RESUMO
HIV-1 entry into target cells influences several aspects of HIV-1 pathogenesis, including viral tropism, HIV-1 transmission and disease progression, and response to entry inhibitors. The evolution from CCR5- to CXCR4-using strains in a given human host is still unpredictable. Here we analyzed timing and predictors for coreceptor evolution among recently HIV-1-infected individuals. Proviral DNA was longitudinally evaluated in 66 individuals using Geno2pheno[coreceptor] Demographics, viral load, CD4+ and CD8+ T cell counts, CCR5Δ32 polymorphisms, GB virus C (GBV-C) coinfection, and HLA profiles were also evaluated. Ultradeep sequencing was performed on initial samples from 11 selected individuals. A tropism switch from CCR5- to CXCR4-using strains was identified in 9/49 (18.4%) individuals. Only a low baseline false-positive rate (FPR) was found to be a significant tropism switch predictor. No minor CXCR4-using variants were identified in initial samples of 4 of 5 R5/non-R5 switchers. Logistic regression analysis showed that patients with an FPR of >40.6% at baseline presented a stable FPR over time whereas lower FPRs tend to progressively decay, leading to emergence of CXCR4-using strains, with a mean evolution time of 27.29 months (range, 8.90 to 64.62). An FPR threshold above 40.6% determined by logistic regression analysis may make it unnecessary to further determine tropism for prediction of disease progression related to emergence of X4 strains or use of CCR5 antagonists. The detection of variants with intermediate FPRs and progressive FPR decay over time not only strengthens the power of Geno2pheno in predicting HIV tropism but also indirectly confirms a continuous evolution from earlier R5 variants toward CXCR4-using strains.IMPORTANCE The introduction of CCR5 antagonists in the antiretroviral arsenal has sparked interest in coreceptors utilized by HIV-1. Despite concentrated efforts, viral and human host features predicting tropism switch are still poorly understood. Limited longitudinal data are available to assess the influence that these factors have on predicting tropism switch and disease progression. The present study describes longitudinal tropism evolution in a group of recently HIV-infected individuals to determine the prevalence and potential correlates of tropism switch. We demonstrated here that a low baseline FPR determined by the Geno2pheno[coreceptor] algorithm can predict tropism evolution from CCR5 to CXCR4 coreceptor use.
Assuntos
Vírus GB C/metabolismo , Infecções por HIV/transmissão , HIV-1/metabolismo , Receptores CCR5/metabolismo , Receptores CXCR4/metabolismo , Receptores de HIV/metabolismo , Tropismo Viral/fisiologia , Adulto , Contagem de Linfócito CD4 , Relação CD4-CD8 , Coinfecção/virologia , Reações Falso-Positivas , Feminino , Infecções por HIV/virologia , HIV-1/genética , Humanos , Masculino , Pessoa de Meia-Idade , Carga Viral/imunologia , Ligação Viral , Internalização do Vírus , Adulto JovemRESUMO
We previously reported a high prevalence of HIV-1 infection in Warao Amerindians from Venezuela due to the rapid spread of a single B subtype strain. In this study we evaluated the coreceptor use of the HIV-1 strains infecting this Amerindian community. Sequences of the HIV-1 V3 loop from 56 plasma samples were genotyped for coreceptor use. An extremely high frequency of CXCR4 strains was found among HIV-1-infecting Waraos (47/49, 96%), compared to HIV-1 strains infecting the non-Amerindian Venezuelan population (35/79, 44%, p < 0.00001). Evolutionary analysis showed that a significant number of infections occurred between 1 and 12 months before collection and that a great proportion (50-70%) of HIV-1 transmissions occurred within the very early phase of infection (≤12 months). This is consistent with an initial infection dominated by an X4 strain or a very rapid selection of X4 variants after infection. This Amerindian population also exhibits the highest prevalence of tuberculosis in Venezuela, being synergistically bad prognostic factors for the evolution of morbidity and mortality in this vulnerable population.
Assuntos
Epidemias , Infecções por HIV/epidemiologia , Infecções por HIV/virologia , HIV-1/classificação , HIV-1/genética , Receptores CXCR4/metabolismo , Receptores de HIV/metabolismo , Feminino , Genótipo , Proteína gp120 do Envelope de HIV/genética , HIV-1/isolamento & purificação , HIV-1/fisiologia , Humanos , Indígenas Centro-Americanos , Masculino , Plasma/virologia , Análise de Sequência de DNA , Venezuela/epidemiologiaRESUMO
BACKGROUND: The interaction of HIV-1 and target cells involves sequential binding of the viral gp120 Env protein to the CD4 receptor and a chemokine co-receptor (either CCR5 or CXCR4). CCR5 antagonists have proved to be an effective salvage therapy in patients with CCR5 using variants (R5) but not with variants capable of using CXCR4 (×4) phenotype. Thus, it is critically important to determine cellular tropism of a country's circulating HIV strains to guide a management decision to improve treatment outcome. In this study, we report the prevalence of R5 and ×4 HIV strains in 45 proviral DNA massively parallel sequencing "MPS" data from recently infected Brazilian blood donors. METHODS: The MPS data encompassing the tropism-related V3 loop region of the HIV-1 env gene was extracted from our recently published HIV-1 genomes sequenced by a paired-end protocol (Illumina). HIV-1 tropism was inferred using Geno2pheno[coreceptor] algorithm (3.5 % false-positive rate). V3 net charge and 11/25 rules were also used for coreceptor prediction. RESULTS: Among the 45 samples for which tropism were determined, 39 were exclusively R5 variants, 5 ×4 variants, and one dual-tropic or mixed (D/M) populations of R5 and ×4 viruses, corresponding to 86.7, 11.1 and 2.2 %, respectively. Thus, the proportion of all blood donors that harbor CXCR4-using virus was 13.3 % including individuals with D/M-tropic viruses. CONCLUSIONS: The presence of CCR5-tropic variants in more than 85 % of our cohort of antiretroviral-naïve blood donors with recent HIV-1 infection indicates a potential benefit of CCR5 antagonists as a therapeutic option in Brazil. Therefore, determination of viral co-receptor tropism is an important diagnostic prerequisite.
Assuntos
Doadores de Sangue , Infecções por HIV/virologia , HIV-1/genética , HIV-1/fisiologia , Receptores de HIV/metabolismo , Tropismo Viral , Ligação Viral , Brasil , HIV-1/isolamento & purificação , Sequenciamento de Nucleotídeos em Larga Escala , HumanosRESUMO
Feline immunodeficiency virus (FIV) and the T cell-tropic strains of human immunodeficiency virus type 1 (HIV-1) share the use of the chemokine receptor CXCR4 for cell entry. To study this process further we developed a cell surface binding assay based on the expression of a soluble version of the FIV SU C-terminally tagged with the influenza virus hemagglutinin epitope (HA). The specificity of the assay was demonstrated by the following evidence: (1) the SU-HA protein bound to HeLa cells that express CXCR4 but not to MDCK cells that lack this chemokine receptor; and (2) binding of the SU-HA to HeLa cells was blocked by incubation with the CXCR4 antagonist AMD3100 as well as with the anti-CXCR4 monoclonal antibody (MAb) 12G5. Deletion of the V3 region from the FIV SU glycoprotein abolished its ability to bind CXCR4-expressing cells. Remarkably, substitution of the V3 domain of the FIV SU by the equivalent region of the HIV-1 NL4-3 isolate resulted in efficient cell surface binding of the chimeric SU protein to CXCR4. Moreover, transfection of MDCK cells with a plasmid encoding human CXCR4 allowed the association of the chimeric SU-HA glycoprotein to the transfected cells. Interestingly, while cell binding of the chimeric FIV-HIV SU was inhibited by an anti-HIV-1 V3 MAb, its association with CXCR4 was found to be resistant to AMD3100. Of note, the chimeric FIV-HIV Env glycoprotein was capable of promoting CXCR4-dependent cell-to-cell fusion.
Assuntos
Glicoproteínas/genética , HIV-1/genética , Vírus da Imunodeficiência Felina/fisiologia , Receptores CXCR4/metabolismo , Receptores de HIV/metabolismo , Proteínas do Envelope Viral/genética , Ligação Viral , Produtos do Gene env do Vírus da Imunodeficiência Humana/genética , Animais , Linhagem Celular , Humanos , Vírus da Imunodeficiência Felina/genética , Recombinação GenéticaRESUMO
BACKGROUND: Vicriviroc, a novel HIV CCR5 antagonist, demonstrated significant efficacy and favorable tolerability in phase II trials in treatment-experienced subjects, supporting further evaluation in phase III studies. METHODS: Two identical double-blind, placebo (PBO)-controlled trials in CCR5-tropic HIV-infected subjects with documented resistance to two antiretroviral classes were conducted. Subjects were randomized to vicriviroc 30 mg QD (N = 571) or PBO (N = 286) with open-label optimized background therapy (OBT) containing ≥2 fully active antiretroviral drugs. The primary endpoint was percentage of subjects with <50 copies/mL HIV RNA at 48 weeks. It was analyzed in a logistic regression with treatment (vicriviroc + OBT/PBO + OBT), use of enfuvirtide in baseline OBT (yes/no), and baseline HIV RNA (≤100,000/>100,000 copies/mL) as covariates. In addition, a pre-planned analysis to examine other efficacy and safety endpoints was conducted. RESULTS: Baseline characteristics of the pooled mITT population (vicriviroc, n = 486; PBO, n = 235) included mean HIV RNA of 4.6 log(10) copies/mL and mean CD4 count of 257 cells/µL. Approximately 60% of subjects received ≥3 active drugs in the OBT. The percentage of subjects with <50 copies/mL HIV RNA was not significantly different between vicriviroc and PBO at week 48 (64% vs 62%, p = 0.6). However, in subjects receiving ≤2 active drugs in their OBT, the proportion achieving <50 copies/mL HIV RNA was higher in those receiving vicriviroc compared with PBO (70% vs 55%, p = 0.02). CONCLUSIONS: The studies failed to show significant efficacy gains when vicriviroc was added to OBT. However, given the efficacy results of earlier vicriviroc trials and other CCR5 antagonist, studies are needed to define the role of this class of drugs in the treatment of HIV. Clinical trial identifier: http://www.clinicaltrial.gov/: VICTOR-E3 (NCT00523211) and VICTOR-E4 (NCT00474370).
Assuntos
Fármacos Anti-HIV/administração & dosagem , Infecções por HIV/tratamento farmacológico , HIV-1/genética , Piperazinas/administração & dosagem , Pirimidinas/administração & dosagem , Receptores CCR5/metabolismo , Receptores de HIV/metabolismo , Adulto , Método Duplo-Cego , Feminino , Infecções por HIV/virologia , HIV-1/isolamento & purificação , HIV-1/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Placebos/administração & dosagem , RNA Viral/sangue , Resultado do Tratamento , Carga Viral , Viremia/virologiaRESUMO
Chemokine receptor expression may vary dramatically among cell subsets. Therefore, the stage of differentiation and the lineage of CD4 cells may profoundly affect their susceptibility to infection by human immunodeficiency virus type 1 (HIV-1). However, the mechanisms of coreceptor competition for association with HIV-1 glycoproteins remain unknown. Here, we propose mathematical models that address the interdependence of the concentrations of CD4 and CCR5 for efficient infection by M-tropic HIV-1 as well as additional complications originated by coreceptor competition caused by posttranslational modifications that positively or negatively affect the coreceptor ability to form complexes with CD4 and/or HIV-1 envelope. Furthermore, since CCR5 and CXCR4 expression on human leukocytes designate these cells as HIV-1 potential targets, the expression of the major HIV-1 coreceptors are also dynamically modeled/quantified as function of the stage of cell differentiation. Results show that although coreceptor competition degree has limited influence on R5 strain infectivity, the infectivity of CXCR4-using isolates strongly depends on the CD4 expression, according to the coreceptor competition model proposed in Lee et al. [J. Virol. 74(11) (2000) 5016]. Understanding the role of in vivo alterations in CD4, CCR5 and CXCR4 densities on HIV-1 cell entry may help the development of optimal control strategies for AIDS pathogenesis.
Assuntos
HIV-1/patogenicidade , Leucócitos Mononucleares/virologia , Modelos Biológicos , Receptores CCR5/fisiologia , Receptores CXCR4/fisiologia , Algoritmos , Antígenos CD4/metabolismo , Antígenos CD4/fisiologia , Linfócitos T CD8-Positivos/metabolismo , Linfócitos T CD8-Positivos/fisiologia , Linfócitos T CD8-Positivos/virologia , Linhagem da Célula , Expressão Gênica , Infecções por HIV/sangue , Infecções por HIV/fisiopatologia , Infecções por HIV/virologia , Humanos , Leucócitos Mononucleares/metabolismo , Leucócitos Mononucleares/fisiologia , Macrófagos/metabolismo , Macrófagos/fisiologia , Macrófagos/virologia , Monócitos/metabolismo , Monócitos/fisiologia , Monócitos/virologia , Receptores CCR5/sangue , Receptores CCR5/genética , Receptores CXCR4/sangue , Receptores CXCR4/genética , Receptores de HIV/metabolismo , Receptores de HIV/fisiologia , Linfócitos T/metabolismo , Linfócitos T/fisiologia , Linfócitos T/virologiaRESUMO
In addition to the CD4 molecule that binds to the human immunodeficiency virus type-1 (HIV-1) envelope glycoprotein gp120, productive HIV-1 infection requires interaction with cellular receptors for alpha- or beta- chemokines (CXCR4 and CCR5 respectively). Isolates of HIV-1 exhibit different tropism depending on the chemokine receptor type that they use to infect their cellular targets. HIV-1 strains that use preferentially CCR5 are known as R5 strains. They are more frequently found in asymptomatic individuals during the initial stages of the disease and are involved in the transmision of infection from mother to child. HIV-1 species using CXCR4 (X4 strains) are observed mainly in patients with advanced disease. While X4 isolates are associated with syncitium formation, in general R5 strains are not. Interaction of X4 and R5 with their specific receptors is necessary to establish productive HIV-1 infection and trigger a series of intracellular signals. Modulation of CXCR4 and CCR5 expression after HIV-1 infection is one of the results of such interaction and may have important consequences on the course of the infection. Down regulation of CCR5 and CXCR4 after HIV-1 infection could be the result of indirect events linked to HIV-1 infection, such as the induction of alpha- or beta-chemokines competing with the virions for receptor binding. They could also reflect direct effects of HIV-1 on chemokine-receptor turnover. In this review, the mechanisms of modulation of CXCR4 and CCR5 expression after HIV-1 infection will be discussed.
Assuntos
Regulação da Expressão Gênica , Infecções por HIV/virologia , HIV-1/imunologia , HIV-1/fisiologia , Receptores CCR5/metabolismo , Receptores CXCR4/metabolismo , Receptores de HIV/metabolismo , Quimiocinas CC/metabolismo , Quimiocinas CXC/metabolismo , Regulação para Baixo , Proteína gp120 do Envelope de HIV/fisiologia , Proteína gp41 do Envelope de HIV/fisiologia , Humanos , Receptores CCR5/genética , Receptores CCR5/imunologia , Receptores CXCR4/genética , Receptores CXCR4/imunologia , Receptores de HIV/genética , Receptores de HIV/imunologiaRESUMO
Chemokine receptors are G protein-coupled receptors that mediate migration and activation of leukocytes as an important part of a protective immune response to injury and infection. In addition, chemokine receptors are used by HIV-1 to infect CD4 positive cells. The structural bases of chemokine receptor recognition and signal transduction are currently being investigated. High-resolution X-ray diffraction and NMR spectroscopy of chemokines indicate that all these peptides exhibit a common folding pattern, in spite of its low degree of primary-sequence homology. Chemokines' functional motifs have been identified by mutagenesis studies, and a possible mechanism for receptor recognition and activation is proposed, but high-resolution structure data of chemokine receptors is not yet available. Studies with receptor chimeras have identified the putative extracellular domains as the major selectivity determinants. Single-amino acid substitutions in the extracellular domains produce profound changes in receptor specificity, suggesting that motifs in these domains operate as a restrictive barrier to a common activation motif. Similarly HIV-1 usage of chemokine receptors involve interaction of one or more extracellular domains of the receptor with conserved and variable domains on the viral envelope protein gp 120, indicating a highly complex interaction. Elucidating the structural requirements for receptor interaction with chemokines and with HIV-1 will provide important insights into understanding the mechanisms of chemokine recognition and receptor activation. In addition, this information can greatly facilitate the design of effective immunomodulatory and anti-HIV-1 therapeutic agents.
Assuntos
Linfócitos T CD4-Positivos/virologia , HIV/metabolismo , Receptores de Quimiocinas/química , Humanos , Conformação Proteica , Receptores de Quimiocinas/metabolismo , Receptores de Quimiocinas/fisiologia , Receptores de HIV/metabolismo , Relação Estrutura-AtividadeRESUMO
Chemokine receptors are G protein-coupled receptors that mediate migration and activation of leukocytes as an important part of a protective immune response to injury and infection. In addition, chemokine receptors are used by HIV-1 to infect CD4 positive cells. The structural bases of chemokine receptor recognition and signal transduction are currently being investigated. High-resolution X-ray diffraction and NMR spectroscopy of chemokines indicate that all these peptides exhibit a common folding pattern, in spite of its low degree of primary-sequence homology. Chemokines' functional motifs have been identified by mutagenesis studies, and a possible mechanism for receptor recognition and activation is proposed, but high-resolution structure data of chemokine receptors is not yet available. Studies with receptor chimeras have identified the putative extracellular domains as the major selectivity determinants. Single-amino acid substitutions in the extracellular domains produce profound changes in receptor specificity, suggesting that motifs in these domains operate as a restrictive barrier to a common activation motif. Similarly HIV-1 usage of chemokine receptors involves interaction of one or more extracellular domains of the receptor with conserved and variable domains on the viral envelope protein gp 120, indicating a highly complex interaction. Elucidating the structural requirements for receptor interaction with chemokines and with HIV-1 will provide important insights into understanding the mechanisms of chemokine recognition and receptor activation. In addition, this information can greatly facilitate the design of effective inmunomodulatory and anti-HIV-1 therapeutic agents