Longitudinal analysis of simian immunodeficiency virus (SIV) replication in the lungs: compartmentalized regulation of SIV.

BACKGROUND: Before the onset of AIDS, replication of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) in the lungs is considered to be latent. When and how virus replication is controlled in the lungs is unclear. In the present study, we examine virus replication in the lungs and in cells recovered from bronchoalveolar lavage (BAL) samples in a comprehensive, longitudinal analysis of an SIV/macaque model. METHODS: Gene-specific RNA and DNA were quantitated by polymerase chain reaction (PCR) and by real-time reverse-transcription PCR (RT-PCR). Alveolar macrophages were isolated using Dynabeads CD14 (Invitrogen). Expression of CCAAT/enhancer-binding protein beta (C/EBP beta ) isoforms was examined by Western blot analysis. RESULTS: SIV replication occurred in the lungs during acute infection and correlated with plasma viral load. Innate immune responses involving interferon- beta and the dominant-negative isoform of C/EBP beta were induced at this time. SIV RNA expression was suppressed in the lungs during asymptomatic infection, when no correlation existed with plasma viral load until SIV RNA levels rebounded again during late-stage disease. Modulation of viral RNA levels in BAL cells reflected RNA levels in lung tissue throughout each phase of infection. CONCLUSION: Quantitation of SIV RNA in BAL cells provides a consistent surrogate assessment of virus replication in lung tissue. Innate immune responses contribute to compartmentalized suppression of acute SIV replication in the lungs.

Mechanism for the establishment of transcriptional HIV latency in the brain in a simian immunodeficiency virus-macaque model.

BACKGROUND: The brain is considered to be a reservoir of latent human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV). We examined the mechanism by which innate immune responses contribute to the establishment of this reservoir. METHODS: Gene-specific RNA and DNA were quantitated using real-time reverse-transcription polymerase chain reaction (RT-PCR). Protein expression was examined using Western blot analysis. Binding to and regulation of the SIV long terminal repeat (LTR) was examined using electrophoretic mobility shift assay, luciferase reporter constructs, and chromatin immunoprecipitation assay. RESULTS: Interferon-beta (IFN-beta) and myxovirus A (MxA) mRNA are produced in the brain during acute SIV infection. IFN-beta both suppresses SIV LTR activity and induces expression of the dominant-negative isoform of CCAAT/enhancer-binding protein-beta (C/EBP-beta). C/EBP-beta and its dominant-negative isoform respectively enhance and suppress histone acetylation at the SIV LTR and are present at the SIV LTR in vivo. SIV DNA persists when viral RNA is undetectable in the brain, and activation of the LTR is suppressed at the level of histone acetylation. CONCLUSION: Innate immune responses to virus infection that suppress acute virus replication in the brain also facilitate transcriptional latency of SIV. These data provide the first mechanistic model of HIV latency in the brain.

Neuroprotective and anti-human immunodeficiency virus activity of minocycline.

CONTEXT: The prevalence of human immunodeficiency virus (HIV) central nervous system (CNS) disease has not decreased despite highly active antiretroviral therapy. Current antiretroviral drugs are expensive, have significant adverse effects including neurotoxicity, and few cross the blood-brain barrier. OBJECTIVE: To examine the ability of minocycline, an antibiotic with potent anti-inflammatory and neuroprotective properties, to protect against encephalitis and neurodegeneration using a rapid, high viral load simian immunodeficiency virus (SIV) model of HIV-associated CNS disease that constitutes a rigorous in vivo test for potential therapeutics. DESIGN AND SUBJECTS: Five SIV-infected pigtailed macaques were treated with 4 mg/kg per day of minocycline beginning at early asymptomatic infection (21 days after inoculation). Another 6 macaques were inoculated with SIV but remained untreated. Blood and cerebrospinal fluid (CSF) samples were taken on days 7, 10, 14, 21, 28, 35, 43, 56, 70, 77, and 84, and all macaques were humanely killed at 84 days after inoculation, a time that corresponds to late-stage infection in HIV-infected individuals. MAIN OUTCOME MEASURES: Blood and CSF samples were tested for viral load by real-time reverse transcription-polymerase chain reaction and levels of monocyte chemoattractant protein 1 were quantitated by enzyme-linked immunosorbent assay. The presence and severity of encephalitis was determined by microscopic examination of tissues. Central nervous system inflammation was further assessed by measuring infiltration and activation of macrophages, activation of p38 mitogen-activated protein kinase and expression of amyloid precursor protein by quantitative immunohistochemistry. RESULTS: Minocycline-treated macaques had less severe encephalitis (P = .02), reduced CNS expression of neuroinflammatory markers (major histocompatibility complex class II, P = .03; macrophage marker CD68 , P = .07; T-cell intracytoplasmic antigen 1, P = .03; CSF monocyte chemoattractant protein 1, P = .001), reduced activation of p38 mitogen-activated protein kinase (P<.001), less axonal degeneration (beta-amyloid precursor protein, P = .03), and lower CNS virus replication (viral RNA, P = .04; viral antigen, P = .04). In in vitro analysis, minocycline suppression of HIV and SIV replication in cultured primary macrophages did not correlate with suppression of activation of p38-mitogen-activated protein kinase pathways, whereas suppression in primary lymphocytes correlated with suppression of p38 activation. CONCLUSIONS: In this experimental SIV model of HIV CNS disease, minocycline reduced the severity of encephalitis, suppressed viral load in the brain, and decreased the expression of CNS inflammatory markers. In vitro, minocycline inhibited SIV and HIV replication. These findings suggest that minocycline, a safe, inexpensive, and readily available antibiotic should be investigated as an anti-HIV therapeutic.

The coxsackievirus and adenovirus receptor interacts with the multi-PDZ domain protein-1 (MUPP-1) within the tight junction.

The coxsackievirus and adenovirus receptor (CAR) is a component of the epithelial cell tight junction. In a yeast two-hybrid screen we identified the multi-PDZ domain protein MUPP1 as an interaction partner for the CAR cytoplasmic domain. CAR and MUPP1 were found to colocalize at the tight junction, to coprecipitate from epithelial cells, and to interact in vitro. The interaction was found to specifically involve the PDZ-binding motif within the CAR C terminus and MUPP1 PDZ domain 13. In transfected cells, CAR recruited MUPP1 to cell-cell contacts. The inhibition of CAR expression with small interfering RNA inhibited MUPP1 localization to the tight junction. The results indicated that CAR interacts with MUPP1 and is involved in MUPP1 recruitment to the tight junction.