Human immunodeficiency virus type 1 negative factor is a transcriptional silencer.
The negative factor (nef) of human immunodeficiency virus (HIV) type 1 acts to down-regulate virus replication. To decipher the step in the virus life cycle affected by nef, functional proviral clones with (pHIV F-) or without (pHIV F+) a deletion mutation in the nef gene were constructed. In CD4+ cells, 30- to 50-fold more virus was produced over the course of 18-20 days with cultures infected with F- compared to F+ virus. In CD4- cell lines, 2- to 10-fold greater virus production was found from cultures transfected with pHIV F- than those transfected with pHIV F+. The negative regulatory effects of nef on pHIV F- could be supplied in trans with a plasmid expressing only the nef gene product. Virus produced by COS-1 cells transfected with pHIV F- or pHIV F+ showed similar binding, uptake, uncoating, and reverse transcription. Analysis of HIV-1 RNA and structural protein levels and rates of viral RNA synthesis in CD4- cells also showed 2- to 10-fold higher levels in cells transfected with pHIV F- compared to pHIV F+. The activity of a HIV-1-chloramphenicol acetyltransferase (CAT) plasmid was also suppressed by nef, whereas other CAT plasmids were unaffected. These findings demonstrate that nef acts as a specific silencer of HIV-1 transcription. This activity may be critical for maintenance of HIV-1 latency in vivo.
Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110.
T M
TM
Niederman
B J
BJ
Thielan
L
L
Ratner
D000818:Animals; D002460:Cell Line; D015693:Gene Products, nef; D005796:Genes; D005809:Genes, Regulator; D005814:Genes, Viral; D015497:HIV-1 / Q000235:genetics* / Q000254:growth & development; D006801:Humans; D007700:Kinetics; D009693:Nucleic Acid Hybridization; D012191:Retroviridae Proteins / Q000235:genetics*; D013489:Suppression, Genetic; D014158:Transcription, Genetic; D014162:Transfection; D014779:Virus Replication; D054311:nef Gene Products, Human Immunodeficiency Virus
D015693:Gene Products, nef; D012191:Retroviridae Proteins; D054311:nef Gene Products, Human Immunodeficiency Virus