title: Adeno-associated virus type 2 rep gene-mediated inhibition of basal gene expression of human immunodeficiency virus type 1 involves its negative regulatory functions.
abstract: Adeno-associated virus type 2 (AAV-2), a human parvovirus which is apathogenic in adults, inhibits replication and gene expression of human immunodeficiency virus type 1 (HIV-1) in human cells. The rep gene of AAV-2, which was shown earlier to be sufficient for this negative interference, also down-regulated the expression of heterologous sequences driven by the long terminal repeat (LTR) of HIV-1. This effect was observed in the absence of the HIV-1 transactivator Tat, i.e., at basal levels of LTR-driven transcription. In this work, we studied the involvement of functional subsequences of the HIV-1 LTR in rep-mediated inhibition in the absence of Tat. Mutated LTRs driving an indicator gene (cat) were cointroduced into human SW480 cells together with rep alone or with double-stranded DNA fragments or RNA containing sequences of the HIV-1 LTR. The results indicate that rep strongly enhances the function of negative regulatory elements of the LTR. In addition, the experiments revealed a transcribed sequence element located within the TAR-coding sequence termed AHHH (AAV-HIV homology element derived from HIV-1) which is involved in rep-mediated inhibition. The AHHH element is also involved in down-regulation of basal expression levels in the absence of rep, suggesting that AHHH also contributes to negative regulatory functions of the LTR of HIV-1. In contrast, positive regulatory elements of the HIV-1 LTR such as the NF kappa B and SP1 binding sites have no significant influence on the rep-mediated inhibition.
authors.affiliation: Forschungsschwerpunkt Angewandte Tumorvirologie, Deutsches Krebsforschungszentrum, Heidelberg, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Oelze
authors.forename: K
authors.initials: K
authors.lastname: Rittner
authors.forename: G
authors.initials: G
authors.lastname: Sczakiel
mesh_terms: D001483:Base Sequence; D002478:Cells, Cultured; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics*; D000229:Dependovirus / Q000235:genetics*; D015967:Gene Expression Regulation, Viral; D015696:Gene Products, tat / Q000172:deficiency; D017930:Genes, Reporter; D005814:Genes, Viral / Q000235:genetics*; D016325:HIV Long Terminal Repeat / Q000235:genetics; D015497:HIV-1 / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000235:genetics*; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D004268:DNA-Binding Proteins; D015696:Gene Products, tat; D014764:Viral Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus; C068734:rep proteins, Adeno-associated virus 2