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Background: RC-101 is a congener of the antiretroviral peptide retrocyclin, which we and others have reported is active against clinical HIV-1 isolates from all major clades, does not hemagglutinate, and is non-toxic and non-inflammatory in cervicovaginal cell culture. Herein, film-formulated RC-101 was assessed for its antiviral activity in vitro, safety in vivo, retention in the cervix and vagina, and ability to remain active against HIV-1 and SHIV after intravaginal application in macaques., Methodology/principal Findings: RC-101 was formulated as a quick-dissolving film (2000 µg/film), retained complete activity in vitro as compared to unformulated peptide, and was applied intravaginally in six pigtailed macaques daily for four days. At one and four days following the final application, the presence of RC-101 was assessed in peripheral blood, cervicovaginal lavage, cytobrushed cervicovaginal cells, and biopsied cervical and vaginal tissues by quantitative western blots. One day following the last film application, cervical biopsies from RC-101-exposed and placebo-controlled macaques were collected and were subjected to challenge with RT-SHIV in an ex vivo organ culture model. RC-101 peptide was detected primarily in the cytobrush and biopsied cervical and vaginal tissues, with little to no peptide detected in lavage samples, suggesting that the peptide was associated with the cervicovaginal epithelia. RC-101 remained in the tissues and cytobrush samples up to four days post-application, yet was not detected in any sera or plasma samples. RC-101, extracted from cytobrushes obtained one day post-application, remained active against HIV-1 BaL. Importantly, cervical biopsies from RC-101-treated animals reduced RT-SHIV replication in ex vivo organ culture as compared to placebo-treated animals., Conclusions/significance: Formulated RC-101 was stable in vivo and was retained in the mucosa. The presence of antivirally active RC-101 after five days in vivo suggests that RC-101 would be an important molecule to develop further as a topical microbicide to prevent HIV-1 transmission.

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.

Axonal damage represented by accumulation of beta-amyloid precursor protein (beta-APP) develops in numerous central nervous system (CNS) diseases including human immunodeficiency virus (HIV) infection. To study the underlying mechanisms of axonal damage associated with HIV CNS infection, the amount of axonal beta-APP immunostaining in the corpus callosum of 24 simian immunodeficiency virus (SIV)-infected macaques and 3 control macaques was measured by computerized image analysis. The amounts of beta-APP accumulation were then compared with time post-inoculation, extent and character of CNS inflammation, and viral load in the CNS measured by the amount of immunohistochemical staining for the viral transmembrane protein gp41. Significant increases over control values were present in 10 of 24 SIV-infected animals. SIV encephalitis was present in 9 of the 10 animals with elevated beta-APP Increases in beta-APP correlated most strongly with levels of SIV gp41 in the brain (p = 0.005), but significant associations with macrophage infiltration and microglial activation (p = 0.04) and infiltration by cytotoxic lymphocytes (p = 0.05) also were identified. These data demonstrate that beta-APP accumulation in the white matter of SIV-infected macaques develops during SIV infection in close correlation with levels of viral replication and may serve as a sensitive marker of neuronal/axonal damage mediated by viral proteins.

Macrophage chemoattractant protein-1 (MCP-1) may be a key trigger for the influx of macrophages into the brain in human immunodeficiency virus (HIV) encephalitis. In this study, simian immunodeficiency virus-infected macaques that developed moderate-to-severe encephalitis had significantly higher MCP-1 levels in cerebrospinal fluid (CSF) than in plasma as early as 28 days after inoculation, which was before the development of brain lesions. In contrast, CSF:plasma MCP-1 ratios remained constant at preinoculation levels in macaques that developed minimal or no encephalitis. Abundant MCP-1 protein and mRNA were detected in both macrophages and astrocytes in the brain. Macaques with increased MCP-1 in CSF had significantly greater expression of markers of macrophage and microglia activation and infiltration (CD68; P= .003) and astrocyte activation (glial fibrillary acidic protein; P= .019 and P= .031 in white and gray matter, respectively). The results suggest that the CSF:plasma MCP-1 ratio may be a valuable prognostic marker for the development of HIV-induced central nervous system disease.

Lymphocytic interstitial pneumonia of HIV-infected individuals and SIV pneumonia of macaques are both characterized by diffuse infiltration of the lungs with lymphocytes, plasma cells, and macrophages. This study was undertaken to determine whether there are specific, macrophage-tropic genotypes that selectively replicate in the lung of macaques with SIV pneumonia, as in SIV encephalitis. Using a rapid, reproducible SIV/macaque model of AIDS, 11 pig-tailed macaques were intravenously inoculated with an immunosuppressive viral strain, SIV/DeltaB670, and a macrophage-tropic molecule clone, SIV/17E-Fr, and euthanized at 3 months postinoculation. All 11 macaques had severe (6 macaques) or moderate (5 macaques) pneumonia. To identify the viral genotypes that were replicating in the lung parenchyma, bronchoalveolar lavage (BAL) cells, and peripheral blood mononuclear cells (PBMC) of each macaque, RNA was isolated and the SIV env V1 region was amplified, cloned, and sequenced. Lung homogenates and BAL cells contained a more limited repertoire of viral genotypes than PBMC. SIV/17E-Fr was the major genotype in the lungs of 5 macaques and in BAL cells of 6 macaques. The remainder of the macaques had SIV/17E-Fr and the macrophage-tropic strains of SIV/DeltaB670 clones 2 and 12. In contrast, SIV/17E-Fr was the predominant strain in the PBMC of only 3 of 11 macaques. The viral strain that predominated in PBMC was rarely the strain that predominated in the lungs (only 3 of 11 macaques). The severity of pulmonary lesions did not correlate with the levels of viral RNA in lung homogenates or in plasma. However, when only SIV/17E-Fr was expressed in the lung, the viral load in the lung was significantly higher (P = 0.016) than when SIV/DeltaB670 was present alone or in combination with SIV/17E-Fr. These data suggest that SIV pneumonia is associated with selective replication of specific macrophage-tropic genotypes in the lung and that SIV/17E-Fr has a selective advantage for replication in the lung., (Copyright 2001 Academic Press.)