1. Long-term, high-level expression of both the ribozyme and MDR1, as evident by RT-PCR and FACS analysis, was observed in a human T cell line containing the construct selected with vincristine, a cytotoxic substrate for the multidrug transporter.

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics*
  • Cell Line
  • Drug Resistance, Multiple / genetics*
  • Genetic Vectors
  • HIV Long Terminal Repeat*
  • Harvey murine sarcoma virus / genetics
  • Humans
  • RNA, Catalytic / genetics*
  • RNA, Catalytic / metabolism
  • T-Lymphocytes / metabolism


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • RNA, Catalytic