No evidence of ongoing HIV replication or compartmentalization in tissues during combination antiretroviral therapy: Implications for HIV eradication.

HIV persistence during combination antiretroviral therapy (cART) is the principal obstacle to cure. Mechanisms responsible for persistence remain uncertain; infections may be maintained by persistence and clonal expansion of infected cells or by ongoing replication in anatomic locations with poor antiretroviral penetration. These mechanisms require different strategies for eradication, and determining their contributions to HIV persistence is essential. We used phylogenetic approaches to investigate, at the DNA level, HIV populations in blood, lymphoid, and other infected tissues obtained at colonoscopy or autopsy in individuals who were on cART for 8 to 16 years. We found no evidence of ongoing replication or compartmentalization of HIV; we did detect clonal expansion of infected cells that were present before cART. Long-term persistence, and not ongoing replication, is primarily responsible for maintaining HIV. HIV-infected cells present when cART is initiated represent the only identifiable source of persistence and is the appropriate focus for eradication.

Independent lung ventilation in the postoperative management of single lung transplantation: case report.

Independent lung ventilation (ILV) is a ventilation strategy used in patients with significant differences in respiratory mechanics between the 2 lungs owing to asymmetric or unilateral lung diseases. We report the case of a 66-year-old patient treated with ILV for a primary graft dysfunction occurred early after single lung transplantation. On intensive care unit admission, the patient was ventilated with pressure-controlled mechanical ventilation. Despite efforts to optimize ventilation and medical therapy, his clinical condition progressively worsened, manifesting hypoxemia, hypercapnia, and radiologic evidence of hyperinflation of the native lung, collapse of the graft, and mediastinal shift. The ventilation was therefore switched to ILV. A constant improvement in clinical conditions, arterial blood gas parameters, and radiologic findings was then obtained. The patients was weaned from mechanical ventilation and finally successfully extubated.

Adaptive support ventilation versus synchronized intermittent mandatory ventilation with pressure support in weaning patients after orthotopic liver transplantation.

BACKGROUND: The extubation phase is an extremely critical moment in patients who have undergone orthotopic liver transplantation, who do not always have the advantage of long-lasting positive-pressure ventilation and positive expiratory end pressure; these factors can lead to splanchnic venous congestion, and this is why a rapid extubation can represent a great benefit for the graft. METHODS: The aim of this study was to compare the adaptive support ventilation (ASV) mode with the standard mode of weaning in our intensive care unit, synchronized intermittent mandatory ventilation with pressure support (P-SIMV), in patients who received orthotopic liver transplantation. ASV is a positive-pressure mode, in which pressure level and respiratory rate are automatically adjusted according to measured lung dynamics at each breath. Eligible patients were assigned to either ASV or P-SIMV group. The weaning protocol was based on the individual respiratory activity and structured in 4 different phases. RESULTS: The average length of intubation was significantly shorter in the ASV group than in the P-SIMV group (90±13 vs 153±22 minutes, P=.05). The total modifications to the ventilator settings were significantly larger in the P-SIMV group (1.5±1 vs 6±2; P=.003). CONCLUSIONS: Our results suggest that although both procedures are safe and easy to apply, ASV is superior in terms of weaning times, and it simplifies respiratory management. The better patient-machine interaction in ASV has been highlighted by other authors for different clusters of patients.

HIV latency. Specific HIV integration sites are linked to clonal expansion and persistence of infected cells.

The persistence of HIV-infected cells in individuals on suppressive combination antiretroviral therapy (cART) presents a major barrier for curing HIV infections. HIV integrates its DNA into many sites in the host genome; we identified 2410 integration sites in peripheral blood lymphocytes of five infected individuals on cART. About 40% of the integrations were in clonally expanded cells. Approximately 50% of the infected cells in one patient were from a single clone, and some clones persisted for many years. There were multiple independent integrations in several genes, including MKL2 and BACH2; many of these integrations were in clonally expanded cells. Our findings show that HIV integration sites can play a critical role in expansion and persistence of HIV-infected cells.

HIV diagnosis and testing: what every healthcare professional can do (and why they should).

Over the last thirty years, the human immunodeficiency virus (HIV) epidemic has matured. In the United States, HIV has changed from an explosive outbreak to an endemic disease; currently, an estimated 1.1 million people are infected with HIV, including a substantial number who are unaware of their status. With recent findings demonstrating the high transmissibility of HIV early in infection, and the potential benefit of early initiation of treatment, it is essential to identify as many infected individuals as possible. The Centers for Disease Control and Prevention (CDC) has expanded HIV testing to include any healthcare setting, including dental offices. Testing advances, including oral testing, have reduced the window period of HIV infection. Dental care represents a key, reliable, independent, and confidential link between the healthcare system and the general population that has been under-utilized in the effort to control the HIV epidemic. HIV testing is straightforward, and knowledge of the types of testing will afford dentists an important opportunity to help advance and preserve the health of their patients and to promote the public health of their community. Here, we review the basics of HIV testing and discuss new changes in the approach to HIV diagnostics.

Nucleic Acid, Antibody, and Virus Culture Methods to Detect Xenotropic MLV-Related Virus in Human Blood Samples.

The MLV-related retrovirus, XMRV, was recently identified and reported to be associated with both prostate cancer and chronic fatigue syndrome. At the National Cancer Institute-Frederick, MD (NCI-Frederick), we developed highly sensitive methods to detect XMRV nucleic acids, antibodies, and replication competent virus. Analysis of XMRV-spiked samples and/or specimens from two pigtail macaques experimentally inoculated with 22Rv1 cell-derived XMRV confirmed the ability of the assays used to detect XMRV RNA and DNA, and culture isolatable virus when present, along with XMRV reactive antibody responses. Using these assays, we did not detect evidence of XMRV in blood samples (N = 134) or prostate specimens (N = 19) from two independent cohorts of patients with prostate cancer. Previous studies detected XMRV in prostate tissues. In the present study, we primarily investigated the levels of XMRV in blood plasma samples collected from patients with prostate cancer. These results demonstrate that while XMRV-related assays developed at the NCI-Frederick can readily measure XMRV nucleic acids, antibodies, and replication competent virus, no evidence of XMRV was found in the blood of patients with prostate cancer.

Short-course raltegravir intensification does not reduce persistent low-level viremia in patients with HIV-1 suppression during receipt of combination antiretroviral therapy.

BACKGROUND: Combination antiretroviral therapy suppresses but does not eradicate human immunodeficiency virus type 1 (HIV-1) in infected persons, and low-level viremia can be detected despite years of suppressive antiretroviral therapy. Short-course (28-day) intensification of standard antiretroviral combination therapy is a useful approach to determine whether complete rounds of HIV-1 replication in rapidly cycling cells contribute to persistent viremia. We investigated whether intensification with the integrase inhibitor raltegravir decreases plasma HIV-1 RNA levels in patients receiving suppressive antiretroviral therapy. METHODS: Subjects (n = 10) with long-term HIV-1 suppression receiving combination antiretroviral regimens had their regimens intensified for 4 weeks with raltegravir. Plasma HIV-1 RNA level was determined before, during, and after the 4-week intensification period, using a sensitive assay (limit of detection, 0.2 copies of HIV-1 RNA/mL of plasma). A 4-week intensification course was chosen to investigate potential HIV-1 replication in cells with relatively short (approximately 1-14-day) half-lives. RESULTS: There was no evidence in any subject of a decline in HIV-1 RNA level during the period of raltegravir intensification or of rebound after discontinuation. Median levels of HIV-1 RNA before (0.17 log10 copies/mL), during (0.04 log10 copies/mL), and after (0.04 log10 copies/mL) raltegravir intensification were not significantly different (P > .1 for all comparisons in parametric analyses). High-performance liquid chromatography and mass spectroscopy experiments confirmed that therapeutic levels of raltegravir were achieved in plasma during intensification. CONCLUSIONS: Intensification of antiretroviral therapy with a potent HIV-1 integrase inhibitor did not decrease persistent viremia in subjects receiving suppressive regimens, indicating that rapidly cycling cells infected with HIV-1 were not present. Eradication of HIV-1 from infected persons will require new therapeutic approaches. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00618371.

Treatment intensification does not reduce residual HIV-1 viremia in patients on highly active antiretroviral therapy.

In HIV-1-infected individuals on currently recommended antiretroviral therapy (ART), viremia is reduced to <50 copies of HIV-1 RNA per milliliter, but low-level residual viremia appears to persist over the lifetimes of most infected individuals. There is controversy over whether the residual viremia results from ongoing cycles of viral replication. To address this question, we conducted 2 prospective studies to assess the effect of ART intensification with an additional potent drug on residual viremia in 9 HIV-1-infected individuals on successful ART. By using an HIV-1 RNA assay with single-copy sensitivity, we found that levels of viremia were not reduced by ART intensification with any of 3 different antiretroviral drugs (efavirenz, lopinavir/ritonavir, or atazanavir/ritonavir). The lack of response was not associated with the presence of drug-resistant virus or suboptimal drug concentrations. Our results suggest that residual viremia is not the product of ongoing, complete cycles of viral replication, but rather of virus output from stable reservoirs of infection.

Human immunodeficiency virus type 1 population genetics and adaptation in newly infected individuals.

Studies on human immunodeficiency virus type 1 (HIV-1) diversity are critical for understanding viral pathogenesis and the emergence of immune escape variants and for design of vaccine strategies. To investigate HIV-1 population genetics, we used single-genome sequencing to obtain pro-pol and env sequences from longitudinal samples (n = 93) from 14 acutely or recently infected patients. The first available sample after infection for 12/14 patients revealed HIV-1 populations with low genetic diversity, consistent with transmission or outgrowth of a single variant. In contrast, two patients showed high diversity and coexistence of distinct virus populations in samples collected days after a nonreactive enzyme-linked immunosorbent assay or indeterminate Western blot, consistent with transmission or outgrowth of multiple variants. Comparison of PR and RT sequences from the first sample for all patients with the consensus subgroup B sequence revealed that nearly all nonsynonymous differences were confined to identified cytotoxic T-lymphocyte (CTL) epitopes. For HLA-typed patients, mutations compared to the consensus in transmitted variants were found in epitopes that would not be recognized by the patient's major histocompatibility complex type. Reversion of transmitted mutations was rarely seen over the study interval (up to 5 years). These data indicate that acute subtype B HIV-1 infection usually results from transmission or outgrowth of single viral variants carrying mutations in CTL epitopes that were selected prior to transmission either in the donor or in a previous donor and that reversion of these mutations can be very slow. These results have important implications for vaccine strategies because they imply that some HLA alleles could be compromised in newly acquired HIV infections.

Persistence of nevirapine-resistant HIV-1 in women after single-dose nevirapine therapy for prevention of maternal-to-fetal HIV-1 transmission.

Single-dose nevirapine (sdNVP) for prevention of mother-to-child transmission of HIV-1 can select nevirapine (NVP)-resistant variants, but the frequency, duration, and clinical significance of this resistance is not well defined. We used a sensitive allele-specific PCR assay to assess the emergence and persistence of NVP-resistant variants in plasma samples from 22 women with HIV-1 subtype C infection who participated in a study of sdNVP for prevention of mother-to-child transmission of HIV-1. The women were categorized into three groups on the basis of detection of NVP resistance by standard genotype analysis. Group 1 (n = 6) had NVP resistance detected at 2 and 6 mo after sdNVP, but not at 12 mo. Group 2 (n = 9) had NVP resistance detected at 2 mo, but not 6 mo. Group 3 (n = 7) had no NVP resistance detected at any time point. Allele-specific PCR analysis for the two most common NVP resistance mutations (K103N and Y181C) detected NVP-resistant variants in most (16 of 21) samples that were negative for NVP resistance by standard genotype, at levels ranging from 0.1% to 20% 1 yr after treatment. The frequency of NVP-resistant mutations decreased over time, but persisted above predose levels for more than 1 yr in > or = 23% of the women. These findings highlight the urgent need for studies assessing the impact of sdNVP on the efficacy of subsequent antiretroviral therapy containing NVP or other nonnucleoside reverse transcriptase inhibitors.

A robust measure of HIV-1 population turnover within chronically infected individuals.

A simple nonparameteric test for population structure was applied to temporally spaced samples of HIV-1 sequences from the gag-pol region within two chronically infected individuals. The results show that temporal structure can be detected for samples separated by about 22 months or more. The performance of the method, which was originally proposed to detect geographic structure, was tested for temporally spaced samples using neutral coalescent simulations. Simulations showed that the method is robust to variation in samples sizes and mutation rates, to the presence/absence of recombination, and that the power to detect temporal structure is high. By comparing levels of temporal structure in simulations to the levels observed in real data, we estimate the effective intra-individual population size of HIV-1 to be between 10(3) and 10(4) viruses, which is in agreement with some previous estimates. Using this estimate and a simple measure of sequence diversity, we estimate an effective neutral mutation rate of about 5 x 10(-6) per site per generation in the gag-pol region. The definition and interpretation of estimates of such "effective" population parameters are discussed.

Effect of rev on the cytoplasmic localization of intron-containing human immunodeficiency virus type 1 RNA.

Human immunodeficiency virus type 1 (HIV-1) proteins are expressed from both intron-containing and completely spliced RNAs. Rev, an HIV-1 regulatory protein, is necessary for the expression of intron-containing RNAs. The effect of Rev on the subcellular localization of intron-containing HIV-1 RNA was examined by in situ RNA hybridization. In the presence of Rev, intron-containing HIV-1 RNA accumulated at the nuclear membrane and within the cytoplasm of transfected cells. In the absence of Rev, intron-containing HIV-1 RNA accumulated within the nucleus. In approximately 20% of the cells transfected in the absence of Rev, intron-containing HIV-1 RNA was also found in the cytoplasm. Differences in the subcytoplasmic localization of intron-containing HIV-1 RNA in the presence and absence of Rev were not observed using in situ RNA hybridization. To determine the effect of Rev on RNA localization within the cytoplasm, an extensive fractionation protocol involving both hypotonic and detergent lysis was used. In the presence of Rev, 40.9 +/- 4.6% of the cytoplasmic intron-containing HIV-1 RNA was released by hypotonic lysis. A similar fractionation profile was seen for several other translated viral and cellular RNAs. However, in the absence of Rev, only 16.5 +/- 5.1% of the cytoplasmic intron-containing HIV-1 RNA was released on hypotonic lysis (P < 0. 005). Thus the cytoplasmic fractionation pattern of this RNA was altered in the absence of Rev.

The expression of the essential nuclear splicing factor SC35 is altered by human immunodeficiency virus infection.

In order to identify cellular genes differentially expressed during human immunodeficiency virus 1 (HIV-1) infection, we conducted a screen using differential display. The sequence of one of the clones, 0085, was identical to a sequence present in the RNA splicing factor SC35. Since splicing is an essential point of control during HIV gene expression, we carried out additional experiments to examine SC35 expression during HIV infection. RNA blots confirmed that SC35 RNA was induced following HIV infection; a 2-3-fold increase in expression of SC35 RNA was detected by day 2 of HIV infection. Fluorescence-activated cell-sorting revealed concomitant increases in SC35 protein and double staining studies demonstrated that increases in SC35 protein occurred specifically in the HIV-infected cells. Laser scanning confocal microscopy revealed SC35 was associated with 2 microm 'nuclear speckles' in both infected and uninfected cells, suggesting that increases in SC35 accumulated in these nuclear structures and that HIV infection did not alter the intracellular distribution of SC35. These findings indicate that an essential splicing factor is induced after HIV infection, suggesting that the consequences of HIV infection include alterations in relative levels of a splicing factor.

Human T-cell leukemia virus type 1 Tax and cell cycle progression: role of cyclin D-cdk and p110Rb.

Human T-cell leukemia virus type 1 is etiologically linked to the development of adult T-cell leukemia and various human neuropathies. The Tax protein of human T-cell leukemia virus type I has been implicated in cellular transformation. Like other oncoproteins, such as Myc, Jun, and Fos, Tax is a transcriptional activator. How it mechanistically dysregulates the cell cycle is unclear. Previously, it was suggested that Tax affects cell-phase transition by forming a direct protein-protein complex with p16(INK4a), thereby inactivating an inhibitor of G1-to-S-phase progression. Here we show that, in T cells deleted for p16(INK4a), Tax can compel an egress of cells from G0/G1 into S despite the absence of serum. We also show that in undifferentiated myocytes, expression of Tax represses cellular differentiation. In both settings, Tax expression was found to increase cyclin D-cdk activity and to enhance pRb phosphorylation. In T cells, a Tax-associated increase in steady-state E2F2 protein was also documented. In searching for a molecular explanation for these observations, we found that Tax forms a protein-protein complex with cyclin D3, whereas a point-mutated and transcriptionally inert Tax mutant failed to form such a complex. Interestingly, expression of wild-type Tax protein in cells was also correlated with the induction of a novel hyperphosphorylated cyclin D3 protein. Taken together, these findings suggest that Tax might directly influence cyclin D-cdk activity and function, perhaps by a route independent of cdk inhibitors such as p16(INK4a).

Efficient expression by an alphavirus replicon of a functional ribozyme targeted to human immunodeficiency virus type 1.

Intracellular applications of ribozymes have been limited partly by the availability of suitable high-expression systems. For RNA effectors, consideration of an RNA virus vector system for delivery and expression is reasonable. We show that alphavirus replicons can be highly efficient nonintegrating ribozyme-expressing vectors. Using a hammerhead ribozyme targeted to a highly conserved sequence in the U5 region of the human immunodeficiency virus type 1 (HIV-1) long terminal repeat, we demonstrate that a full-length 8.3-kb Semliki Forest virus ribozyme (SFVRz) chimeric RNA maintains catalytic activity. SFVRz is packaged into viral particles, and these particles transduce mammalian cells efficiently. SFVRz-transduced BHK cells were found to produce large amounts of genomic and subgenomic forms of ribozyme-containing RNAs that are functional in cleaving a U5-tagged mRNA. The RNase protection assay shows that HIV-1 U5-chloramphenicol acetyltransferase mRNA expressed intracellularly from an RNA polymerase II promoter is quantitatively eliminated in SFVRz-transduced BHK cells.

Selenium supplementation suppresses tumor necrosis factor alpha-induced human immunodeficiency virus type 1 replication in vitro.

Selenium is a nutritionally essential trace element that is important for optimal function of the immune system. It is incorporated into selenoproteins as the amino acid selenocysteine and it is known to inhibit the expression of some viruses. In this study, we show that selenium supplementation for 3 days prior to exposure to tumor necrosis factor alpha (TNF-alpha) partially suppresses the induction of human immunodeficiency virus type 1 (HIV-1) replication in both chronically infected T lymphocytic and monocytic cell lines. In acute HIV-1 infection of T lymphocytes and monocytes in the absence of exogenous TNF-alpha, the suppressive effect of selenium supplementation was not observed. However, selenium supplementation did suppress the enhancing effect of TNF-alpha on HIV-1 replication in vitro in acutely infected human monocytes, but not in T lymphocytes. Selenium supplementation also increased the activities of the selenoproteins, glutathione peroxidase (GPx) and thioredoxin reductase (TR), which serve as cellular antioxidants. Taken together, these results suggest that selenium supplementation may prove beneficial as an adjuvant therapy for AIDS through reinforcement of endogenous antioxidative systems.

Infection and pathogenicity of chimeric simian-human immunodeficiency viruses in macaques: determinants of high virus loads and CD4 cell killing.

Chimeric simian-human immunodeficiency viruses (SHIVs) carrying envelope glycoproteins derived from a T cell-macrophage dual-tropic primary isolate (human immunodeficiency virus type 1 [HIV-1] strain DH12) were constructed. When inoculated into macaque monkeys, SHIV(MD14) carrying simian immunodeficiency virus-derived nef established significantly higher virus loads than did SHIV(MD1), which contains the HIV-1 nef gene. Three patterns of CD4 cell depletion were observed in infected monkeys: exponential and irreversible loss to undetectable levels within 10 weeks of infection; marked reduction during acute infection followed by partial recovery and stabilization (lasting from 10 weeks to > 1 year), with a later decline to undetectable levels in some animals; and a transient loss during acute infection. The induced immunodeficiency was accompanied by CD4 cell counts of < 50 cells/microL and was associated with Pneumocystis carinii pneumonia, cytomegalovirus meningoencephalitis, lymphoid depletion, and thymic atrophy.

Bimodal down-regulation of CD4 in cells expressing human immunodeficiency virus type 1 Vpu and Env.

We analysed clones of HeLa cells stably expressing the human immunodeficiency virus (HIV-1) envelope gene (env) and the HIV-1 receptor, CD4. Surprisingly, individual clones were found to consist of two distinct populations of cells differing by about 10-fold in the level of surface CD4. When high and low CD4-expressing cells were separated by FACS, each subpopulation gave rise to a mixture of high and low CD4-expressing cells after several days in culture. High and low CD4-expressing subpopulations did not differ with respect to the amount of intracellular Env, but there was an inverse correlation between CD4 and another HIV-1 protein encoded by the same segment of the HIV genome, Vpu. High surface CD4 cells had high levels of intracellular CD4, largely in the perinuclear region, and low levels of Vpu with a diffuse staining pattern. Conversely, low surface CD4 cells had low levels of intracellular CD4 with a diffuse staining pattern, and high levels of Vpu, largely in the perinuclear region. Vectors containing mutant versions of either Env or Vpu failed to down-regulate surface CD4. The phenomenon of bimodal expression of a surface protein in cells derived from single clones provides a simple model of differentiation in vitro. We show how a hypothetical interaction between CD4 and a multimer of Vpu, the multimerization of which is cooperative, would lead to bimodal expression of CD4. This model may be generalized and could explain other cellular 'switches'.

Human immunodeficiency virus type 1 infection of H9 cells induces increased glucose transporter expression.

A clone obtained from a differential display screen for cellular genes with altered expression during human immunodeficiency virus (HIV) infection matched the sequence for the human GLUT3 facilitative glucose transporter, a high-velocity-high-affinity facilitative transporter commonly expressed in neurons of the central nervous system. Northern (RNA) analysis showed that GLUT3 expression increased during infection. Flow cytometry showed that GLUT3 protein expression increased specifically in the HIV-infected cells; this increase correlated with increased 2-deoxyglucose transport in the HIV-infected culture. HIV infection therefore leads to increased expression of a glucose transporter normally expressed at high levels in other cell types and a corresponding increase in glucose transport activity. If HIV infection places increased metabolic demands on the host cell, changes in the expression of a cellular gene that plays an important role in cellular metabolism might provide a more favorable environment for viral replication.