enfuvirtide and Viremia

Topics: Clinical Trials as Topic; Drug Resistance, Viral; Enfuvirtide; HIV Envelope Protein gp41; HIV Fusion Inhibitors; HIV Infections; HIV-1; Humans; Mutation; Peptide Fragments; Viremia

In HIV-1-infected patients receiving antiretroviral therapy (ART), the relationship between residual viraemia and ex vivo recovery of infectious virus from latently infected CD4 cells is uncertain.. We measured residual viraemia (HIV-1 RNA copies/ml) by single-copy assay (SCA) and the latent reservoir by infectious virus recovery from resting memory CD4 cells (infectious units per million cells [IUPM]) in patients who initiated ART. We assessed immune activation by measuring CD38 expression on T-cells.. Ten patients who initiated ART and maintained a plasma HIV-1 RNA level < 200 copies/ml had residual viraemia and IUPM measured every 24 weeks. Five of 10 patients had longitudinal IUPM measured at weeks 24-96; the remainder had IUPM measured 1-3 times over 24-72 weeks. Analyses of 29 paired measurements revealed a positive association between level of residual viraemia and IUPM (0.56 higher log10 HIV-1 RNA copies/ml per 1 log10 higher IUPM; P = 0.005). Residual viraemia level was positively associated with CD38 density and percentage on CD8+ T-cells in concurrent samples and with pre-ART HIV-1 RNA levels.. In patients with HIV-1 RNA levels < 200 copies/ml 24-96 weeks after initiating ART, the level of viraemia is positively associated with infectious virus recovery from resting memory CD4 cells. Whether this association persists after longer-term suppressive ART needs to be determined. If additional studies show that residual viraemia measured by SCA reflects the size of the latent reservoir in patients who have had virological suppression for longer periods of time, this could facilitate testing of potentially curative strategies to reduce this important reservoir.

Topics: ADP-ribosyl Cyclase 1; Anti-HIV Agents; CD4-Positive T-Lymphocytes; Enfuvirtide; Gene Expression; HIV Envelope Protein gp41; HIV Infections; HIV-1; Humans; Immunologic Memory; Peptide Fragments; RNA, Viral; Viral Load; Viremia

Human immunodeficiency virus (HIV) infection that persists despite antiretroviral therapy (ART) is a daunting problem. Given the limited evidence that resting CD4+ T cell infection (RCI) is affected by the histone deacetylase (HDAC) inhibitor valproic acid (VPA), we measured the stability of RCI and residual viremia in patients who added VPA with or without raltegravir (RAL), or enfuvirtide (ENF) with or without VPA, to standard ART.. Patients with plasma HIV RNA<50 c/mL added sustained-release VPA (Depakote ER) twice daily, RAL 400 mg twice daily, or ENF 90 mcg twice daily. Change in RCI was measured by outgrowth assays. Low-level viremia was quantitated by single-copy plasma HIV RNA assay (SCA).. In three patients on standard ART a depletion of RCI was observed after 16 weeks of VPA, but this effect waned over up to 96 weeks of further VPA. In two patients ENF added to stable ART had no effect on RCI. Simultaneous intensification with ENF and addition of VPA had no effect on RCI frequency in one patient, and resulted in a 46% decline in a second. No significant depletion of RCI (>50%) was seen in six volunteers after the addition of RAL and VPA. In 4 of the 6 patients this lack of effect might be attributed to intermittent viremia, low VPA levels, or intermittent study therapy adherence. Overall, there was no effect of the addition of RAL or ENF on low-level viremia measured by SCA.. The prospective addition of VPA and RAL, VPA and ENF, or ENF failed to progressively reduce the frequency of RCI, or ablate intermittent and low-level viremia. New approaches such as more potent HDAC inhibition, alone or in combination with intensified ART or other agents that may disrupt proviral latency must be pursued.

Topics: Antiretroviral Therapy, Highly Active; CD4-CD8 Ratio; CD4-Positive T-Lymphocytes; Drug Administration Schedule; Drug Therapy, Combination; Enfuvirtide; Enzyme Inhibitors; Histone Deacetylase Inhibitors; HIV Envelope Protein gp41; HIV Infections; HIV-1; Humans; Male; Peptide Fragments; Prospective Studies; Pyrrolidinones; Raltegravir Potassium; RNA, Viral; Treatment Outcome; Valproic Acid; Viremia

Antiretroviral treatment (ART) significantly reduces cerebrospinal fluid (CSF) HIV-1 RNA levels and residual viremia is less frequently found in CSF than in blood. However, persistent intrathecal immunoactivation is common, even after several years of ART. To investigate whether low-level CSF viremia and residual immunoactivation within the central nervous system (CNS) derive from ongoing local viral replication, we conducted a study of treatment intensification in patients on effective ART.. Ten patients on ART with plasma HIV RNA <50 copies per milliliter for >18 months were included. Intensification was given for in total 8 weeks: 4 weeks with maraviroc or lopinavir/ritonavir (good CNS penetration), and 4 weeks with enfuvirtide (poor CNS penetration). Lumbar punctures were performed 4 weeks before, at intensification commencement, at switchover after 4 weeks, at the conclusion of, and 4 weeks after the intensification period.. No significant changes in HIV RNA, neopterin, β2-microglobulin, immunoglobulin G index, albumin ratio, and CD4(+) T-cell count were observed, either in CSF or blood, neither before, during, nor after the intensification periods.. ART intensification did not reduce residual CSF HIV RNA levels or intrathecal immunoactivation in patients on ART. These findings do not support an ongoing viral replication in CNS.

Topics: Adult; Albumins; Anti-HIV Agents; Antiretroviral Therapy, Highly Active; CD4 Lymphocyte Count; CD4-Positive T-Lymphocytes; Central Nervous System Infections; Cross-Over Studies; Cyclohexanes; Enfuvirtide; Female; HIV Envelope Protein gp41; HIV Infections; HIV-1; Humans; Immunoglobulin G; Lopinavir; Male; Maraviroc; Middle Aged; Neopterin; Peptide Fragments; Polymerase Chain Reaction; Ritonavir; RNA, Viral; Triazoles; Viral Load; Viremia; Virus Replication

Four heavily antiretroviral-experienced HIV-infected patients had significant plasma HIV-RNA reductions (>1 log) after beginning an Enfuvirtide (ENF)-based rescue regimen. However, all had viral rebound shortly thereafter, sustaining high levels of plasma viremia over 80 weeks. These patients developed rapidly genotypic and phenotypic resistance to ENF. Mutations within the HR1 env region were selected (N43D in three and G36V/D in one), resulting in high-level phenotypic resistance to ENF. Interestingly, two patients had a sustained CD4+ T-cell increase and two maintained stable CD4+ T-cell counts despite virologic failure under ENF. The possible mechanisms involved in this response were examined. Changes in virus tropism from R5 to R5/X4 were observed in two patients, in parallel with increases in ENF phenotypic resistance. Low levels of T-cell activation, T-cell turnover, and cytotoxic T lymphocyte (CTL) activity were found in all four patients. An overall increase in the proportion of viruses released from cells of the macrophage lineage was observed. In summary, single mutations at the HR1 env region result in significant loss of susceptibility to ENF. Despite virologic failure, these patients may maintain elevated CD4+ counts through a reduction in their overall immune activation.

Topics: Amino Acid Sequence; Amino Acid Substitution; Antiretroviral Therapy, Highly Active; CD4 Lymphocyte Count; Drug Resistance, Viral; Enfuvirtide; Gene Products, pol; Genes, env; Genes, pol; Genes, Viral; HIV; HIV Envelope Protein gp41; HIV Fusion Inhibitors; HIV Infections; Humans; Lymphocyte Activation; Macrophages; Molecular Sequence Data; Mutation, Missense; Peptide Fragments; Receptors, CCR5; Receptors, CXCR4; RNA, Viral; Salvage Therapy; T-Lymphocytes, Cytotoxic; Viremia

The gp41-encoding sequence of the env gene contains in two separate regions the Rev-responsive elements (RRE) and the alternative open reading frame of the second exon of the regulatory protein Rev. The binding of Rev to the RRE allows the transport of unspliced/singly spliced viral mRNAs out of the nucleus, an essential step in the life cycle of human immunodeficiency virus type 1 (HIV-1). In this study, we have investigated whether the fusion-inhibitor enfuvirtide (ENF) can induce mutations in Rev and if these mutations correlate with the classical ENF resistance gp41 mutations and with viremia and CD4 cell count. Specific Rev mutations were positively associated with ENF treatment and significantly correlated with classical ENF resistance gp41 mutations. In particular, a cluster was observed for the Rev mutations E57A (E57A(rev)) and N86S(rev) with the ENF resistance gp41 mutations Q40H (Q40H(gp41)) and L45M(gp41). In addition, the presence at week 48 of the E57A(rev) correlates with a significant viremia increase from baseline to week 48 and with a CD4 cell count loss from baseline to week 48. By modeling the RRE structure, we found that the Q40(gp41) and L45(gp41) codons form complementary base pairs in a region of the RRE involved in Rev binding. The conformation of this Rev-binding site is disrupted when Q40H(gp41) and L45M(gp41) occur alone while it is restored when both mutations are present. In conclusion, our study shows that ENF pressure may also affect both Rev and RRE structures and can provide an excellent example of compensatory evolution. This highlights the multiple roles of ENF (and perhaps other entry inhibitors) in modulating the correct interplay between the different HIV-1 genes and proteins during the HIV-1 life cycle.

Topics: Adult; Base Sequence; CD4 Lymphocyte Count; Drug Resistance, Viral; Enfuvirtide; Female; Genes, env; HIV Envelope Protein gp41; HIV Fusion Inhibitors; HIV-1; Humans; Male; Middle Aged; Molecular Sequence Data; Mutation; Nucleic Acid Conformation; Peptide Fragments; rev Gene Products, Human Immunodeficiency Virus; Viremia

Raltegravir is a potential treatment option for virologically suppressed HIV-1 infected patients on enfuvirtide with injection site reactions.. To characterize safety and efficacy of an enfuvirtide to raltegravir switch including changes in T-cells, quality of life, and residual viremia.. In patients with viral load <50 copies/mL and injection site reactions, enfuvirtide was switched to raltegravir without additional changes to the antiretroviral regimen. Virologic failure was defined as a viral load >1000 copies/mL or two consecutive viral load measurements between 50 and 1000 copies/mL (low-level viremia). Over the 24 week study, we compared changes in T-cells, injection site reactions, quality of life, and residual viremia, as measured through the single-copy assay which can detect plasma virus down to a single copy, using paired t-tests.. Fourteen patients with a median CD4+ T-cell count of 420 cells/microL were enrolled. After the switch, two patients experienced virologic failure due to confirmed low-level viremia. However, both patients subsequently were re-suppressed, one without any changes to his regimen. There was no change in CD4+ T-cell count. Injection site reactions resolved. However, there was little reported change in quality of life. The baseline median level of residual viremia was 6 copies/mL and did not change after the switch to raltegravir.. A switch to raltegravir in virologically suppressed patients on enfuvirtide is effective in maintaining immunologic and virologic control at 24 weeks but did not result in a change in residual viremia.

Topics: CD4 Lymphocyte Count; Enfuvirtide; HIV Envelope Protein gp41; HIV Fusion Inhibitors; HIV Infections; HIV-1; Humans; Male; Middle Aged; Peptide Fragments; Prospective Studies; Pyrrolidinones; Quality of Life; Raltegravir Potassium; Treatment Outcome; Viral Load; Viremia

Human immunodeficiency virus type 1 (HIV-1) gp41 is a crucial determinant for HIV-1 pathogenicity. We investigated the correlation of enfuvirtide (ENF)-associated gp41 mutational clusters with viroimmunological parameters, as well as the potential underlying mechanisms.. A total of 172 gp41 sequences and clinical follow-up data from 73 ENF-treated patients were analyzed monthly, from baseline to week 48.. There were 7 novel gp41 mutations positively associated with ENF treatment and correlated with classic ENF mutations. The ENF-associated clusters [V38A + N140I ] and [V 38A +T18A ] significantly correlated with an increase in CD4 cell count at week 48 ( an increase from baseline of 112 and 209 cells/microL, respectively), whereas [Q40H + L45M + 268A] significantly correlated with a decrease in CD4 cell count (-53 cells/microL), without a change in the level of viremia. Residues 38 and 18 are located complementarily to each other in the Rev-responsive element, whereas analysis of molecular dynamics showed that the copresence of [V38A + N140 I] abolishes the interaction between residue 38 and 145 important for stabilization of the 6-helix bundle. In contrast, T268A localizes in the gp41 calmodulin-binding domain responsible for gp41-induced CD4(+) T lymphocyte apoptosis.. Specific gp41 mutational clusters associated with ENF treatment significantly correlate with increases in CD4(+) cell count. Structural analysis suggests that this immunological gain is associated with mechanisms that act at both the protein level and the RNA level (even under conditions of virological failure). This result may help in the selection of patients who can benefit most from ENF treatment and represents a driving force for the design of the next generation of entry inhibitors.

Topics: Adult; Anti-HIV Agents; CD4 Lymphocyte Count; Drug Resistance, Viral; Enfuvirtide; Female; HIV Envelope Protein gp41; HIV Infections; HIV-1; Humans; Male; Middle Aged; Models, Molecular; Mutation, Missense; Peptide Fragments; Viral Load; Viremia

An unexpected dramatic immune recovery was observed in a patient with full-blown AIDS receiving enfuvirtide-based antiretroviral therapy after multiple treatment failures. A complex interplay of viral and host factors, including the control of X4 viruses and proviral burden, may favor immune restoration with HIV neutralizing activity, despite persistent viremia.

Topics: Acquired Immunodeficiency Syndrome; Adult; CD4 Lymphocyte Count; CD4-Positive T-Lymphocytes; Drug Resistance, Viral; Enfuvirtide; Female; HIV Envelope Protein gp41; HIV Fusion Inhibitors; HIV-1; Humans; Mutation; Neutralization Tests; Peptide Fragments; Time Factors; Viremia

Topics: Adenine; Adult; Anti-HIV Agents; Antiretroviral Therapy, Highly Active; Deoxycytidine; Emtricitabine; Enfuvirtide; HIV Envelope Protein gp41; HIV Infections; HIV-1; Humans; Lopinavir; Male; Organophosphonates; Peptide Fragments; Pyrimidinones; Ritonavir; Tenofovir; Viral Load; Viremia

To investigate gp41 variability and correlation with viro-immunological parameters in 54 HIV-1-infected patients receiving enfuvirtide added as single active drug to a failing regimen.. One hundred and two HIV-1 gp41 sequences and clinical follow-up from 54 enfuvirtide-treated patients were analysed from baseline to week 36 of treatment. The association of mutations with viraemia/CD4 count was assessed by Mann-Whitney test.. The addition of enfuvirtide to the failing regimen induced at week 4 a viraemia decrease from 5.1 to 4.3 log(10)/mL (P = 0.0002) and a CD4 increase from 48 to 106 cells/mm(3) (P = 0.008). While viraemia rebounded to 4.8 and 4.6 log(10)/mL at week 12 and 36, respectively, CD4 continued to increase to 136 cells/mm(3) at week 36. Enfuvirtide resistance mutations, rarely found at baseline, occurred in 45/54 (83.3%) enfuvirtide-treated patients. V38A/E were the most represented mutations at all time-points. The presence of V38A/E was significantly associated with a 4.5-fold CD4 increase from baseline to week 24 and with a 6-fold increase at week 36 (P = 0.004 and 0.02 compared without V38A/E, respectively), without significant correlation with viraemia. In contrast, Q40H + L45M (present in six enfuvirtide-treated patients at week 36) correlated with CD4 loss from baseline to week 36 (P = 0.02), without significant correlation with viraemia. Mutation N126K (observed in six enfuvirtide-treated patients, never found at baseline) abrogates the fourth gp41 glycosylation site and correlates with a 2.1-fold CD4 increase at week 24.. Specific enfuvirtide resistance mutations (V38A/E) are associated with a sustained CD4 increase, without remarkable effects upon viraemia. This CD4 recovery, due to virus- and immune-mediated mechanisms most probably not applicable to protease/reverse transcriptase inhibitors, is important for innovative therapeutic strategies.

Topics: Adult; CD4 Lymphocyte Count; Drug Resistance, Viral; Enfuvirtide; Female; Glycosylation; HIV Envelope Protein gp41; HIV Fusion Inhibitors; HIV Infections; HIV-1; Humans; Male; Middle Aged; Mutation; Peptide Fragments; Polymerase Chain Reaction; Sequence Analysis, DNA; Treatment Outcome; Viremia

To analyse the genetic changes in the gp41 protein in HIV-infected patients with detectable plasma viraemia receiving a long-term salvage enfuvirtide regimen.. We studied 13 heavily antiretroviral-experienced patients receiving a salvage regimen containing enfuvirtide. Substitutions in gp41 were analysed by population-based sequencing at baseline and longitudinally after the initiation of enfuvirtide treatment. To investigate sequence evolution we also analysed multiple gp41 clones from four selected patients. A Fisher's two-tailed test was used to assess the distribution of resistance-associated mutations in the clonal sequences.. Mutations at positions 36 and 38 in gp41 (HR1) emerged rapidly (median emerging time 10 weeks), but disappeared at subsequent timepoints in most of the patients. Amino acid changes did not accumulate over time, with no patient having more than two mutations in HR1 after 6 months of treatment. The mutation N43D was not observed together with changes at positions 36 or 38 in any patient. Clonal analysis showed that the three main gp41 resistance mutations were highly mutually exclusive (P < 0.001), being present in individual clones and constituting independent populations.. Substitutions at positions 36 and 38 are rapidly selected but disappear thereafter in HIV-1-infected patients failing an enfuvirtide-containing salvage therapy. We found a highly exclusive relationship between the three main enfuvirtide resistance-associated mutations (amino acids 36, 38 and 43), suggesting that the genetic evolution of HIV-1 gp41 protein is a dynamic and much more complex process than previously though.

Topics: Amino Acid Sequence; Drug Resistance, Viral; Enfuvirtide; Evolution, Molecular; Follow-Up Studies; HIV Envelope Protein gp41; HIV Fusion Inhibitors; HIV Infections; HIV-1; Humans; Mutation; Peptide Fragments; Salvage Therapy; Treatment Failure; Viremia

Topics: Acquired Immunodeficiency Syndrome; Amino Acid Substitution; Anti-HIV Agents; CD4-Positive T-Lymphocytes; Enfuvirtide; Evolution, Molecular; HIV Envelope Protein gp41; HIV-1; Humans; Peptide Fragments; Receptors, CCR5; Sequence Analysis, DNA; Viremia