Efficacy of raltegravir switching strategies in HIV-infected patients with suppressed viraemia according to the genotypic sensitivity score.

BACKGROUND AND PURPOSE: The lack of antiretroviral (ARV) backbone activity associated with raltegravir has been proposed as the main explanation for virological relapse observed in patients with undetectable viraemia who are switched from a ritonavir-boosted protease inhibitor (PI) to raltegravir. However ARV activity remains difficult to assess in this context. The aim of our study was to precisely assess the ARV backbone activity in patients with undetectable viraemia who underwent raltegravir switching strategies and to evaluate the efficacy of such switching strategies based on the genotypic sensitivity score (GSS). METHODS: Patients with a plasma human immunodeficiency virus type 1 (HIV-1) RNA level of <50 copies/mL on a stable two ARV-class regimen were enrolled if they switched one of their ARV drugs to raltegravir 400 mg twice daily. The GSS was calculated using a genotyping test performed on the HIV-1 RNA of the last plasma measurement with a HIV-1 RNA level of >50 copies/mL before the switch and on the results of all previous genotyping tests. The primary endpoint was the proportion of patients with a plasma HIV-1 RNA level of <50 copies/mL at week 24. RESULTS: Fifty-six patients were enrolled in this study. The proportion of patients with a plasma HIV-1 RNA level of <50 copies/mL at week 24 was 92.9 % (range 83.0-97.2 %) in the intent-to-treat analysis and 98.1 % (90.0-99.7 %) in per-protocol analysis. When the backbone was fully active, the proportion was 100.0 % (86.7-100.0 %) at week 24 and week 48 in the per-protocol analysis. We observed a decrease in plasma total cholesterol and triglycerides of -12.7 % (p = 0.005) and -26.5 % (p = 0.001), respectively. CONCLUSIONS: Raltegravir switching strategies are effective when the associated backbone is fully active according to the GSS. In the context of undetectable viraemia, where ARV activity remains difficult to assess, the determination of the GSS requires the entire ARV history of the patient and all previous HIV-RNA genotyping test results.

A mathematical model for mechanotransduction at the early steps of suture formation.

Growth and patterning of craniofacial sutures is subjected to the effects of mechanical stress. Mechanotransduction processes occurring at the margins of the sutures are not precisely understood. Here, we propose a simple theoretical model based on the orientation of collagen fibres within the suture in response to local stress. We demonstrate that fibre alignment generates an instability leading to the emergence of interdigitations. We confirm the appearance of this instability both analytically and numerically. To support our model, we use histology and synchrotron X-ray microtomography and reveal the fine structure of fibres within the sutural mesenchyme and their insertion into the bone. Furthermore, using a mouse model with impaired mechanotransduction, we show that the architecture of sutures is disturbed when forces are not interpreted properly. Finally, by studying the structure of sutures in the mouse, the rat, an actinopterygian (Polypterus bichir) and a placoderm (Compagopiscis croucheri), we show that bone deposition patterns during dermal bone growth are conserved within jawed vertebrates. In total, these results support the role of mechanical constraints in the growth and patterning of craniofacial sutures, a process that was probably effective at the emergence of gnathostomes, and provide new directions for the understanding of normal and pathological suture fusion.

Resistance profiles of emtricitabine and lamivudine in tenofovir-containing regimens.

OBJECTIVES: To compare the frequency of the selection of the M184V/I resistance mutation in HIV-infected patients who experienced virological failure while receiving emtricitabine (FTC) or lamivudine (3TC), administered with tenofovir disoproxil fumarate (TDF) and either efavirenz (EFV) or a ritonavir-boosted protease inhibitor (PI; lopinavir or atazanavir). METHODS: Patient data held at two clinical centres in France were analysed retrospectively. Eligible patients had experienced virological suppression (plasma HIV RNA <200 copies/mL) for ≥ 6 months before experiencing their first virological failure (at least two measurements of plasma HIV RNA ≥ 200 copies/mL). RESULTS: Of the 880 patients eligible for the study, 278 patients had experienced virological failure while receiving FTC + TDF + ritonavir-boosted PI, 257 while receiving FTC + TDF + EFV, 178 while receiving 3TC + TDF + EFV and 167 while receiving 3TC + TDF + ritonavir-boosted PI. Proportions of patients harbouring the M184V/I mutation were 24% (n = 62) for those who received FTC + TDF + EFV versus 51% (n = 91) for 3TC + TDF + EFV (P < 0.0001; Fisher's exact test); proportions were 11% (n = 30) for FTC + TDF + ritonavir-boosted PI versus 22% (n = 37) for 3TC + TDF + ritonavir-boosted PI (P = 0.002; Fisher's exact test). The use of lamivudine versus emtricitabine (P = 0.001), non-nucleoside reverse transcriptase inhibitors versus ritonavir-boosted PIs (P = 0.01) and the level of viral load at the time of virological failure (P = 0.01) were associated with selection of the M184V/I mutation (logistic regression analysis). CONCLUSIONS: Emtricitabine and lamivudine showed differing resistance profiles when administered in combination with tenofovir disproxil fumarate and either efavirenz or a ritonavir-boosted PI. The prevalence of the M184V/I resistance mutation was significantly lower in patients who received emtricitabine and tenofovir disoproxil fumarate than in those who received lamivudine and tenofovir disoproxil fumarate.

The use of human immunodeficiency virus resistance tests in clinical practice.

Important progress has been made in recent years in the development and clinical use of drugs for the treatment of human immunodeficiency virus type 1 (HIV-1) infection. Nevertheless, when antiretroviral therapy fails to be fully suppressive, new viral variants emerge, thus allowing HIV-1 to escape from drug pressure by accumulating mutations. Between 50% and 70% of treated patients with virological rebound harbour some form of drug-resistant virus; transmitted drug resistance in drug-naïve populations has reached 5-20% in areas of the world with access to treatment. The emergence of drug-resistant viruses remains the limiting factor in HIV-1 management, being a major cause of treatment failure, and being associated with clinical progression and death. All international guidelines focus on the importance of tailoring antiretroviral therapy to the individual patient, on the basis onf HIV-1 genetic data, integrated with clinical, laboratory and therapeutic information. The aim of this review is to provide useful information to clinicians and virologists about how and when to use genotypic resistance testing in clinical practice, especially in the management of the first stages of HIV-1 patient care and treatment decisions.

[HIV tropism assays when first CCR5-antagonist becomes available]. / Les tests de tropisme du VIH à l'heure de la mise à disposition du 1(er) anti-CCR5.

Since its co-receptors were discovered, HIV tropism is defined by the type of co-receptor used to infect its host cells : R5 for viruses using only CCR5, X4 for viruses using only CXCR4, and R5/X4 or dual for viruses using either CCR5 or CXCR4. Tropism prediction actually made is via recombinant phenotypic assays, which are labour-intensive, long-lasting and expensive, available in only a few highly qualified laboratories. Prescription of CCR5-antagonists requires screening for the presence of X4 variants before starting therapy. With development of this new class of antiretrovirals there is a need for genotypic tests, based on V3 loop gp 120 env gene sequencing and its interpretation with an algorithm. As for resistance tests 10 years ago, these genotypic tests will be easier to introduce into routine clinical practice. These genotypic tropism assays will help to select patients before CCR5-antagonist prescription and to follow patients treated by this class of antiretrovirals, looking for a potential switch of tropism during therapy.

KSHV after an organ transplant: should we screen?

The incidence of Kaposi sarcoma (KS) related to Kaposi sarcoma-associated herpesvirus (KSHV/HHV-8) after organ transplantation is 500-1000 times greater than in the general population, and its occurrence is associated with immunosuppressive therapy. The reported incidence of posttransplant KS ranges from 0.5% to 5%, depending on the patient's country of origin and the type of organ received, mainly after renal transplantation. Posttransplant KS is caused by two possible mechanisms: KSHV reactivation in patients who were infected before the graft and KSHV contamination from the infected organ's donor to the recipient. KSHV reactivation appears to play a greater role in the risk of KS than incident infections. However, some studies, with findings based not only on serological data but also on molecular tracing of the viral infection, have shown that organ-related transmission of KSHV could be more common than previously thought and associated in some cases with severe KSHV-related disease. Precise estimates of KSHV seroprevalence in the organ donor and recipient populations in different countries are lacking. However, studies have reported seroprevalences among donors and recipients that are similar to those among the general population of the country considered. Many studies have suggested the potential utility of screening of KSHV antibodies among organ donors and recipients. However, to date the results of these studies have argued in favor of KSHV screening, even in low-KSHV infection prevalence countries, not to exclude the graft but to have the KSHV status information in order to have the opportunity to monitor, clinically and biologically, patients at risk for KSHV-related disease development. The detection of KSHV antibodies could be done in the days after the transplantation and the results transmitted to the physicians retrospectively. In conclusion, the question of screening donors and recipients for KSHV, even in low-KSHV infection prevalence countries, is still debated, and prospective studies are needed to evaluate the benefit of pre- and posttransplantation strategies.

Persistent low viral load on antiretroviral therapy is associated with T cell-mediated control of HIV replication.

BACKGROUND: It is unclear how stable low-level viral replication and CD4 cell numbers can be maintained under highly active antiretroviral therapy (HAART). This study was designed to analyse whether HIV-specific responses in stable partially controlled patients during antiretroviral therapy (ART) differ from those observed in complete HAART failure and whether they contribute to the control of viral load (VL). METHODS: Three groups of patients were selected according to plasma HIV RNA levels during 18 months of ART: persistently low VL (LoVL; HIV RNA <10,000 copies/ml; n = 28), undetectable VL (UnVL; HIV RNA <200 copies/ml; n = 29) and high VL (HiVL; HIV RNA >10,000 copies/ml; n = 14). T-cell responses were studied using lymphoproliferative and interferon (IFN)-gamma-ELISpot assays against HIV-p24, -gp160, recall antigens, and 15 pools of HIV-(Gag + RT) peptides. RESULTS: Frequencies of IFN-gamma-producing CD4 T cells against HIV-p24 were higher in LoVL than in UnVL or HiVL groups [median, 131, 47 and 23 spot-forming cells (SFC)/1 x 10 peripheral blood mononuclear cells (PBMC), respectively; P = 0.012 and P = 0.047]. Lymphoproliferative responses to HIV-p24 and recall antigens were similar in LoVL and UnVL groups but lower in HiVL (P = 0.004). Frequencies of HIV-specific CD8 T cells were higher in LoVL than in UnVL (1340 versus 410 SFC/1 x 10 PBMC; P = 0.001). They correlated negatively with VL in the LoVL and HiVL (r, -0.393, P = 0.039 and r, -0.643, P = 0.024, respectively) and positively correlated with anti-HIV CD4 cell frequencies in the LoVL group only (r, 0.420; P = 0.026). CONCLUSION: Persistently low viral replication (<10,000 copies/ml) during ART stimulates high frequencies of HIV-specific CD4 and CD8 T cells compared to full virus suppression or complete ART failure. The association of high anti-HIV activity with large numbers of HIV-specific CD8 T cells contribute to the control of viral replication.

[Therapeutic strategies for HIV infection: virology approach]. / Approche virologique.

Among antiretroviral therapies available for the treatment of human immunodeficiency virus infection, protease inhibitors (PI) are the most promising molecules. Yet they are likely to induce the emergence of resistance mutations in viral strains, which as a consequence can affect their efficacy. Boosting has improved PI's efficacy by increasing their half-life and trough concentration. Boosted PI are hence, especially relevant for the treatment of patients with virological failure. Moreover, using boosted PI as first line treatment could avoid the appearance of viral mutations in case of virological failure. Indeed, boosted PI are more rapidly cleared from blood circulation than unboosted PI. Their concentrations rapidly drop and cross the range of sub-inhibitory drug concentrations i.e. the zone of highest selective pressure, thus limiting the risk of viral mutations.

P-glycoprotein in blood CD4 cells of HIV-1-infected patients treated with protease inhibitors.

OBJECTIVE: Many factors are involved in the virological failure of antiretroviral treatments such as low pharmacological plasma levels of drugs, poor adherence to therapy and emergence of viral resistance. P-glycoprotein (P-gp) has been demonstrated to play a role in multidrug resistance in the therapy of solid tumours, haematological malignancies and Plasmodium falciparum infection. HIV-1 protease inhibitors (PIs) have been described to be substrates of P-gp. In vitro and in vivo studies performed in mice have demonstrated that P-gp may affect the oral bioavailability and intracellular accumulation of PIs. P-gps have been detected on peripheral CD4 blood cells in HIV-1-infected, but antiretroviral-naive patients. METHOD: We quantified P-gp expression and performed functional tests of P-gp activity in the CD4 cells in HIV-1-infected patients, with and without virological failure, treated with PIs, and in healthy patients (control group). RESULT: Out of the 18 HIV-infected patients studied, P-gp expression and function were found in the CD4 cells of six patients (four of 10 without, and two of eight with virological failure). Out of the 43 healthy patients studied, P-gp expression and function were found in the CD4 cells of 11 patients (26%). We found P-gp in peripheral CD4 cells of patients treated with PIs, with and without virological failure, within the same frequency than in antiretroviral naive patients or than in non HIV-infected patients. CONCLUSIONS: P-gp expression in peripheral CD4 blood cells does not seem to be enhanced by PI treatment and does not seem to be linked particularly to virological failures. These facts do not preclude of the role of P-gp on PI absorption or efficacy in other compartments of the body such as gut, lymph nodes or brain in HIV-1 PI-treated patients.

Effects of cyclosporine and hydrocortisone on Kaposi's sarcoma-associated herpesvirus genome replication and cell apoptosis induction.

BACKGROUND: Iatrogenic immunosuppressed patients are at increased risk for development of various cancers that comprise Kaposi's sarcoma (KS). METHODS: To investigate the direct impact of immunosuppressive agents on Kaposi's sarcoma-associated herpesvirus (KSHV) and KS development, we quantified the effects of cyclosporine (CsA) and hydrocortisone (HC) on KSHV genome replication and the consequences on the cell survival. RESULTS: In the presence of phorbol ester 12-O-tetradecanoyl phorbol-13-acetate, we observed an increase of intracellular and extracellular KSHV DNA concomitantly with an increase of gp (glycoprotein) K8.1 expression, indicating KSHV genome replication. This replication was accompanied by cell apoptosis. In comparison, in the presence of CsA, HC, or both, we did not observe any effect on KSHV replication or gp K8.1 expression. CONCLUSION: Our results suggest that immunosuppressive agents such as HC and CsA do not activate the lytic cycle of KSHV and do not modify the cell survival thus promoting cancer progression by a direct cellular effect.

Human herpesvirus-8 seroconversions after renal transplantation.

BACKGROUND: Human herpesvirus-8 (HHV-8) is a new human herpesvirus that is clearly associated with Kaposi's sarcoma (KS). A previous study has reported that the prevalence of KS in a cohort of renal transplant recipients with previous HHV-8 infection was 28% and two other studies have shown that KS can be linked to HHV-8 seroconversion after graft. The aim of this study was to evaluate the HHV-8 seroconversion rate in a cohort of renal allograft recipients in Paris. METHODS: Two hundred eighty-seven patients who were HHV-8 seronegative before renal transplantation were tested for HHV-8 antibodies by an immunofluorescence assay 12 months after transplantation. RESULTS: Of the 287 patients, 6 (2.09%) seroconverted after renal transplantation. None of these 6 patients developed KS within 3 years of the first HHV-8 positive serum. None of the clinical manifestations that could be associated with HHV-8 primary infection were observed during the seroconversion. CONCLUSIONS: Our results demonstrated that HHV-8 seroconversion can be observed even in a low HHV-8 prevalence area and confirmed the need to perform systematic screening for HHV-8 antibodies in renal graft donors and recipients.

Efficacy of dideoxynucleosides against human foamy virus and relationship to its reverse transcriptase amino acid sequence and structure.

Human foamy virus (HFV), a retrovirus of simian origin which occasionally infects humans, is the basis of retroviral vectors in development for gene therapy. Clinical considerations of how to treat patients developing an uncontrolled infection by either HFV or HFV-based vectors need to be raised. We determined the susceptibility of the HFV to dideoxynucleosides and found that only zidovudine was equally efficient against the replication of human immunodeficiency virus type 1 (HIV-1) and HFV. By contrast, zalcitabine (ddC), lamivudine (3TC), stavudine (d4T), and didanosine (ddI) were 3-, 3-, 30-, and 46-fold less efficient against HFV than against HIV-1, respectively. Some amino acid residues known to be involved in HIV-1 resistance to ddC, 3TC, d4T, and ddI were found at homologous positions of HFV reverse transcriptase (RT). These critical amino acids are located at the same positions in the three-dimensional structure of HIV-1 and HFV RT, suggesting that both enzymes share common patterns of inhibition.

[Management of therapeutic failure in HIV-infected patients]. / Gestion des échappements thérapeutiques des patients infectés par le VIH.

A COMMON SITUATION: Among HIV-infected patients treated with antiretroviral regimens, 20% to 50% escape therapeutic control. The principal factors predictive of treatment failure are low CD4 counts and high viral load prior to institution of the antiretroviral treatment. Several virological and pharmacological mechanisms are implicated. GENOTYPING AND PHENOTYPING: Genotyping is particularly useful to optimize treatment in HIV-infected patients who escape therapeutic control, irrespective of the therapeutic strategy. A committee of experts has developed a scheme for adapting treatment to the very complex results of genotyping tests. The benefit of phenotyping remains to be established. MANAGEMENT: Serum concentrations of antiretroviral agents should be determined and adapted in order to maximize the treatment effect. However, to manage therapeutic escape, the only method with a proven impact is genotyping. The possible usefulness of regular drug assays for adjusting treatment doses in case of therapeutic escape remains to be assessed in prospective trials.

Clinical features and contribution of virological findings to the management of Kaposi sarcoma in organ-allograft recipients.

OBJECTIVES: To describe the clinical features of Kaposi sarcoma (KS) in organ-allograft recipients and to determine the contribution of human herpesvirus 8 (HHV-8) investigations to the management of KS. DESIGN, SETTING, AND PATIENTS: We examined 20 organ-allograft recipients with KS at Pitié-Salpêtrière Hospital, Paris, France, between November 1, 1991, and May 31, 1999. METHODS: We detected HHV-8 antibodies using an indirect immunofluorescence assay and the HHV-8 DNA genome using nonnested polymerase chain reaction with KS-associated herpesvirus 330(233) primers in peripheral blood mononuclear cells collected at transplantation and KS diagnosis. We detected the HHV-8 genome in involved and uninvolved tissue specimens and in 10 patients' serum samples collected 1 month before the first manifestation of KS. We determined the HHV-8 double-strand DNA sequence and subtypes of open reading frame 26. INTERVENTION: Management of KS consisted of progressively tapering immunosuppressive therapy regardless of KS dissemination. Associated infections were treated when possible. Chemotherapy was prescribed only when a functional disability persisted, and polychemotherapy was prescribed for life-threatening disease. MAIN OUTCOME MEASURES: Percentage of recipients with KS remission and stabilization, organ-graft survival, and death rates. RESULTS: Remission of KS was obtained in 9 (45%) of the 20 patients independently of disease dissemination, with a mean follow-up of 35 months. The kidney graft survived in 12 (67%) of the 18 patients. Only 1 patient (5%) died of KS progression. All allograft recipients had anti-HHV-8 antibodies before transplantation. We detected HHV-8 DNA in all involved tissue samples but not in serum samples 1 month before KS onset. The most prevalent subtype was HHV-8 C (9 [53%] of 17 patients) and was not associated with extradermatological extension of KS compared with subtypes A and B'. CONCLUSIONS: Virological investigations of HHV-8 contribute poorly to KS management. Prospective studies are needed to determine the role of HHV-8 virological investigations and to identify associated cofactors so as to prevent KS in organ-allograft recipients.

Immunogenicity of mutations induced by nucleoside reverse transcriptase inhibitors for human immunodeficiency virus type 1-specific cytotoxic T cells.

The impact of drug resistance mutations induced by nucleoside reverse transcriptase (RT) inhibitors (NRTI) on cytotoxic T-lymphocyte (CTL) recognition of human immunodeficiency virus type 1 strain LAI (HIV-1(LAI)) RT was addressed in 35 treated or untreated patients. Two HIV-1(LAI) RT regions encompassing mutation M41L, L74V, M184V, and T215Y/F were recognized in 75 and 83% mutated and in 33 and 42% unmutated samples, respectively. A total of 41 new CTL epitopes overlapping these mutations were predicted. Mutations enhanced HLA-binding scores of 17 epitopes, decreased scores of 5, and had no effect in 19. Four predicted epitopes containing mutations 41, 74, and 184 were tested and recognized by CD8 cells from mutated or unmutated samples, with frequencies up to 270 gamma interferon spot-forming cells per 10(6) peripheral blood mononuclear cells. Therefore, RT mutations induced by NRTI can increase the immunogenicity of RT for CTL and might allow a better immune control of resistant viruses in vivo, suggesting that specific immune therapy might help prevent these mutations.

Dynamics of HIV-specific CD8+ T lymphocytes with changes in viral load.The RESTIM and COMET Study Groups.

The influence of HIV burden variations on the frequencies of Ag-specific CD8+ T cell responses was evaluated before and during highly active antiretroviral therapy by analyzing the number, diversity, and function of these cells. The frequencies of HLA-A2-restricted CD8+ PBL binding HLA-A2/HIV-epitope tetramers or producing IFN-gamma were below 1%. A panel of 16 CTL epitopes covering 15 HLA class I molecules in 14 patients allowed us to test 3.8 epitopes/patient and to detect 2.2 +/- 1.8 HIV epitope-specific CD8+ subsets per patient with a median frequency of 0.24% (0.11-4. 79%). During the first month of treatment, viral load rapidly decreased and frequencies of HIV-specific CD8 PBL tripled, eight new HIV specificities appeared of 11 undetectable at entry, while CMV-specific CD8+ PBL also appeared. With efficient HIV load control, all HIV specificities decayed involving a reduction of the CD8+CD27+CD11ahigh HIV-specific effector subset. Virus rebounds triggered by scheduled drug interruptions or transient therapeutic failures induced four patterns of epitope-specific CD8+ lymphocyte dynamics, i.e., peaks or disappearance of preexisting specificities, emergence of new specificities, or lack of changes. The HIV load rebounds mobilized both effector/memory HIV- and CMV-specific CD8+ lymphocytes. Therefore, frequencies of virus-specific CD8 T cells appear to be positively correlated to HIV production in most cases during highly active antiretroviral therapy, but an inverse correlation can also be observed with rapid virus changes that might involve redistribution, sequestration, or expansion of these Ag-specific CD8 T cells. Future strategies of therapeutic interruptions should take into account these various HIV-specific cell dynamics during HIV rebounds.