ISSN:0269-9370    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

ObjectiveAnalysis of the T cell receptor Vβ repertoire during HIV infection reveals expansions in multiple Vβ families of CD8 T cells, but their antigenic specificity is ill-defined. We sought to determine the TCR Vβ repertoire of HIV specific CD8 T lymphocytes in infected children.Design/methodsWe performed flow cytometry to examine TCR Vβ families as identified by specific monoclonal antibodies and binding of HIV peptide loaded tetrameric MHC complexes in peripheral blood samples from a group of HIV infected children.ResultsSimultaneous assessment of 12 selected expanded Vβ families amongst nine HIV infected patients for tetramer binding revealed only one child in whom the expanded Vβ population bound HIV Gag or Pol tetramers. In four HIV infected children, percentage tetramer binding cells was determined in 21 TCR Vβ families. The tetramer binding cells of three children exhibited a widely distributed TCR Vβ repertoire while in the fourth patient they were preferentially localized within two TCR Vβ families. Repeat analysis revealed that the TCR Vβ repertoire of tetramer binding cells was stable.ConclusionsThese data provide evidence that the HIV-specific CD8 T cell response in children is usually distributed widely among many different TCR Vβ families. The heterogeneity of the TCR Vβ repertoire usage by the antigen specific CD8 T cells may reflect the dynamic interaction between host and pathogen during the course of HIV infection and may be influenced by the rate of viral mutation, CD4 T cell helper activity, or other factors.

ISSN:0269-9370    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

DesignHIV Env interaction with the corresponding chemokine receptor dictates the molecular mechanism of death of both HIV-infected and uninfected primary CD4 T cells. CXCR4/T tropic HIV virus (X4) triggers CD4 T cell death through a caspase independent mechanism,whereas CCR5/M tropic HIV virus (R5) HIV triggers a caspase dependent death. In the present study, we have investigated the pathway whereby R5 Env–CR5 interactions lead to a caspase dependent cell death.MethodsCD4 T cells were infected with X4 or R5 HIV strains, or were mock infected. After infection, cells were treated with caspase inhibitors or decoys of death receptor signaling pathways and cell viability was analyzed. The role of R5 HIV Env in induction of cell death of uninfected T cells was analyzed by co-culturing uninfected CD4 T cells with R5 Env expressing cells in the absence or presence of various inhibitors of death receptor signaling.ResultsInfection of CD4 T cells with R5, but not with X4 HIV strains results in the activation of caspase-8 and cell death that is reversed by a decoy of the Fas receptor. Isolated activation of CCR5 by membrane-bound, or soluble R5 Env causes a Fas- and caspase-8 dependent death also of uninfected CD4 T cells. Additional studies demonstrate that isolated CCR5 activation by R5 Env leads to bothde novoexpression of FasL and induction of susceptibility to Fas-mediated apoptosis in resting primary CD4 T cells.ConclusionsThese results ascribe to CCR5 a novel role in activating the Fas pathway and caspase-8 as well as triggering FasL production when activated by R5 Env, ultimately causing CD4 T cell death.

ISSN:0269-9370    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

BackgroundThe effect of interleukin-2 (IL-2) in combination with antiretroviral therapy on HIV-1 replication and reservoirs was investigated.MethodsIn a prospective, open-label trial, 56 asymptomatic HIV-1-infected subjects (CD4 T cell count > 350 × 106cells/l) were randomized to highly active antiretroviral therapy (HAART: stavudine, lamivudine, nelfinavir, saquinavir) with or without IL-2 (9 megaunits daily for 5 days in 6-weekly intervals for a total of eight cycles). Productive and latent infection were analysed in peripheral blood, and residual virus replication in the lymphoid tissue and in the cerebrospinal fluid. The influence of IL-2 on viral rebound after treatment discontinuation was studied.ResultsVirus replication was detected in 21 of 31 on-treatment lymph nodes despite undetectable plasma viraemia. Viral RNA was found in resting as well as in proliferating cells. RNA-negative patients tended towards more rapid proviral DNA elimination. Supplementary IL-2 led to a greater increase in CD4 T cell counts than HAART alone (P< 0.001), resulting in normalization in ~90% of IL-2-treated patients compared with ~50% HAART-only subjects. IL-2 had no beneficial effect on virus replication and on proviral DNA in peripheral blood.ConclusionsViral persistence during HAART is partly a result of continued low-level replication, calling for more active regimens. IL-2 accelerates the normalization of CD4 T cell counts but does not impact on virus production or latency.

ISSN:0269-9370    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

ObjectiveTo develop a SIV–rhesus macaque (Rh) model of AIDS that more closely approximates HIV pathogenesis in humans.DesignThe pathogenesis of SIV was compared in two different types of Rh, the Chinese (Ch) and Indian (Ind) subspecies.MethodsCh Rh and Ind Rh origin were identified genetically and infected with the SIVmac239molecular clone. Plasma viral loads, depletion of intestinal lymphocytes with memory phenotype, humoral immune responses and CD4/CD8 cell ratios were compared during acute and steady-state periods of infection.ResultsPlasma viral loads from 7 days after infection through 240 days were significantly lower in Rh of Ch origin compared with Ind Rh. Viral loads in Ch Rh were closer to viral loads observed in untreated humans infected with HIV-1. Depletion of intestinal effector cells was less evident in SIV-infected Ch Rh compared with Ind Rh. An index of intestinal pathogenesis was devised that closely paralleled viral load and severity of infection. There were no rapid progressors to AIDS among 10 Ch Rh. In contrast, three of four Ind Rh progressed rapidly to AIDS.ConclusionsCompared with Ind Rh, SIVmacpathogenesis in Ch Rh was closer to HIV-1 infections in untreated adult humans. The differences were statistically significant. The Ch Rh subspecies is a suitable AIDS model and may have advantages over the rapid and highly pathogenic Ind Rh model. Moreover, Ind Rh supplies are limited and use of Ch Rh provides a new resource.

ISSN:0269-9370    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

ObjectivePerforin is an important component of the death machinery of cytotoxic T cells (CTL). To evaluate functional differences between HIV- and cytomegalovirus (CMV)-specific CTL of coinfected patients, the frequencies of the respective perforin-expressing T cells were analysed in a rapid whole blood assay.MethodsWhole blood of HIV- and CMV-infected individuals was specifically stimulated by HIV-1 Pr55gagor complete CMV antigen, and activation-induced intracellular cytokine and perforin expression in CD8 T cells was analysed by flow cytometry.ResultsPerforin-expressing HIV-1- and CMV-specific CD8 T cells can be quantified simultaneously. Within a patient, the frequency of such HIV-specific CD8 T cells in peripheral blood was lower than the frequency of the respective CMV-specific cells. The number of the perforin-expressing HIV-specific CD8 T cells inversely correlated with the peripheral blood CD4 T cell count.ConclusionsThe differential fractions of perforin-expressing virus-specific CD8 T cells in HIV and CMV double infection might be caused by differences in priming and trafficking to or from replication sites. However, without knowing the underlying mechanism, the fraction of perforin-expressing HIV-specific CD8 T cells provides another surrogate marker for disease progression.

ISSN:0269-9370    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

ObjectivesTo determine the impact ofPlasmodium falciparummalaria coinfection and its treatment on cellular reservoirs of viral replication in HIV-1-infected persons and to relate this to changes in systemic immune activation.MethodsPlasma samples were obtained from HIV-1-infected individuals (n = 10) at diagnosis of acute malaria, 4 weeks after parasite clearance and from HIV-infected aparasitemic controls (n = 10). Immunomagnetic HIV-1 capture analysis was used to determine the cellular origin of cell-free virus particles present in all 30 plasma samples and indices of immune activation were measured using enzyme-linked immunosorbent assays.ResultsCompared with controls, the detectable proportion of HIV-1 particles derived from CD14 macrophages and CD26 lymphocytes was increased in persons with acute malaria coinfection and correlated with markedly increased plasma concentrations of both proinflammatory cytokines and soluble markers of macrophage and lymphocyte activation. Parasite clearance following treatment with antimalarial drugs resulted in decreased detection of HIV-1 particles derived from the CD14 macrophage cell subset and correlated with a marked diminution in systemic immune activation.ConclusionsAcuteP. falciparummalaria coinfection impacts virus–host dynamics in HIV-1-infected persons at the cellular level, notably showing a reversible induction of HIV-1 replication in CD14 macrophages that is associated with changes in immune activation.

ISSN:0269-9370    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

ObjectiveTo assess temporal changes in prevalence of transmitted HIV-1 drug resistance in a homogeneous cohort of newly infected individuals.MethodsPretreatment genotypic and phenotypic drug resistance was tested in 154 subjects with primary HIV-1 infection identified between 1995 and 2001 (group A; n = 76) and 1999 and 2001 (group B; n = 78). Sequence analysis was assessed by population-based sequencing. Virus susceptibility to antiretroviral agents was determined by the PhenoSense assay (ViroLogic).ResultsThe frequency of resistance-associated mutations in protease (PR) and reverse transcriptase (RT) genes increased from 13.2% (1995–1998) to 19.7% (1999–2001). Although the overall prevalence of viruses with phenotypic resistance did not vary (1995–1998, 10.0%; 1999–2001, 10.8%), the distribution of drug classes changed [nucleoside RT inhibitor (NRTI): 8.3% to 2.7%; non-NRTI: 5.0% to 8.1%; protease inhibitors (PI): 1.7% to 5.4%]. The decrease of phenotypic resistance to NRTI in 1999–2001 was caused by the absence of transmitted lamivudine-resistant variants. Phenotypically susceptible variants with aspartic acid or serine residues at position 215 of RT (5.3%;P= 0.04) instead emerged. Hypersusceptibility to PI decreased from 18.3% to 5.4% (P= 0.02) while the amino acid substitutions in PR increased over time: M36I (6.6% to 19.7%) and A71V/T (3.9% to 15.8%).ConclusionsThere was an increase in the number of HIV-1 variants with both genotypic and phenotypic resistance to non-NRTI and PI over time. Furthermore, viruses with altered genotypes compatible with thymidine analogue or PI exposure but susceptible phenotypes were seen in 1999–2001. The latter findings suggest transmission of viruses from subjects who have either changed or discontinued therapy.

ISSN:0269-9370    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

ObjectivesTo determine the prevalence and prognostic significance of intermittent viraemia (IV) in patients who attained an undetectable viral load (VL) < 400 copies/ml within 6 months on highly active antiretroviral therapy (HAART).MethodsRetrospective analysis of viral load rebound ⩾ 400 copies/ml and CD4 cell counts rise for 765 patients followed for ⩾ 12 months following initial VL undetectability, comparing the 226 (29.5%) who maintained an undetectable VL for > 1 year from initiation of HAART and 122 (15.9%) who had one or more episodes of IV. Genotypic resistance was evaluated at the time of the first episode of IV ⩾ 2000 copies/ml.ResultsPatients with IV had a threefold higher rate of sustained virological rebound [hazards ratio (HR), 3.15; 95% confidence interval (CI), 1.72–5.77;P< 0.001). For patients with and without IV, the Kaplan–Meier estimates at 24 and 36 months after initiation of HAART were 19.3% (95% CI, 8.9–21.5) versus 7.7% (95% CI, 4.5–13.0) and 31.6% (95% CI, 21.8–44.2) versus 12.9% (95% CI, 7.5–21.5), respectively (P< 0.001). The median CD4 cell count rise at 18 and 24 months was significantly lower in those with IV than in those without: 138 [interquartile range (IQR), 58–221] versus 224 × 106cells/l (IQR, 119–357) (P= 0.0001) and 200 (IQR, 89–294) versus 260 × 106cells/l (IQR, 125–384) (P= 0.003), respectively. In a subgroup of 16 patients, genotypic resistance mutations were found in the reverse transcriptase gene for five (31%) and in the protease gene in one. A probable contributing factor/event was identified for most patients with IV, such as poor adherence (42.6%), intercurrent infection (26.2%) or drug interaction (6.8%).ConclusionsPatients with IV > 400 copies/ml are three times more likely to experience sustained viral rebound and to have an impaired CD4 cell rise relative to those who maintain undetectable VL. This supports the adoption of a more pro-active approach to treatment intensification and the need for caution with structured treatment interruptions.

ISSN:0269-9370    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

ObjectivesTo determine the potential for secondary HIV transmission among newly HIV-infected men who have sex with men (MSM) during their HIV antibody seroconversion period, and for the 12 months after seroconversion.DesignA cohort study.MethodsRisk assessment questionnaires administered before receipt of the first positive HIV antibody result, plasma and seminal viral load measurements, and risk assessments one month and quarterly after receipt of the first HIV-positive test, and generalized estimating equation modelling techniques to analyse behavioral trends.ResultsOf 66 seroconverters, more than half reported unprotected anal intercourse (UAI) with HIV-negative or unknown-serostatus partners during seroconversion, with 27% reporting insertive UAI with an HIV-negative partner. The initial median plasma viral load was 4.6 log/ml, the median seminal viral load was 2.7 log/ml, suggesting a high level of infectiousness. Compared with risk behavior during seroconversion, UAI with HIV-negative or unknown-serostatus partners was reduced after the receipt of positive antibody results; however, a substantial proportion of participants reported high-risk behaviors for transmission for 12 months of follow-up. After learning of their HIV infection, recent seroconverters did not reduce the risk of secondary transmission by engaging in proportionally more high-risk practices with HIV-infected partners (compared with HIV-negative or unknown-serostatus partners), or engaging in proportionally more receptive compared with insertive UAI.ConclusionSubstantial potential exists for secondary HIV transmission during and for one year after HIV seroconversion. Receipt of an HIV-positive test is associated with a significant reduction in risk behavior, reinforcing the need to identify and counsel recently HIV-infected MSM.

ISSN:0269-9370    

出版商:OVID    

年代:2002

数据来源: OVID