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Objective: The development of a human immunodeficiency virus (HIV)–1 promoter reporter system is critical for investigating transcription activity of the virus. We designed a modified overlap extension PCR method for single round site-directed mutagenesis of the long terminal repeat (LTR) segment of HIV-1. Methods: The procedure consists of overlap extension PCR, DpnI digestion, and product transformation. Wild-type and serial sequence deletion clones of HIV-1 LTR were constructed. Basal transcription activity was also measured. Results: The overall efficiency for obtaining the desired products was 53.2%. The reporter assay indicated the importance of the second NF-ĸB cis-element and surrounding regions in mediating the regulation of HIV-1 transcription. Conclusion: The technique we investigated is suitable for highthroughput functional studies of virus-host interaction.

Objective: To explore whether expression of dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) and reactivation of human immunodeficiency virus type 1 (HIV-1) provirus in dendritic cells (DCs) occur through similar or common signaling pathways. Methods: Phorbol 12-myristate 13-acetate (PMA)–differentiated THP-1 cells were used as the in vitro model of DCs. The activation of the DC-SIGN promoter and HIV-1 5′long-term repeat (LTR) sequence induced by interleukin 4 ( IL-4 ) in differentiated THP-1 cells was studied using luciferase reporter plasmids. The regulatory signaling pathways were identified using specific inhibitors, and the activity of the DC-SIGN promoter and HIV-1 5′LTR was detected. Results: HIV-1 5′LTR was activated by IL-4 –induced signaling pathways but much weaker than DC-SIGN promoter. IL-4 –induced activation of HIV-1 5′LTR was mainly through the nuclear factor kappa-light-chain-enhancer of activated B cells ( NF-κB) pathway, which was also involved in activation of the DC-SIGN promoter. The extracellular signal-regulated kinase (ERK) pathway, which was the main pathway for DC-SIGN promoter activation, also played an important role in HIV-1 5′LTR activation. Conclusion: Our study suggests that the activation of the DC-SIGN promoter and HIV-1 5′LTR may share NF-κB and ERK-signaling pathways. * HIV-1 : human immunodeficiency virus type 1; cDNA : complementary DNA; DCs : dendritic cells; LTR : long-term repeat; NF-κB : nuclear factor-kappa B; Sp-1 : stimulatory protein 1; AP-1 : activator protein 1; NF-AT : nuclear factor of activated T cells; DC-SIGN : dendritic cell-specific intercellular adhesion molecule-3 grabbing nonintegrin; gp120 : glycoprotein 120; PMA : phorbol 12-myristate 13-acetate; MEK1/2 : mitogen-activated protein kinase/extracellular signal-regulated kinase; PBMCs : peripheral blood mononuclear cells; PCR : polymerase chain reaction; CCR5 : CC-chemokine receptor-5; dNTP : deoxyribonucleotide triphosphate; RPMI : Royal Park Memorial Institute; pRL-TK : promoter-Renilla luciferase reporter plasmid; ERK : extracellular signal-regulated kinase; JAK : Janus activated kinase; STAT : signal transducers and activators of transcription; Lyf-1 : lymphocyte transcription factor 1; Sp-1 : specificity protein 1; TLR8 : toll-like receptor 8; IL-1β : interleukin 1–beta; IL-6 : interleukin 6; TNF-α : tumor necrosis factor–alpha; IL-4 : interleukin 4