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Guido Vanham

Publications and source records attributed to Guido Vanham.

At least 19 recordsLinked to original sources
PubMed2007

Is HIV-1 evolving to a less virulent form in humans?

During the rapid spread of HIV-1 in humans, the main (M) group of HIV-1 has evolved into ten distinct subtypes, undergone countless recombination events and diversified extensively. The impact of this extreme genetic diversity on the phenotype of HIV-1 has only recently become a research focus, but early findings indicate that the dominance of HIV-1 subtype C in the current epidemic might be related to the lower virulence of this subtype compared with other subtypes. Here, we explore whether HIV-1 has reached peak virulence or has already started the slow path to attenuation.

Animals↗
PubMed2006

A dual chamber model of female cervical mucosa for the study of HIV transmission and for the evaluation of candidate HIV microbicides.

A dual chamber system was established to model heterosexual HIV transmission. Cell-associated, but not cell-free HIV, added to a confluent layer of cervical epithelial cells in the apical chamber, reproducibly infected monocyte-derived dendritic cells (MO-DC) and CD4(+) T cells in the basal compartment. Only minimal epithelial transmigration of HIV-infected mononuclear cells (HIV-PBMCs) was observed. Most evidence points to transepithelial migration of virus, released from HIV-PBMCs after their activation by epithelial cells. We used this model for evaluation of the therapeutic index of various potentially preventive antiviral compounds, including non-nucleoside reverse transcriptase inhibitors (NNRTIs, including UC781 and various diaryltriazines and diarylpyrimidines), poly-anionic entry inhibitors (including PRO2000, cellulose sulphate, dextrane sulphate 5000 and polystyrene sulphonate) and the fusion inhibitor T-20. The epithelium was pre-treated with compound and incubated with HIV-PBMCs for 24 h. Afterwards the apical chamber was removed and MO-DC/CD4(+) T cell co-cultures were further cultured without compound. NNRTIs, including a TMC120 gel, blocked infection of the sub-epithelial targets at sub-micromolar concentrations. Polyanionic entry inhibitors (up to 100 microg/ml) and T-20 (up to 449 microg/ml) failed to inhibit transmission. Moreover, whereas the NNRTIs used interfered with epithelial integrity with cervical epithelium only at very high concentrations, the evaluated entry inhibitors showed toxicity at concentrations that did not prevent infection.

Anti-HIV Agents↗
PubMed2006

Carbohydrate-binding agents efficiently prevent dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN)-directed HIV-1 transmission to T lymphocytes.

Exposure of HIV-1 to dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN)-expressing B-lymphoblast Raji cells (Raji/DC-SIGN) but not to wild-type Raji/0 cells results in the capture of HIV-1 particles to the cells as measured by the quantification of cell-associated p24 antigen. Cocultivation of HIV-1-captured Raji/DC-SIGN cells with uninfected CD4+ T lymphocyte C8166 cells results in abundant formation of syncytia within 36 h after cocultivation. Short preexposure of HIV-1 to carbohydrate-binding agents (CBA) dose dependently prevents the Raji/DC-SIGN cells from efficiently binding the virus particles, and no syncytia formation occurs upon subsequent cocultivation with C8166 cells. Thus, the mannose-specific [i.e., the plant lectins Hippeastrum hybrid agglutinin (HHA), Galanthus nivalis agglutinin (GNA), Narcissus pseudonarcissus agglutinin; and Cymbidium agglutinin (CA); the procaryotic cyanovirin-N (CV-N); and the monoclonal antibody 2G12) and N-acetylglucosamine-specific (i.e., the plant lectin Urtica dioica agglutinin) CBAs efficiently abrogate the DC-SIGN-directed HIV-1 capture and subsequent transmission to T lymphocytes. In this assay, the CD4-down-regulating cyclotriazodisulfonamide derivative, the CXCR4 and CCR5 coreceptor antagonists 1-[[4-(1,4,8,11-tetrazacyclotetradec-1-ylmethyl)phenyl]methyl] - 1,4,8,11 - tetrazacyclotetradecane (AMD3100) and maraviroc, the gp41-binding enfuvirtide, and the polyanionic substances dextran sulfate (M(r) 5000), sulfated polyvinyl alcohol, and the naphthalene sulfonate polymer PRO-2000 were markedly less efficient or even completely ineffective. Similar observations were made in primary monocyte-derived dendritic cell cultures that were infected with HIV-1 particles that had been shortly pre-exposed to the CBAs CV-N, CA, HHA, and GNA and the polyanions DS-5000 and PRO-2000. The potential of CBAs, but not polyanions and other structural/functional classes of entry inhibitors, to impair DC-SIGN-expressing cells in their capacity of transmitting HIV to T lymphocytes might be an important property to be taken into consideration in the eventual choice to move microbicide candidate drugs to the clinical setting.

Anti-HIV Agents↗
PubMed2006

The predominance of Human Immunodeficiency Virus type 1 (HIV-1) circulating recombinant form 02 (CRF02_AG) in West Central Africa may be related to its replicative fitness.

BACKGROUND: CRF02_AG is the predominant HIV strain circulating in West and West Central Africa. The aim of this study was to test whether this predominance is associated with a higher in vitro replicative fitness relative to parental subtype A and G viruses. Primary HIV-1 isolates (10 CRF02_AG, 5 subtype A and 5 subtype G) were obtained from a well-described Cameroonian cohort. Growth competition experiments were carried out at equal multiplicity of infection in activated T cells and monocyte-derived dendritic cells (MO-DC) in parallel. RESULTS: Dual infection/competition experiments in activated T cells clearly indicated that CRF02_AG isolates had a significant replication advantage over the subtype A and subtype G viruses. The higher fitness of CRF02_AG was evident for isolates from patients with CD4+ T cell counts >200 cells/microL (non-AIDS) or CD4+ T cell counts <200 cells/microL (AIDS), and was independent of the co-receptor tropism. In MO-DC cultures, CRF02_AG isolates showed a slightly but not significantly higher replication advantage compared to subtype A or G isolates. CONCLUSION: We observed a higher ex vivo replicative fitness of CRF02_AG isolates compared to subtype A and G viruses from the same geographic region and showed that this was independent of the co-receptor tropism and irrespective of high or low CD4+ T cell count. This advantage in replicative fitness may contribute to the dominant spread of CRF02_AG over A and G subtypes in West and West Central Africa.

CD4-Positive T-Lymphocytes↗
PubMed2006

SYBR Green-based quantitation of human T-lymphotropic virus type 1 proviral load in Peruvian patients with neurological disease and asymptomatic carriers: influence of clinical status, sex, and familial relatedness.

To evaluate the human T-lymphotropic virus type 1 (HTLV-1) proviral DNA load in patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and asymptomatic HTLV-1 carriers, a SYBR Green-based real-time quantitative polymerase chain reaction (qPCR) assay was developed. HTLV-1 proviral DNA in peripheral blood mononuclear cells (PBMCs) was quantified using primers targeting the pX region and the HTLV-1 copy number normalized to the amount of ERV-3 (Endogenous Retrovirus 3) cellular DNA. Thirty-three asymptomatic HTLV-1 carriers (ACs) and 39 patients with HAM/TSP were enrolled. Some participants were relatives of HAM/TSP cases (16 ACs and 7 patients with HAM/TSP). On multiple linear regression analysis, the authors found a significant association between clinical status and HTLV-1 proviral load (P < .01), but only among women. ACs showed a median proviral load of 561 copies per 104 PBMCs (interquartile range: 251-1623). In HAM/TSP patients, the median proviral load was 1783 (1385-2914). ACs related to HAM/TSP patients presented a relatively high proviral load (median 1152); however, the association between relatedness to a HAM/TSP patient and proviral load was not significant (P = .1). In HAM/TSP patients, no association was found between proviral load and disease duration, progression or severity. The fact that the effect of HAM/TSP upon the HTLV-1 proviral load differed between sexes and the finding of a high proviral load among asymptomatic relatives of HAM/TSP patients suggest that not yet identified genetic or environmental factors influence the pathogenesis of HTLV-1 infection.

Benzothiazoles↗
PubMed2005

Replicative fitness of CCR5-using and CXCR4-using human immunodeficiency virus type 1 biological clones.

CCR5-tropic viruses cause the vast majority of new HIV-1 infections while about half of the individuals infected with HIV-1 manifest a co-receptor switch (CCR5 (R5) to CXCR4 (X4)) prior to accelerated disease progression. The underlying biological mechanisms of X4 outgrowth in AIDS patients are still poorly understood. Although X4 viruses have been associated with increased "virulence" in vivo, in vitro replication and cytopathicity studies of X4 and R5 viruses have led to conflicting conclusions. We studied the replicative fitness of HIV-1 biological clones with different co-receptor tropism, isolated from four AIDS patients. On average, R5 and X4 clones replicated equally well in mitogen-activated T cells. In contrast, X4 variants were transferred more efficiently from dendritic cells to autologous CD4+ T cells. These observations suggest that interaction between X4 viruses, DC and T cells might contribute to the preferential outgrowth of X4 viruses in AIDS patients.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Efficient stimulation of HIV-1-specific T cells using dendritic cells electroporated with mRNA encoding autologous HIV-1 Gag and Env proteins.

Infection with human immunodeficiency virus type 1 (HIV-1) is characterized by dysfunction of HIV-1-specific T cells. To control the virus, antigen-loaded dendritic cells (DCs) might be useful to boost and broaden HIV-specific T-cell responses. In the present study, monocyte-derived DCs from nontreated HIV-1-seropositive patients were electroporated with codon-optimized ("humanized") mRNA encoding consensus HxB-2 (hHXB-2) Gag protein. These DCs elicited a strong HIV-1 Gag-specific interferon-gamma (IFN-gamma) response by an HLA-A2-restricted CD8+ T-cell line. Moreover, hHXB-2 gag mRNA-electroporated DCs also triggered IFN-gamma secretion by autologous peripheral blood mononuclear cells (PBMCs), CD4+ T cells, and CD8+ T cells from all patients tested. Next, a novel strategy was developed using autologous virus sequences. Significant specific IFN-gamma T-cell responses were induced in all patients tested by DCs electroporated with patients' autologous polymerase chain reaction (PCR)-amplified and in vitro-transcribed proviral and plasma viral mRNA encoding either Gag or Env. The stimulatory effect was seen on PBMCs, CD8+ T cells, and CD4+ T cells, demonstrating both major histocompatibility complex (MHC) class I and MHC class II antigen presentation. Moreover, a significant interleukin-2 (IL-2) T-cell response was induced by DCs electroporated with hHxB-2 or proviral gag mRNA. These findings open a major perspective for the development of patient-specific immunotherapy for HIV-1 disease.

Adoptive Transfer↗
PubMed2005

Replicative fitness of historical and recent HIV-1 isolates suggests HIV-1 attenuation over time.

BACKGROUND: Changes in virulence during an epidemic are common among pathogens, but still unexplored in the case of HIV-1. Here we used primary human cells to study the replicative fitness of primary HIV-1 isolates from untreated patients, comparing historical (1986-1989) and recent samples (2002-2003). METHODS: Head-to-head dual virus infection/competition assays were performed in both peripheral blood mononuclear cells and human dendritic cell/T-cell co-cultures with pairs of 12 carefully matched historical and recent HIV-1 isolates from untreated patients. Sensitivity to inhibition by lamivudine (3TC) and TAK-779 of historical and recent R5 HIV-1 isolates was measured in a subset of samples. RESULTS: Overall, the historical HIV-1 out-competed the recent HIV-1 isolates in 176 of 238 competitions and in 9 of 12 competitions carefully matched for CD4 cell count. The mean relative replicative fitness (W) of all historical HIV-1 strains was significantly greater than that of recent HIV-1 isolates (W(1986-1989) = 1.395 and W(2002-2003) = 0.545, P < 0.001 (t test)). The more fit viruses (mean W > 1) from 1986-1989 appeared less sensitive to TAK-779 and 3TC than did the less fit (mean W < 1) 2002-2003 viruses. CONCLUSIONS: These findings suggest that HIV-1 replicative fitness may have decreased in the human population since the start of the pandemic. This 'attenuation' could be the consequence of serial bottlenecks during transmission and result in adaptation of HIV-1 to the human host.

Amides↗
PubMed2005

The replicative fitness of primary human immunodeficiency virus type 1 (HIV-1) group M, HIV-1 group O, and HIV-2 isolates.

The main (M) group of human immunodeficiency virus type 1 (HIV-1) is responsible for the global AIDS epidemic while HIV-1 group O (outlier) and HIV type 2 are endemic only in west and central Africa. The failure of HIV-2 and especially HIV-1 group O to spread following the initial zoonotic jumps is not well understood. This study was designed to examine the relative replicative capacities between these human lentiviruses. A pairwise competition experiment was performed with peripheral blood mononuclear cells with eight HIV-2 isolates, 6 group O viruses, and 15 group M viruses of subtype A (2 viruses), B (5 viruses), C (4 viruses), D (2 viruses) and CRF01_AE (2 viruses). HIV-1 group M isolates of any subtype were typically 100-fold-more fit than group O or HIV-2 strains when competed in peripheral blood mononuclear cells from various humans. This order in replicative fitness was also observed when virus pairs were added to human dendritic cells and then cocultured with primary, quiescent T cells, which is the model for HIV-1 transmission. These results suggest that reduced replicative and transmission fitness may be contributing to the low prevalence and limited geographical spread of HIV-2 and group O HIV-1 in the human population.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Changes in human immunodeficiency virus type 1 fitness and genetic diversity during disease progression.

This study examined the relationship between ex vivo human immunodeficiency virus type 1 (HIV-1) fitness and viral genetic diversity during the course of HIV-1 disease. Primary HIV-1 isolates from 10 patients at different time points were competed against control HIV-1 strains in peripheral blood mononuclear cell (PBMC) cultures to determine relative fitness values. Patient HIV-1 isolates sequentially gained fitness during disease at a significant rate that directly correlated with viral load and HIV-1 env C2V3 diversity. A loss in both fitness and viral diversity was observed upon the initiation of antiretroviral therapy. A possible relationship between genotype and phenotype (virus replication efficiency) is supported by the parallel increases in ex vivo fitness and viral diversity during disease, of which the correlation is largely based on specific V3 sequences. Syncytium-inducing, CXCR4-tropic HIV-1 isolates did have higher relative fitness values than non-syncytium-inducing, CCR5-tropic HIV-1 isolates, as determined by dual virus competitions in PBMC, but increases in fitness during disease were not solely powered by a gradual switch in coreceptor usage. These data provide in vivo evidence that increasing HIV-1 replication efficiency may be related to a concomitant increase in HIV-1 diversity, which in turn may be a determining factor in disease progression.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Pre-incubation of cell-free HIV-1 group M isolates with non-nucleoside reverse transcriptase inhibitors blocks subsequent viral replication in co-cultures of dendritic cells and T cells.

In order to study the inhibitory effect of various reverse transcriptase inhibitors (RTIs) on cell-free HIV, we adapted a recently described in vitro system, based on co-cultures of dendritic cells and resting CD4 T cells, modelling early target cells during sexual transmission. The compounds tested included the second-generation non-nucleoside RTI (NNRTI) TMC-120 (R147681, dapivirine) and TMC-125 (R165335, travertine), as well as the reference nucleoside RTI AZT (zidovudine), the nucleotide RTI PMPA (tenofovir) and the NNRTI UC-781. The virus strains included the reference strain HIV-1Ba-L and six primary isolates, representative of the HIV-1 group M pandemic. They all display the non-syncytium-inducing and CCR5 receptor-using (NSI/R5) phenotype, important in transmission. Cell-free virus was immobilized on a poly-L-lysine (PLL)-treated microwell plate and incubated with compound for 1 h. Afterwards, the compound was thoroughly washed away; target cells were added and cultured for 2 weeks, followed by an extended culture with highly susceptible mitogen-activated T cells. Viral production in the cultures was measured on supernatant with HIV antigen ELISA. Negative results were confirmed by showing absence of proviral DNA in the cells. TMC-120 and TMC-125 inhibited replication of HIV-1Ba-L with average EC50 values of 38 nM and 117 nM, respectively, whereas the EC50 of UC-781 was 517 nM. Complete suppression of virus and provirus was observed at compound concentrations of 100, 300 and 1000 nM, respectively. Inhibition of all primary isolates followed the same pattern as HIV-1Ba-L. In contrast, pre-treating the virus with the nucleotide RTI PMPA and AZT failed to inhibit infection even at a concentration of 100000 nM. These data clearly suggest that NNRTIs inactivate RT enzymatic activity of different viral clades (predominant in the epidemic) and might be proposed for further testing as a sterilizing microbicide worldwide.

CD4-Positive T-Lymphocytes↗
PubMed2004

Macrophage galactose-type C-type lectins as novel markers for alternatively activated macrophages elicited by parasitic infections and allergic airway inflammation.

Molecular markers, especially surface markers associated with type II, cytokine-dependent, alternatively activated macrophages (aaMF), remain scarce. Besides the earlier documented markers, macrophage mannose receptor and arginase 1, we demonstrated recently that murine aaMF are characterized by increased expression of found in inflammatory zone 1 (FIZZ1) and the secretory lectin Ym. We now document that expression of the two members of the mouse macrophage galactose-type C-type lectin gene family (mMGL1 and mMGL2) is induced in diverse populations of aaMF, including peritoneal macrophages elicited during infection with the protozoan Trypanosoma brucei brucei or the Helminth Taenia crassiceps and alveolar macrophages elicited in a mouse model of allergic asthma. In addition, we demonstrate that in vitro, interleukin-4 (IL-4) and IL-13 up-regulate mMGL1 and mMGL2 expression and that in vivo, induction of mMGL1 and mMGL2 is dependent on IL-4 receptor signaling. Moreover, we show that expression of MGL on human monocytes is also up-regulated by IL-4. Hence, macrophage galactose-type C-type lectins represent novel surface markers for murine and human aaMF.

Animals↗
PubMed2004

Neutralization of primary HIV-1 SF13 can be detected in extended incubation phase assays with sera from monkeys immunized with recombinant HIV-1 SF2 gp120.

Phase III efficacy trials of recombinant human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins were postponed. In Phase I and II trials these candidate vaccines had failed to induce neutralizing antibodies against virus which had been isolated by co-culture with human peripheral blood mononuclear cells (PBMC). The aim of the present study was to determine assay conditions for detecting neutralization of primary HIV-1 isolates with sera from immunized individuals. We show that in two immunogenicity trials in rhesus macaques, recombinant HIV-1 SF2 gp120 induced antibodies which neutralized the primary HIV-1 SF13 isolate. Statistically significant in vitro neutralization required assays in which the incubation phase was extended. Sterile immunity was only seen with the highest level of neutralization, induced by a recombinant prime, peptide boost strategy. We recommend that neutralization assays with extended incubation phases should be used to monitor Phase III efficacy trials.

AIDS Vaccines↗
PubMed2004

In vitro evaluation of nonnucleoside reverse transcriptase inhibitors UC-781 and TMC120-R147681 as human immunodeficiency virus microbicides.

The nonnucleoside reverse transcriptase inhibitors UC-781 and TMC120-R147681 (Dapivirine) effectively prevented human immunodeficiency virus (HIV) infection in cocultures of monocyte-derived dendritic cells and T cells, representing primary targets in sexual transmission. Both drugs had a favorable therapeutic index. A 24-h treatment with 1,000 nM UC-781 or 100 nM TMC120-R147681 prevented cell-free HIV infection, whereas 10-fold-higher concentrations blocked cell-associated HIV.

Anilides↗
PubMed2004

A series of diaryltriazines and diarylpyrimidines are highly potent nonnucleoside reverse transcriptase inhibitors with possible applications as microbicides.

An in vitro model of monocyte-derived dendritic cells (MO-DC) and CD4(+) T cells, representing the primary targets of sexual human immunodeficiency virus (HIV) transmission, was used to evaluate the antiviral and immune suppressive activity of new classes of nonnucleoside reverse transcriptase inhibitors, diaryltriazines (DATAs) and diarylpyrimidines (DAPYs), compared to the reference compounds UC-781 and PMPA. Antiviral activity (as reflected by the 50% effective concentration [EC(50)]) was determined by treating HIV-infected MO-DC/CD4(+)-T-cell cocultures with a dose range of a compound during 14 days, followed by analysis of supernatants in HIV p24 antigen enzyme-linked immunosorbent assay. A limited, 24-h treatment evaluated the compounds as microbicides. Viral rescue was evaluated in a PCR by monitoring proviral DNA in secondary cultures with phytohemagglutinin-interleukin-2 blasts. We determined 50% immunosuppressive concentrations in mixed leukocyte cultures of MO-DC and allogeneic T cells, with compound either continuously present or present only during the first 24 h. The EC(50) values of DATA and DAPY compounds ranged from 0.05 to 3 nM compared to 50 nM for UC-781 and 89 nM for PMPA. When evaluated in the "microbicide" setting, the most potent compounds completely blocked HIV infection at 10 to 100 nM. The immunosuppressive concentrations were well above the EC(50), resulting in favorable therapeutic indices for all compounds tested. The DATA and DAPY compounds described here are more potent than earlier reverse transcriptase inhibitors and show favorable pharmacological profiles in vitro. They could strengthen the antiretroviral armamentarium and might be useful as microbicides.

Anti-Infective Agents↗
PubMed2003

Role of Baseline pol Genotype in HIV-1 Fitness Evolution.

Viral fitness can be modified upon development of antiretroviral drug resistance, usually by selection of compensatory mutations. In this study, we have used HIV-1 isolates from individuals receiving a protease inhibitor (PI)-based regimen to analyze the impact of basal genetic background on viral fitness evolution. Paired plasma samples and HIV-1 isolates were obtained from 10 PI-naive HIV-infected individuals enrolled in 2 different studies of combination antiretroviral therapy. Genomic regions from pol and env were sequenced. Viral fitness was measured using growth competition experiments followed by heteroduplex tracking analysis. Baseline genotypic analyses of pol showed that 9 of 10 viruses had a different degree of secondary mutations in the protease gene at codons associated with PI resistance (i.e., 10I, 36I, 63P, 71T, and 77I). After 48 weeks of PI-based therapy, a strong correlation was observed between protease genetic divergence and viral fitness difference (r = 0.78, P = 0.03), but not with reverse transcription or Env divergence, suggesting that genotypic changes in the protease gene were driving HIV-1 evolution in these patients. As expected, an inverse correlation was observed between the number of protease and reverse transcription primary mutations and viral fitness (r = -0.65, P < 0.0001). However, our results suggest that the preexistence of secondary mutations in protease genetic background may have implications in HIV-1 fitness evolution and virologic response to antiretroviral therapy.

Acquired Immunodeficiency Syndrome↗