Transactivation is a conserved function among primate lentivirus Vpr proteins but is not shared by Vpx.
OBJECTIVE
To investigate the transactivating activity of Vpr proteins from human immunodeficiency viruses types 1 and 2 (HIV-1 and HIV-2) and simian immunodeficiency viruses (SIVs) on various primate lentivirus long terminal repeats (LTRs), and to determine whether the Vpx proteins shared by HIV-2 and SIV are able to transactivate any HIV or SIV promoter.


METHODS
The vpr and vpx genes of the HIVs and SIVs encode virion-associated proteins, which are implicated in viral replication and pathogenesis. HIV-1 Vpr is involved in the transport of the preintegration complex (PIC) to the nucleus, transactivates the viral LTR, and induces cell cycle arrest. HIV-2 and SIV Vpx proteins share amino acid sequence similarities with Vpr and are involved in PIC translocation into the nucleus but are unable to induce cell cycle arrest. We cloned and expressed the vpr and vpx genes from several primate lentiviruses and tested their transactivating ability on HIV-1, HIV-2, SIVmac and SIVagm LTRs cloned upstream of the CAT reporter gene.


RESULTS
All Vpr tested had a transactivating effect on several viral LTRs; however, none of the Vpx proteins showed a detectable transactivating effect.


CONCLUSIONS
These results indicate that the transactivating properties of Vpr proteins were conserved throughout evolution in primate lentiviruses, which suggests that they have an important role in virus replication.
Department of Immunology and Infectious Diseases, Harvard AIDS Institute, Harvard School of Public Health, Boston, Massachusetts 02115-6017, USA.
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Philippon
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Matsuda
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Essex
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D015967:Gene Expression Regulation, Viral; D015696:Gene Products, tat / Q000378:metabolism; D016336:Gene Products, vpr / Q000502:physiology*; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000235:genetics* / Q000378:metabolism; D015498:HIV-2 / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D011323:Primates; D017386:Sequence Homology, Amino Acid; D015302:Simian Immunodeficiency Virus / Q000235:genetics* / Q000378:metabolism; D020079:Terminal Repeat Sequences; D015533:Transcriptional Activation; D054334:Viral Regulatory and Accessory Proteins / Q000502:physiology*; D054322:tat Gene Products, Human Immunodeficiency Virus; D054325:vpr Gene Products, Human Immunodeficiency Virus
D015696:Gene Products, tat; D016336:Gene Products, vpr; C074286:VPX protein, Human immunodeficiency virus 2; C513059:VPX protein, Simian immunodeficiency virus; D054334:Viral Regulatory and Accessory Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus; D054325:vpr Gene Products, Human Immunodeficiency Virus