Drastic decrease of transcription activity due to hypermutated long terminal repeat (LTR) region in different HIV-1 subtypes and recombinants.
Transcriptional activation of HIV-1 gene expression is partially controlled by the interaction between viral and cellular transcription factors acting at HIV-1 long terminal repeat (LTR) sequences. HIV-1 subtyping at LTR region and nucleotide LTR variability from clinical samples in 48 subjects carrying different HIV-1 subtypes (9A, 5C, 3D, 3F, 21G, 2H, 3J and 2 undefined) at the protease (PR) gene, were performed. LTR sequences from each HIV-1 clade were cloned in luciferase-expression vectors to determine basal and Tat-induced transcriptional activities in the presence and absence of PMA stimulation. A high number (37.8%) of recombinants at LTR/PR regions were identified. All HIV-1 promoters presented low basal transcriptional activity that was nevertheless induced by Tat and PMA. LTR activity was similar across the majority of HIV-1 variants in response to Tat and cell activation. Only subtype C and CRF01_AE LTRs presented higher basal and induced-PMA transcription activities than HXB2 clade B promoter. No basal or Tat/PMA induced activity was found in those promoters presenting G to A hypermutation compared to the wild type promoter activities. G to A hypermutation at some important transcription binding-factor sites within LTR compromised the activity of the viral promoter, decreasing the in vitro viral transcription of the luciferase gene.
de Arellano
Eva Ramírez
ER
Department of Infectious Diseases, Hospital Carlos III, Madrid, Spain; National Center for Microbiology, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
Alcamí
José
J
López
Marisa
M
Soriano
Vincent
V
Holguín
Africa
A
D000328:Adult; D005260:Female; D015967:Gene Expression Regulation, Viral; D017930:Genes, Reporter; D015756:Genes, tat; D015658:HIV Infections / Q000821:virology*; D016325:HIV Long Terminal Repeat / Q000235:genetics*; D016333:HIV Protease / Q000235:genetics; D015497:HIV-1 / Q000145:classification / Q000235:genetics*; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D016329:Sp1 Transcription Factor / Q000378:metabolism; D013030:Spain; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000235:genetics*
D016328:NF-kappa B; D016329:Sp1 Transcription Factor; D054322:tat Gene Products, Human Immunodeficiency Virus; D008156:Luciferases; D016333:HIV Protease; D013755:Tetradecanoylphorbol Acetate