Four sequences are the representative of all clones with identical mutations. RNA (Hough and Bass, 1994;Kim et al., 1994;O’Connell and Keller, 1994;Patterson and Samuel, 1995). This has a number of effects. The A-to-I substitution affects pre-mRNA splicing by changing the splicing site and decreases the binding of RNA to protein resulting in functional changes of the protein (Bass, 2002;Samuel, 2003). Furthermore, during mRNA translation, Inosine is recognized as Guanosine and therefore it incorporates incorrect amino acid sequence (Bass, 2002;Samuel, 2003). Because of these pluripotent properties of ADAR1, it disrupts replication of a number of RNA viruses. ADAR1 inhibits replication of hepatitis delta computer virus by editing of adenosine to inosine in pre-mRNA of hepatitis delta computer virus which eventually affects splicing of untranslated regions (Patterson and Samuel, 1995;Polson, Bass, and Casey, 1996;Sato, Wong, and Lazinski, 2001). ADAR1 was also known to edit double-stranded RNA found in the measles computer virus, which inhibited computer virus assembly and release from cells, leading to a persistent Sodium dichloroacetate (DCA) contamination and development of fatal neuropathic measles contamination (Horikami and Moyer, 1995).Taylor,et al.(2005)showed that ADAR1-induced viral RNA editing inhibited Hepatitis C viral replication (Taylor et al., 2005). Recently Suspeneet al.(Suspene et al.) have shown ADAR1 induced mutation in seasonal influenza and attenuated measles viruses. Since HIV-1 genome has several putative double stranded secondary RNA structures throughout its genome, HIV-1 RNA was considered a potential target for ADAR1. Therefore, in this report we investigated the antiviral effect of ADAR1 on HIV-1. We provided evidence that ADAR1 inhibited HIV-1 protein synthesis and viral infectivity in a variety of cells and against HIV-1 of different tropisms and different clades. We further exhibited that such antiviral activity was at the post transcriptional stage of HIV-1 replication and that ADAR1-induced mutation at therevandenvRNA may be responsible for such posttranscriptional inhibition of viral protein synthesis. In elucidating the mechanism of ADAR1 induced inhibition of HIV-1 protein synthesis we found that ADAR1 induced A-to-G mutations inrevinhibited its transport activity of primary transcriptsgag, polandenvfrom the nucleus to cytoplasm and thereby inhibited viral protein synthesis without any effect on viral RNA synthesis. ADAR1induced mutations in theenvgene further attenuate viral infectivity. == Results == == ADAR1 inhibits HIV-1 protein synthesis and viral infectivity == In order to evaluate the effect of ADAR1 on HIV-1 production, 293T cells were co-transfected with 0.1g pNL4.3 HIV-1 DNA and different amount of ADAR1 DNA. In each transfection assay (this one and subsequent ones), cells were also Sodium dichloroacetate (DCA) co-transfected with a luciferase-expressing plasmid DNA to control transfection efficiency. The expression of ADAR1 p150 from transfected ADAR1 DNA was analyzed by Western Blot and normalized against -actin loading control to show the relative intensity of ADAR1 p150 expression (Supplemental Physique 1A). Following 48 h of transfection, viral protein synthesis was quantified by measuring HIV-1 p24 in culture supernatant and intracellular HIV-1 p24 Rabbit polyclonal to HERC4 production in a cell extract by ELISA. Sodium dichloroacetate (DCA) ADAR1 inhibited extracellular (Physique 1A) and intracellular (Physique 1B) HIV-1 p24 production in a dose dependent manner. With 0.7g of ADAR1 containing plasmid there was an 8 fold reduction of extracellular HIV-1 p24 production in culture supernatant as compared to control plasmid pcDNA. The Sodium dichloroacetate (DCA) inhibition of viral protein synthesis was not due to cellular toxicity by ADAR1 as evidenced by no change in viable cell numbers in the presence and absence of ADAR1 (MTT assay, data not shown). The antiviral activity of ADAR1 was further evaluated in two other cell lines, Jurkat T and HeLa cells. Inhibition of viral p24 production in culture supernatant (Physique 1C) and intracellular p24 (data not shown) was also observed in Jurkat T cells and in HeLa cells (data not shown). == Physique 1. Effect of.
Four sequences are the representative of all clones with identical mutations