Human Immunodeficiency Virus Type 1 Infected Individuals Research Articles

3-methylcholanthrene activates human immunodeficiency virus type 1 replication via aryl hydrocarbon receptor.

We found that 3-methylcholanthrene (3-MC) could induce the reactivation of human immunodeficiency virus type 1 (HIV-1) replication in OM 10.1 cell, promyelocytic cell line latently infected with HIV-1. Transient luciferase expression experiments have revealed no particular transcription factors that are responsible for the effect of 3-MC in inducing HIV-1 gene expression as HIV-1 LTR mutants lacking various upstream transcriptional activators similarly responded to 3-MC. In addition, there was no effect of 3-MC on the DNA binding activity of nuclear factor-kappa B (NF-kappaB) that was previously reported to be crucial for the effect of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD), a chemical homologue of 3-MC. However, overexpression of wild type aryl hydrocarbon receptor (AhR), a nuclear receptor of polycyclic aromatic hydrocarbons (PAHs) such as 3-MC, augmented the effect of 3-MC in the induction of gene expression from HIV-1 LTR. Moreover, a dominant negative mutant of AhR dramatically reduced the 3-MC-mediated activation of HIV-1 LTR. These findings suggest that 3-MC stimulates HIV-1 transcription by interacting with general transcription factors. Our observations indicate that chronic exposure of the HIV-1 infected individuals to PAHs may be contributable to the clinical development of acquired immunodeficiency syndrome (AIDS) among the individuals infected with HIV.

Tropism-restricted neutralization by secretory IgA from parotid saliva of HIV type 1-infected individuals.

In this study we examined secretory IgA, isolated from the parotid saliva of 10 HIV-1-infected subjects, for its ability to influence HIV-1 infection of peripheral blood mononuclear cells with two R5 and two X4 primary isolates. Salivary IgA from four subjects was found to inhibit both R5 viruses but not the X4 viruses. In another subject, salivary IgA inhibited both X4 viruses but not the R5 viruses. The specificity of these antibodies seemed to be directed against, but not restricted to, gp160 and gp120. Compared with subjects whose salivary IgA did not inhibit HIV-1 infection, subjects who displayed neutralizing activity were in relatively early stages of disease and had CD4(+) T cell counts greater than 200 cells/microl. Our data indicate the presence of tropism-specific (more frequently R5-specific) neutralizing antibodies in HIV-1-infected subjects. Because mucosal transmission of HIV-1 occurs exclusively in R5 viruses, and X4 viruses often emerge in established infection and account for viral persistence later in disease, our data suggest a potential role for secretory IgA in preventing viral transmission, but a less likely effect on chronic infection.

Fitness of drug resistant HIV-1: methodology and clinical implications.

Recent studies of human immunodeficiency virus type 1 (HIV-1) fitness have examined the potential relationship with plasma viral load, drug resistance, and disease progression. For example, treatment of HIV-1 infected individuals with antiretroviral drugs may result in the selection and emergence of inhibitor-resistant variants with reduced replicative capacity. However, it is still unclear whether in vitro HIV-1 fitness has any direct relationship to in vivo disease progression or treatment success. A related question is which in vitro assay of viral fitness is the most appropriate for comparison with in vivo HIV-1 fitness. Characterization of the relative viral fitness of drug-resistant HIV-1 strains may lead to a better understanding of whether or not less fit viruses pose a clinical benefit to the patient.

Detection of mucosal antibodies in HIV type 1-infected individuals.

HIV-1-specific mucosal IgA antibodies may correlate with protection in highly exposed but uninfected individuals, but have been detected at highly variable levels in HIV-1-infected individuals. To determine the best assays for detection of IgA antibodies in mucosal samples, rectal washes from 16 HIV-1-infected and 14 uninfected individuals were distributed to six laboratories experienced in detection of mucosal antibodies. Assays for HIV-1-specific IgA and IgG were performed in a blinded fashion by each of the laboratories using modifications of ELISA and chemiluminescence-enhanced Western blotting. Rectal washes contained easily detectable total IgA levels that did not differ between HIV-1-infected and uninfected groups. Irrespective of the assay used, HIV-1-specific IgA antibodies were absent in most samples; only one laboratory identified a higher frequency of positive samples from HIV-1-infected than uninfected individuals. In spite of 10-fold lower levels of total IgG than IgA, all but one laboratory identified HIV-1-specific IgG in most rectal washes of HIV-1-infected individuals. Comparable and readily detectable levels of influenza-specific IgA antibodies were present in nasal, salivary, and rectal secretions from both HIV-1-infected and uninfected individuals. These observations suggest a selective alteration in the production of HIV-1-specific IgA antibodies in HIV-1-infected individuals.

Enhanced culture method for detection of replication-competent virus in peripheral blood mononuclear cells of HIV type 1-infected individuals.

The detection of replication-competent human immunodeficiency virus type 1 (HIV-1) in infected individuals is integral for studies of viral latency and reservoirs of continuing replication during treatment. We describe a modified coculture method to detect/isolate virus from HIV-1-infected individuals with low or undetectable plasma viral loads. We observed a wide range in CD4 and chemokine receptor concentrations on CD4(+) T cells of HIV-1-uninfected donors. We selected cells from donors who expressed high levels of CCR5 after mitogen stimulation to combine in culture with peripheral blood mononuclear cells of HIV-1-infected individuals. Using this donor-enhanced culture method, viruses were isolated from asymptomatic adults with longterm nonprogressive infection, and children receiving effective highly active antiretroviral therapy, whereas parallel cultures with cells expressing lower levels of CCR5 yielded none. Virus was isolated from an individual for whom all previous attempts using reported methods were unsuccessful. Virus growth from cryopreserved cells from this same individual was detected at multiple sampling time points, including a time point at which a sensitive assay to measure 2-LTR (long terminal repeat) circular forms of the viral genome was negative. This will be a useful technique by which to study viral latency and HIV-1 pathogenesis in adult and pediatric populations.

Conserved Domains of Subtype C Nef from South African HIV Type 1-Infected Individuals Include Cytotoxic T Lymphocyte Epitope-Rich Regions

We have characterized 43 nef sequences from subtype C HIV-1-infected South Africans and compared deduced amino acid sequences with other subtypes to identify areas of conservation. Our Nef amino acid sequences were aligned with a consensus subtype B, HXB2 reference strain and a consensus subtype C sequence. All were found to be highly homologous to subtype B in the central region of Nef, but more variable at the N and C termini of the molecule. Alignment of a consensus amino acid sequence generated from South African subtype C Nef with subtypes A, B, and D underscores cross-clade conservation in the central domain of the molecule. This domain is also rich in previously described cytotoxic T lymphocyte (CTL) epitopes that are restricted by commonly found HLA molecules in the South African population.

Frequency of CCR5 gene 32-basepair deletion in Chilean HIV-1 infected and non-infected individuals

A 32-basepair deletion polymorphism in the CCR5 chemokine receptor gene (CCR5Δ32) has been identified and shown to have functional significance in determining susceptibility to infection by human immunodeficiency virus type 1 (HIV-1) and possibly in influencing disease progression in HIV-1 positive individuals. These findings led to an interest in studies of ΔCCR5 allele geographical distribution in human population, for complete understanding of the role of CCR5 in HIV-1 epidemiology. Inter-population variation in CCR5Δ32 frequency may be a significant factor in the prediction of AIDS endemicity. In this report we assessed the frequency of ΔCCR5 in a Chilean population (63 HIV-1 infected and 62 non-infected individuals). No homozygous CCR5Δ32 individual was identified, and no significant difference was observed between HIV-1 infected (3/63) and non-infected (3/62) individuals for the heterozygote CCR5Δ32 state. This is the first evidence of the contribution of ΔCCR5 allele to the genetic background of the Chilean population, which is characterized by intense ethnic admixture and by gene flow from the European Spanish gene pool.

Epidemiology and clinical features of HIV-1 associated neuropathies.

Peripheral neuropathy is common in human immunodeficiency virus type-1 (HIV-1) infection. Peripheral neuropathies complicate all stages of the HIV-1 disease and cause considerable morbidity and disability in HIV-1 infected individuals and acquired immunodeficiency syndrome (AIDS) patients. Whereas symptomatic neuropathies occur in approximately 10% to 15% of HIV-1-infected patients overall, pathologic evidence of peripheral nerve involvement is present in virtually all end-stage AIDS patients. There are 6 major clinical types of HIV-associated neuropathies that are regularly seen in large HIV-1 clinics. Distal sensory polyneuropathy (DSP) is the most common among the HIV-1-associated neuropathies. DSP generally occurs in later stages of HIV-1 infection and it follows an indolent and protracted clinical course. The dominant clinical features in DSP include distal pain, paresthesia and numbness in a typical length-dependent fashion with proximal to distal gradient. Whereas toxic neuropathies--secondary to certain antiretroviral agents--are clinically similar to DSP, their temporal relation to neurotoxic medication helps distinguish them from other HIV-1-associated neuropathies. DSP and toxic neuropathy may coexist in a single patient. Acute and chronic inflammatory demyelinating polyradiculoneuropathies (AIDP and CIDP) produce global limb weakness. AIDP may occur at seroconversion and it can therefore be the initial manifestation of HIV-1 infection. CIDP generally occurs in the mid to late stages of HIV-1 infection. Progressive polyradiculopathy (PP) occurs in patients with advanced immunodeficiency and is generally caused by the opportunist cytomegalovirus (CMV) infection. Mononeuropathy multiplex (MM) in early stages of HIV-1 infection is immune mediated, whereas in advanced AIDS it is caused by the CMV infection. Finally, subclinical autonomic nervous system involvement is common in all stages of HIV-1 infection. Because HIV-1-associated neuropathies are diverse in their etiology and pathogenesis, a precise clinical diagnosis is required to formulate a rational therapeutic intervention.

CD8(+) T-cell gamma interferon production specific for human immunodeficiency virus type 1 (HIV-1) in HIV-1-infected subjects.

The CD8(+)-T-cell response to human immunodeficiency virus type 1 (HIV-1) is considered to be important in host control of infection and prevention of AIDS. We have developed a single-cell enzyme immunoassay (enzyme-linked immunospot assay) specific for gamma interferon (IFN-gamma) production stimulated by either autologous B-lymphoblastoid cell lines (B-LCL) infected with vaccinia virus vectors expressing HIV-1 proteins or synthetic peptides representing known HIV-1 CD8(+) cytotoxic T-lymphocyte (CTL) epitopes. Single-cell IFN-gamma production stimulated by HIV-1 Gag-, Pol-, and Env-expressing B-LCL was a reliable measure of HIV-1-specific T-cell immunity in peripheral blood CD8(+) T cells from HIV-1 infected individuals. This method was more sensitive than stimulation of IFN-gamma by direct infection of the cultures with HIV-1-vaccinia virus vectors. Comparable results were found for IFN-gamma production in CD8(+) T cells from HIV-1-negative, cytomegalovirus (CMV)-seropositive, healthy donors stimulated with B-LCL expressing the CMV pp65 lower matrix protein. HIV-1 peptides were immunodominant for both CD8(+) single-cell IFN-gamma production and CTL precursor frequencies. The number of cells producing IFN-gamma decreased in individuals with late-stage HIV-1 infection and was temporally enhanced during combination antiretroviral therapy with two reverse transcriptase nucleoside inhibitors and a protease inhibitor.

HIV type 1 tat gene heteroduplex mobility assay as a tool to establish epidemiologic relationships among HIV type 1-infected individuals.

Molecular biology techniques are increasingly used to study the molecular epidemiology of infectious diseases. Most of these methods are expensive and labor-intensive. The human immunodeficiency virus (HIV) has substantial genomic variation, such that HIVs from different individuals are genetically diverse, although mutation rates differ for distinct regions of the genome. Most studies of HIV linkage and molecular evolution have focused on env or gag regions. We show that heteroduplex mobility analysis of the first exon of the HIV tat gene provides a simple, rapid, inexpensive, and reliable discriminatory tool for the molecular differentiation of shared versus distinct HIV-1 quasispecies when epidemiologic relations need to be defined. tat, as a relatively conserved region, appears to be a better region than the more variable env region to establish HIV-1 epidemiological linkages.

The Distribution of HIV‐1 Subtypes in Fukuoka, Japan

To determine the incidence of human immunodeficiency virus type-1 (HIV-1) subtypes in Fukuoka, Japan, viruses from 41 HIV-1 infected individuals were subtyped. Subtyping by V3-loop enzyme-linked immunosorbent assay (ELISA) showed 31 of the 41 subjects as subtype B (MN type), one as subtype A, one as subtype C, and eight untypable. The subject infected with subtype C was identified as a foreigner; the subtype A subject was Japanese. A phylogenetic analysis of nucleic acid sequences from the env C2-V3 region was also conducted. Genetic subtyping was successful for 25 samples: 23 samples were determined as subtype B, one subtype A and one subtype E. One of the individuals infected with subtype B, as well as the subtype A and subtype E subjects, were not Japanese. This study indicated that subtype B (USA and European type) is still dominant among HIV-1 infections in Fukuoka. Further, no Japanese were subtype E positive, which is increasing in the Kanto region. It is notable, however, that subtype A and subtype C infections, which are rare in Japan, were found in Fukuoka, located far from the metropolitan area of Tokyo.

High levels in serum, but no signs of intrathecal synthesis of anti-sulfatide antibodies in HIV-1 infected individuals with or without central nervous system complications

Myelin degeneration is commonly found in the central nervous system (CNS) of individuals infected with human immunodeficiency virus type 1 (HIV-1), especially in patients with HIV-1-associated dementia. We analysed cerebrospinal fluid (CSF) and serum samples from 25 HIV-1 infected individuals for the presence of antibodies directed against sulfatide, the major acidic glycosphingolipid in myelin. Nine of the patients had CNS complications, including 3 with HIV-1-associated dementia, and 16 had no neurological symptoms. Elevated titres of anti-sulfatide antibodies were found in serum from 24/25 HIV-1-infected individuals but in none of them in the CSF. Although the vast majority of HIV-1-infected individuals harbour autoantibodies directed against sulfatide in serum, the lack of detectable intrathecal production indicates that anti-sulfatide antibodies are not a major component in the pathogenesis of CNS myelin damage in HIV-1 infection.

Identification of human immunodeficiency virus type 1 subtypes B and F B/F recombinant and dual infection with these subtypes in Argentina.

DNA sequences encoding the third variable region (V3) of human immunodeficiency virus type-1 (HIV-1) envelope glycoprotein gp120 were obtained from 18 infected individuals residing in different regions of Argentina. Proviral DNA representing the env V3 region was obtained by PCR from uncultured peripheral blood mononuclear cells (PBMC) and genetic heterogeneity was examined by phylogenetic analysis. Sequences representing the gag p17 region were also obtained for a subset of these samples. Moreover, 1 sample that it was not possible to classify according to initial phylogenetic analysis was further analysed by molecular cloning of both V3 and p17 regions. Phylogenetic analysis according to different methodologies were performed comparing obtained sequences with a set of reference sequences representing previously characterized HIV-1 subtypes. The recombinant identification program (RIP) was used to study the presence of possible recombinant sequences. Phylogenetic analysis demonstrated that viruses representing both subtypes B and F are circulating among HIV-1 infected individuals in Argentina. In addition, RIP analysis showed that an initially unclassified sequence exhibited similarities to subtypes B and F in different fragments of the V3 region. Separate phylogenetic analysis of each of these fragments revealed divergent clustering, suggesting that this sequence harbours a point of recombination within the V3 loop. Interestingly, we also identified a dually infected individual with viruses belonging to subtypes B and F, as demonstrated by molecular cloning analysis of the env V3 and the gag p17 regions. Taken together, our study shows that both subtypes B and F are circulating in different regions of Argentina. Moreover, the data presented here show that dual infections with subtypes B and F can occur, and consequently B/F recombinant sequences are arising in the region.

Lack of in vitro anti-gp160 antibody production is a correlate of nonprogression among HIV type 1-infected individuals.

The aim of our study was to investigate the possible correlation of in vitro antibody production (IVAP) directed to the gp160 protein of HIV-1 with CD4+ slopes, plasma viremia, and disease progression in long-term nonprogressors (LTNPs). Nineteen subjects with a long-term nonprogressive HIV-1 infection were studied and followed for 2 years. During the follow-up, in vitro anti-gp160 producers showed negative CD4+ slopes in the majority of cases (9 of 12), whereas 5 of 7 nonproducers showed positive CD4+ slopes. Plasma viremia values, which were not significantly different in the two groups at baseline, became significantly higher in anti-gp160 producers when compared with nonproducers during the follow-up (p = 0.012). Finally, a trend toward progression was observed in the group of producers but not in nonproducers. These findings suggest that the in vitro production of anti-gp160 antibodies by peripheral B cells is not a correlate of protection, and may represent an early predictor of progression in LTNPs.

Evaluation of epidemiological and serological predictors of human immunodeficiency virus type-1 (HIV-1) infection among high risk professional blood donors with western blot indeterminate results.

Indeterminate pattern of results in Western blot (WBI) for human immunodeficiency virus type-1 (HIV-1) infection may represent early HIV-1 infection or may be non-specific in origin. This issue can be resolved by follow up testing upto at least 6 months resulting in psychological distress as well as in high drop out rates among those undergoing investigation pointing out the need for additional parameters that could help in determining the status of HIV-1 infection at the time of initial testing itself in individuals with WBI pattern. The objectives of the present study were: (i) to determine the frequency of HIV-1 infected individuals in a group of professional donors showing WBI patterns in initial testing on the basis of follow up serological studies; (ii) to find out if any HIV related epidemiological or serological characteristics recorded at the time of initial testing could be considered as predictor for HIV-1 infection in WBI specimens; and (iii) to evaluate two alternative serodiagnostic strategies for HIV-1 infection viz. multiple EIAs based on different antigen preparations/principles and a line immunoassay (LIA) employing recombinant antigens in resolving status of HIV-1 infection in specimens showing WBI results at initial testing. Professional donors with WBI patterns belonging to EIA reactive and EIA nonreactive groups were subjected to study of epidemiological profile, prevalence of sexually transmitted diseases (STD) markers and follow up serological testing for HIV-1 at 6, 12, 24 and 48 weeks intervals to record any seroconversion. The initial and follow up specimens from the donors with initial WBI results were subjected to two EIAs (one based on dot immunoassay using synthetic HIV-1 antigens and other based on microwell EIA using recombinant HIV-1 proteins) as well as to LIA. Professional donors with initial WBI results, from the EIA reactive group had higher proportion of unmarried individuals (90.3%), with history of heterosexual promiscuity (75%) and visit to STD clinics (36.1%) compared with the WBI donors from the EIA nonreactive group (72.7, 42.4 and 12.1%, respectively, P values < 0.001). Prevalence of antitreponemal antibodies was higher in the former group (16.7%) compared with the later group (1.5%, P value < 0.002). Seroconversion was recorded in 4 (7.3%) out of 55 EIA reactive WBI donors from the EIA reactive group that were characterised by high optical density (OD) values in EIA, 'p24 only' pattern of band in WB and positivity by LIA at the time of initial testing. LIA was found to be more reliable test compared with combination of EIAs to determine status of HIV-1 infection in WBI specimens at the time of initial testing. The present study points out that parameters like history of heterosexual promiscuity, prevalence of STD markers, high OD values in screening EIA, 'p24' only pattern of bands in WB and positivity by LIA could have individual predictive values for HIV-1 infection in specimens showing WBI pattern of results at initial testing.

Studies for dynamics of reverse transcriptase inhibiting antibody in sera from HIV-1 infected individuals

Antibodies inhibiting human immunodeficiency virus type 1 (HIV-1) reverse transcriptase activity (RTI-antibody), Binding inhibition antibody (BI-antibody) and polymerization inhibition antibody (PI-antibody) were investigated for their ability to inhibiting RT activity in 248 HIV-1 infected individuals and 99 healthy individuals. In BI-antibody, high titer samples were determined more in than in RTI- and PI-antibodies. No significance was indicated between AC, ARC and AIDS is any antibody, however, progression from AC to AIDS was poled to high titer and low titer in RTI- and BI-antibodies. Moreover, time course of each antibody levels in the same infected individuals were resulted in no change, going up or down through all the experimental term, though all samples were collected in AC. These results were suggested that the determination factor of each stage in HIV progression would be multiple, and that the various dynamics of RTI-, BI- and PI-antibodies in the same infected individuals might be caused in the term from HIV infection to AIDS progression, prognosis or appearing of the drug resistant strain but stages of the disease.

Downregulation of HLA class I antigen expression in CD4+ T lymphocytes from HIV type 1-infected individuals.

The expression of HLA class I antigens is downregulated in CD4+ T cells following in vitro HIV-1 infection. We determined whether the expression of HLA class I antigens is downmodulated in peripheral blood lymphocytes (PBLs) of HIV-1-positive subjects and whether this defect correlates with disease progression. A cohort of 62 HIV-1-seropositive individuals in different stages of disease was studied. Among these, four subjects were evaluated at yearly intervals for 6 years. The expression of HLA class I, HLA class II, and CD38 antigens was analyzed in PBLs and in CD4+ and CD8+ T lymphocyte subpopulations. The percentage of HLA class I-positive cells and the membrane density of HLA class I antigens were significantly lower in PBLs from HIV-1-positive individuals than in PBLs from HIV-negative controls, proportionally decreased with disease progression, and significantly correlated with the decrease in CD4+ T lymphocytes. Furthermore, the percentage of HLA class I-positive cells and the membrane density of HLA class I antigens were significantly lower in CD4+ T lymphocytes from AIDS patients with respect to CD4+ T lymphocytes from HIV-negative controls and to CD8+ T lymphocytes from HIV-negative controls and AIDS patients. By contrast, the expression of HLA class II and CD38 antigens was upregulated in CD4+ and CD8+ T lymphocytes from HIV-1-positive subjects. The defective expression of HLA class I antigens could impair the lysis of HIV-infected CD4+ cells by virus-specific HLA class I-restricted cytotoxic T lymphocytes and contribute to the progression of disease.

HIV Type 1 Subtype C in Addis Ababa, Ethiopia

HIV-1 variants in different geographic regions have been phylogenetically classified into the genetic subtypes A-I and O on the basis of sequence differences in the V3 regions of their gp120 envelope genes. The existence of all HIV-1 subtypes except subtype I has been confirmed in Africa. This paper describes the distribution of HIV-1 subtypes in Ethiopia. The first Ethiopian AIDS case was reported in 1986 and the AIDS epidemic has now become a rapidly growing problem in Addis Ababa the capital city. HIV-1 seroprevalence in the city is estimated to be 10-27% among pregnant women 47-59% among prostitutes and 7% among blood donors. Preliminary sequence data on a limited number of samples indicated the presence of subtype C in Addis Ababa in 1988. 94 sera collected from prostitutes pregnant women and blood donors during 1989-95 were analyzed to assess the distribution of HIV-1 subtypes in Addis Ababa. HIV-1 subtype C was identified in 93 of 94 cases. One case of subtype A virus was identified. Subtype C was also highly abundant also before the 1995 sera collection. Finally the authors discuss how the Ethiopian subtype C sequences differ slightly from the consensus C sequence.

Extrapulmonary pneumocystosis.

Extrapulmonary pneumocystosis is an exceedingly rare complication of Pneumocystis carinii pneumonia (PCP). Prior to the advent of the human immunodeficiency virus type 1 (HIV-1) epidemic, only 16 cases of extrapulmonary pneumocystosis in individuals who were immunocompromised by a variety of underlying diseases had been reported. Since the beginning of the HIV-1 and related PCP epidemic, at least 90 cases of extrapulmonary pneumocystosis have been reported. This review briefly presents a history of the discovery of P. carinii and its recognition as a human pathogen, the controversy regarding its taxonomy, and the epidemiology of this organism. A more detailed analysis of the incidence of extrapulmonary pneumocystosis in HIV-1-infected individuals and its occurrence despite widespread prophylaxis for PCP with either aerosolized pentamidine or systemic dapsone-trimethoprim is presented. The clinical features of published cases of extrapulmonary pneumocystosis in non-HIV-1-infected individuals are summarized and contrasted with those in HIV-1 infected individuals. The diagnosis of extrapulmonary pneumocystosis is discussed, and because clinical microbiologists and pathologists are the key individuals in establishing the diagnosis, the characteristic microscopic morphology of P. carinii as its appears when stained with a variety of stains is presented and reviewed. The review concludes with a brief discussion of treatments for extrapulmonary pneumocystosis.

Hematopoietic Potential and Retroviral Transduction of CD34+Thy-1+ Peripheral Blood Stem Cells From Asymptomatic Human Immunodeficiency Virus Type-1–Infected Individuals Mobilized With Granulocyte Colony-Stimulating Factor

AbstractThe potential of hematopoietic stem cells (HSCs) from human immunodeficiency virus type-1 (HIV-1)–infected individuals, eg, self-renewal and multilineage differentiative capacity, might be perturbed due to the underlying disease. In this study, we assessed the HSC activity in the CD34+Thy-1+ cell population of peripheral blood stem cells (PBSCs) of three asymptomatic HIV-1–infected individuals after granulocyte colony-stimulating factor (G-CSF; 10 μg/kg/d) mobilization. On day 4 of G-CSF treatment, 0.8% to 1% of the total blood mononuclear cells were CD34+. Leukapheresis followed by a two-step cell isolation process yielded a CD34+Thy-1+ cell population of high purity (76% to 92% CD34+Thy-1+ cells). This cell population showed no evidence of HIV-1–containing cells based on a semiquantitative HIV-1 DNA polymerase chain reaction. Furthermore, the purified cells showed normal hematopoietic potential in in vitro clonogenic assays. Successful gene transfer into committed progenitor cells (colony-forming units-cells) and more primitive stem/progenitor cells (long-term culture colony-forming cells) could be shown after amphotropic retroviral transduction. These data provide evidence that the CD34+Thy-1+ stem cell compartment can be mobilized and enriched in early stage HIV-1–infected patients. Furthermore, successful transduction of this cell population as a prerequisite for stem cell-based clinical gene therapy protocols was demonstrated.