Platelet-derived growth factor expression in primary pulmonary hypertension: comparison of HIV seropositive and HIV seronegative patients

Primary pulmonary hypertension (PPH) is characterized by intimal fibrosis and cell proliferation (including fibroblasts, smooth muscle and endothelial cells) in the distal pulmonary arterial tree. Considerable interest has been generated by recent reports of PPH in human immunodeficiency virus (HIV)-1-infected individuals. Although the lack of evidence for a pulmonary artery infection has suggested that in such cases HIV may act through mediator release rather than by direct endothelial infection, the mechanisms underlying HIV-associated PPH remain poorly defined. Platelet-derived growth factor (PDGF) has the ability to induce smooth muscle cell and fibroblast proliferation and migration. Given these considerations, we have attempted to document a possible role for PDGF in PPH occurring in HIV seropositive and seronegative patients. Using semiquantitative polymerase chain reaction (PCR), PDGF A-chain messenger ribonucleic acid (mRNA) expression was analysed in surgical lung biopsies from 13 HIV seronegative patients and one HIV seropositive patient, all displaying severe PPH. In parallel, lung samples from two patients with HIV-1-associated PPH were studied by immunohistochemistry and in situ hybridization. Results were compared to those obtained in three HIV-1-infected individuals with no pulmonary complication (as demonstrated by clinical, radiological, bacteriological, and necropsy findings) and five control lung biopsies. As compared to controls, PDGF A-chain mRNA expression is elevated in lung biopsies from patients displaying PPH (p=0.029). In HIV-1-associated PPH, interstitial perivascular cells expressing PDGF A-chain mRNA and protein could be detected by in situ hybridization and immunohistochemistry, respectively. Platelet-derived growth factor expression is elevated in lung biopsies of patients displaying primary pulmonary hypertension. Growth factors such as platelet-derived growth factor may play a part in the initiation and/or progression of primary pulmonary hypertension.     

Importance of ribosomal frameshifting for human immunodeficiency virus type 1 particle assembly and replication

The recent development and use of protease inhibitors have demonstrated the essential role that combination therapy will play in the treatment of individuals infected with the human immunodeficiency virus type 1 (HIV-1). Past clinical experience suggests that due to the appearance of resistant HIV-1 variants, additional therapeutics will be required in the future. To identify new options for combination therapy, it is of paramount importance to pursue novel targets for drug development. Ribosomal frameshifting is one potential target that has not been fully explored. Data presented here demonstrate that small molecules can stimulate frameshifting, leading to an imbalance in the ratio of Gag to Gag-Pol and inhibiting HIV-1 replication at what appears to be the point of viral particle assembly. Thus, we propose that frameshifting represents a new target for the identification of novel anti-HIV-1 therapeutics.     

Resistance to HIV-1 infection among persistently seronegative prostitutes in Nairobi, Kenya

BACKGROUND: There is indirect evidence that HIV-1 exposure does not inevitably lead to persistent infection. Heterogeneity in susceptibility to infection could be due to protective immunity. The objective of this study was to find out whether in highly HIV-1-exposed populations some individuals are resistant to infection. METHODS: We did an observational cohort study of incident HIV-1 infection-among 424 initially HIV-1-seronegative prostitutes in Nairobi, Kenya, between 1985 and 1994. 239 women seroconverted to HIV-1 during the study period. Exponential, Weibull, and mixture survival models were used to examine the effect of the duration of follow-up on incidence of HIV-1 infection. The influence of the duration of exposure to HIV-1 through prostitution on seroconversion risk was examined by Cox proportional hazards modelling, with control for other known or suspected risk factors for incident HIV-1 infection. HIV-1 PCR with env, nef, and vif gene primers was done on 43 persistently seronegative prostitutes who remained seronegative after 3 or more years of follow-up. FINDINGS: Modelling of the time to HIV-1 seroconversion showed that the incidence of HIV-1 seroconversion decreased with increasing duration of exposure, which indicates that there is heterogeneity in HIV-1 susceptibility or acquired immunity to HIV-1. Each weighted year of exposure through prostitution resulted in a 1.2-fold reduction in HIV-1 seroconversion risk (hazard ratio 0.83 [95% CI 0.79-0.88], p < 0.0001). Analyses of epidemiological and laboratory data, show that persistent seronegativity is not explained by seronegative HIV-1 infection or by differences in risk factors for HIV-1 infection such as safer sexual behaviours or the incidence of other sexually transmitted infections. Interpretation: We conclude that a small proportion of highly exposed individuals, who may have natural protective immunity to HIV-1, are resistant to HIV-1.     

Development of peptide vaccines inducing production of neutralizing antibodies against HIV-1 viruses in HLA-DQ6 mice

Peptide vaccines against HIV-1 were prepared according to the cassette theory that we had proposed previously. An amino acid sequence of B subtype consensus of the HIV-1 V3 region was introduced into the MHC binding component with a supermotif for various MHC class II. The peptide vaccines induced T-cell responses in the DQ6 mice in which only DQ6 molecules were expressed as MHC class II. By contrast, an original V3 peptide including the consensus sequence was non-immunogenic in the DQ6 mice. Antibodies obtained from the DQ6 mice immunized with the peptide vaccines neutralized laboratory B subtype strains of HIV-1 in vitro. It may be anticipated that these peptide vaccines protect infection of HIV-1 in DQ6 positive individuals.     

Evaluation of a dipstick method for the detection of human immunodeficiency virus infection

Serology has been a fundamental tool to prevent post-transfusional infection with human immunodeficiency virus (HIV) and for epidemiological surveys, the first step to attempt control of the pandemia. Enzyme immunoassay is in widespread use. Nevertheless, simpler methods are needed in many countries, where laboratory facilities and trained personnel are limited, and HIV prevalence is high. The evaluation of a simple and noninstrumented HIV antibody test is presented here. The test employs synthetic antigens of HIV-1 and HIV-2 attached to the teeth of a polystyrene comb, which fit into the wells of standard microtiter plates where samples are diluted. Captured antibodies are developed with colloidal gold-labeled Protein A. Three seroconversion panels plus 662 samples were tested, including HIV-1 and HIV-2-infected individuals, normal blood donors, and a noninfected baby born to a seroreactive mother. When compared with enzyme-linked immunosorbent assay (ELISA) and Western blot, the dipstick showed 100% sensitivity and 98.7% specificity. The simplicity of result evaluations and excellent reagent stability make the dipstick suitable for small blood banks and for epidemiological surveys.     

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.     

Reduction of diagnostic window by new fourth-generation human immunodeficiency virus screening assays

In order to reduce the diagnostic window between the time of human immunodeficiency virus (HIV) infection and laboratory diagnosis, new screening enzyme-linked immunosorbent assays (ELISAs) which permit the simultaneous detection of HIV antigen and antibody have been developed. Two fourth-generation assays, HIV DUO (Biomérieux) and HIV Combi (Boehringer Mannheim), for the combined detection of HIV antigen and antibody, were compared with a third-generation assay (HIV-1/HIV-2 3rd Generation Plus enzyme immunoassay [EIA]; Abbott) and a p24 antigen test (HIV-1 Ag monoclonal; Abbott). A total of 17 seroconversion panels, 15 cell culture supernatants infected with different HIV type 1 (HIV-1) subtypes, and 255 potentially cross-reactive serum samples were tested. Ten seroconversions were detected an average of 8.1 days earlier with HIV DUO and 7.5 days earlier with HIV Combi than with the third-generation ELISA. Overall, in the 17 seroconversion panels tested, HIV DUO detected HIV-1 infection an average of 4.8 days and HIV Combi detected infection an average of 4.4 days earlier than HIV-1/HIV-2 3rd Generation Plus EIA. HIV antigen was detected with HIV DUO and HIV Combi in all of the 15 cell culture supernatants infected with different HIV-1 subtypes, including subtype O. With fourth-generation assays, considerably fewer false-positive results (n = 4 to 6) were obtained, in comparison with the third-generation EIA (n = 18). Fourth-generation assays permit an earlier diagnosis of HIV infection than third-generation antibody screening assays through the detection of p24 antigen, which may be present in serum samples from individuals with recent HIV infection prior to seroconversion.     

Multibranched V3 peptides inhibit human immunodeficiency virus infection in human lymphocytes and macrophages

Synthetic polymeric constructions (SPCs) including the consensus sequence of the human immunodeficiency virus type 1 (HIV-1) surface envelope glycoprotein gp120 V3 loop (GPGRAF) blocked the fusion between HIV-1- and HIV-2-infected cells and CD4+ uninfected cells. A structure-activity relationship study using V3 SPC analogs showed that the most efficient inhibitor of cell fusion was an eight-branched SPC with the hexapeptide motif GPGRAF (i.e., [GPGRAF]8-SPC). N-terminal acetylation or incorporation of D-amino acids in the GPGRAF sequence of this SPC resulted in significant loss of activity. Analogs with fewer than six residues in the motif (i.e., GPGRA or GPGR), as well as SPCs with a nonrelevant sequence, did not inhibit cell fusion, demonstrating the high specificity of the antifusion activity. [GPGRAF]8-SPC, which was not toxic to CEM cells at concentrations of up to 50 microM, inhibited 50% of HIV-1(LAI) replication in these cells at a concentration of 0.07 microM. Moreover, [GPGRAF]8-SPC inhibited the infection of human peripheral blood mononuclear cells by several HIV-1 and HIV-2 isolates, including laboratory strains [HIV-1(LAI), HIV-1(NDK), and HIV-2(ROD)], and fresh primary isolates, including two zidovudine-resistant HIV-1 isolates and two HIV-2 isolates obtained from infected individuals. The multibranched peptide also inhibited infection of human primary macrophages by the highly cytopathic macrophage-tropic isolate HIV-1(89.6). The antiviral activity of [GPGRAF]8-SPC was not related to a virucidal effect, since preincubation of HIV-1 with the peptide did not affect its infectious titer. This result is in agreement with the concept that the multibranched peptide mimics a part of the V3 loop and thus interacts with the host cell. The therapeutic properties of synthetic multibranched peptides based on the V3 loop consensus motif should be evaluated in HIV-infected patients.     

Evaluation of the Nuclisens HIV-1 QT assay for quantitation of human immunodeficiency virus type 1 RNA levels in plasma

Nuclisens HIV-1 QT is a new version of the NASBA HIV-1 QT assay for quantitation of human immunodeficiency virus type 1 (HIV-1) RNA in plasma. The specificity of this assay was 100% in one laboratory and 99%-with nonrepeatability of the initial false positive-in another. The test was linear between 2.0 and 6.0 log RNA copies per ml. According to the input HIV-1 RNA concentration, accuracy varied from -0.11 to +0.10 log RNA copy per ml and precision varied from 0.66 to 0.14 log RNA copy per ml. Reproducibility decreased when the HIV-1 RNA level was near the lower limit of quantitation of the test. HIV-1 RNA could be quantitated by Nuclisens HIV-1 QT in 36% (laboratory 1) and 24% (laboratory 2) of clinical samples with HIV-1 RNA levels lower than the lower limit of quantitation by NASBA HIV-1 QT. Nuclisens HIV-1 QT was not suitable for measurement of RNA from clade G and group O HIV-1 strains.     

Salmonella lung involvement in patients with HIV infection

STUDY OBJECTIVE: To determine the frequency, clinical features, and outcome of lung involvement in HIV-infected patients having nontyphoid strains of Salmonella bacteremia. DESIGN: A retrospective clinical study. PATIENTS AND SETTING: We studied the records of all HIV-infected patients with Salmonella bacteremia diagnosed at a university tertiary hospital from January 1987 to December 1995. RESULTS: Lung involvement was found in 18 (35.3%) of 51 HIV-infected individuals with Salmonella bacteremia. Six of 18 (33.3%) were diagnosed as having definite Salmonella pulmonary infection by isolation of Salmonella from respiratory specimens, while probable Salmonella lung disease was considered in two patients who developed lung abscesses without the identification of any pathogen. Predisposing factors for focal disease, such as prior lung disease or Salmonella serotype, were equally prevalent regardless of the presence of Salmonella pulmonary involvement. Cavitary infiltrates or abscess formation were seen in five of the eight patients. With the exception of one patient coinfected with Nocardia asteroides who died 1 month later, all patients were cured with antibiotic treatment. Superinfection with other pulmonary pathogens (10 cases, 56%) was more frequent than Salmonella pneumonia; the most frequent alternative diagnosis was Pneumocystis carinii pneumonia (5 cases, 28%), pyogenic bacterial infection (17%), and tuberculosis (11%). CONCLUSIONS: In HIV-infected patients with Salmonella bacteremia, lung involvement is frequent, although there were no significant factors to explain this association. Cavitary disease was the most common radiologic pattern, and focal lung disease due to Salmonella does not seem to be associated with a worse prognosis. Coinfection and superinfection with other respiratory pathogens are more common than isolated Salmonella lung disease, and therefore, additional diagnostic procedures must be considered in the evaluation of these patients.     

Heterozygosity for a defective gene for CC chemokine receptor 5 is not the sole determinant for the immunologic and virologic phenotype of HIV-infected long-term nonprogressors

HIV-1-infected long-term nonprogressors are a heterogeneous group of individuals with regard to immunologic and virologic markers of HIV-1 disease. CC chemokine receptor 5 (CCR5) has recently been identified as an important coreceptor for HIV-1 entry into CD4+ T cells. A mutant allele of CCR5 confers a high degree of resistance to HIV-1 infection in homozygous individuals and partial protection against HIV disease progression in heterozygotes. The frequency of CCR5 heterozygotes is increased among HIV-1- infected long-term nonprogressors compared with progressors; however, the host defense mechanisms responsible for nonprogression in CCR5 heterozygotes are unknown. We hypothesized that nonprogressors who were heterozygous for the mutant CCR5 gene might define a subgroup of nonprogressors with higher CD4+ T cell counts and lower viral load compared with CCR5 wild-type nonprogressors. However, in a cohort of 33 HIV-1-infected long-term nonprogressors, those who were heterozygous for the mutant CCR5 gene were indistinguishable from CCR5 wild-type nonprogressors with regard to all measured immunologic and virologic parameters. Although epidemiologic data support a role for the mutant CCR5 allele in the determination of the state of long-term nonprogression in some HIV-1- infected individuals, it is not the only determinant. Furthermore, long-term nonprogressors with the wild-type CCR5 genotype are indistinguishable from heterozygotes from an immunologic and virologic standpoint.     

Evaluation of human immunodeficiency virus type 1 (HIV-1)-specific cytotoxic T-lymphocyte responses utilizing B-lymphoblastoid cell lines transduced with the CD4 gene and infected with HIV-1

Analysis of major histocompatibility complex-restricted cytotoxic T lymphocytes (CTL) capable of killing human immunodeficiency virus type 1 (HIV-1)-infected targets is essential for elucidating the basis for HIV-1 disease progression and the potential efficacy of candidate vaccines. The use of primary CD4+ T cells with variable infectivity as targets for such studies has significant limitations, and immortal autologous cells with high levels of CD4 expression that can be consistently infected with HIV-1 would be of much greater utility. Therefore, we transduced Epstein-Barr-virus-transformed B-lymphoblastoid cell lines (LCL) with a retroviral vector, LT4SN, containing the human CD4 gene. Stable LCL in which more than 95% of cells expressed membrane CD4 were obtained. Aliquots were infected with HIV-1, and, after 4 to 7 days, nearly all of the cells contained cytoplasmic gag and produced high levels of p24 antigen. The ability of major histocompatibility complex-restricted CD8+ CTL to lyse such HIV-1-infected CD4-transduced LCL (LCL-CD4HIV-1) was evaluated. These autologous targets were lysed by CTL generated from an HIV-1-uninfected vaccinee over a broad range of effector-to-target ratios. Similarly, the LCL-CD4HIV-1 were efficiently lysed by fresh circulating CTL from HIV-1-infected individuals, as well as by CTL activated by in vitro stimulation. Both HIV-1 env- and gag-specific CTL effectors lysed LCL-CD4HIV-1, consistent with the cellular expression of both HIV-1 genes. The LCL-CD4HIV also functioned as stimulator cells, and thus are capable of amplifying CTL against multiple HIV-1 gene products in HIV-1-infected individuals. The ability to produce HIV-1-susceptible autologous immortalized cell lines that can be employed as target cells should enable a more detailed evaluation of vaccine-induced CTL against both homologous and disparate HIV-1 strains. Furthermore, the use of LCL-CD4HIV-1 should facilitate the analysis of the range of HIV-1 gene products recognized by CTL in seropositive persons.     

Altered cortical blood flow in HIV-seropositive individuals with and without dementia: a single photon emission computed tomography study

OBJECTIVE: To quantitatively demonstrate the pattern of cerebral perfusion abnormalities in HIV-1-infected individuals described as 'patchiness' or inhomogeneity in previous qualitative emission tomographic imaging studies. DESIGN: We aimed to create a quantitative measure of inhomogeneity in HIV-infected individuals. High-frequency variance in cortical profiles is an indication of inhomogeneity in the distribution of radiotracer in the cerebral cortex. Therefore, the study analysis was designed to enable the estimation of variance frequencies in cortical profiles. METHODS: Regional cerebral blood flow was examined in nine mildly demented and 10 cognitively normal HIV-1-seropositive individuals and eight seronegative normal controls using single photon emission computed tomography with the radiotracer [I-123]-N-isopropyl-p-iodoamphetamine. Quantitative analysis was performed using circumferential profiles of cerebral cortical perfusion. Fourier transform power spectra of the profiles were examined as an index of patchiness in tracer distribution. RESULTS: Normal controls were characterized by strong middle frequency and weak high-frequency power. Both HIV-1-infected groups showed a significant power shift from middle to high frequencies. CONCLUSIONS: Increased high-frequency variations in both HIV-1-infected groups indicates diffuse cortical perfusion changes compared with normal controls. This study suggests that there are cerebral bloodflow abnormalities in HIV-1-infected individuals both with and without clinically severe dementia.     

HLA antigens associated with susceptibility/resistance to HIV-1 infection

We studied the distribution of HLA-A, B, C, DR and DQ antigens in a cohort of HIV-1+ individuals and their heterosexual HIV seropositive (concordant) or seronegative (discordant) partners of Black non-Hispanic, Hispanic or Caucasian non-Hispanic ethnicity. The prevalence of DQ7 and Cw7 was significantly higher in the HIV-1+ compared to seronegative Black and Hispanic individuals, respectively. The frequency of DQ4 was significantly elevated in the Black seronegatives, whereas B53 was increased in the Hispanic seronegatives in comparison to the seropositives. No significant differences were observed between the Caucasian HIV infected and non-infected individuals. Analysis of the primary concordant HIV+ and discordant HIV+ individuals showed a marked increase in the prevalence of B44 in the Hispanic discordant seropositives, whereas the Caucasian primary concordants had a marked increase in the prevalence of A26. The prevalence of DQ7 and Cw7 was significantly increased in the Black and Hispanic secondary concordant seropositives, respectively in comparison to the seronegatives. The proportion of couples with matching HLA antigens was similar among the HIV-1+ concordant and discordant groups. These results provide additional evidence that HLA polymorphism may confer a genetic risk or protection for HIV-1 infection in individuals of various ethnic backgrounds.     

Diagnosis of pneumocystis carinii pneumonia in AIDS patients

BACKGROUND: Based on the changing disease pattern of human immunodeficiency virus (HIV) associated pulmonary complications we conducted a prospective study in order to compare the value of laboratory tests in patients with Pneumocystis (P.) carinii pneumonia (PCP) and other pulmonary complications and of different identification methods of P. carinii in bronchoalveolar lavage fluid (BALF) in PCP patients. PATIENTS AND METHODS: In 217 HIV-1-infected patients we evaluated the following parameters: platelets, serum lactat dehydrogenase (LDH), total serum protein (TP), hemoglobin (Hb), and CD4+ and CD8+ T-lymphocyte count. P. carinii was identified in BALF by May Grünwald Giemsa stain (MGG), direct immunofluorescence test (DIFT), and polymerase chain reaction (PCR). We correlated these parameters in patients with a presumptive diagnosis of PCP and compared them with those of patients suffering from other pulmonary complications. RESULTS: All patients underwent bronchoscopy. 55 patients (25.3%) had a presumptive diagnosis of PCP. The sensitivity values of MGG stain, DIFT, and PCR differed considerably (79.1%, 56.1%, and 65.9%, respectively), but specificity values did not (99.2%, 97.3%, and 98.2%, respectively) as well as accuracy values (93.8%, 86.2%, and 89.7%, respectively). The mean values of platelets, of LDH, and of total serum protein of PCP patients and those of patients with other pulmonary diseases differed statistically significant as well as the mean values of these parameters of PCP patients and those of patients with bacterial pneumonia. Logistic-regression analysis revealed the number of platelets and the amount of total serum protein as independent, significant prognostic factors. Moreover, each PCP patient had a CD4+ T-lymphocyte count of less than 200 cells/mm3 blood. The CD4/CD8 ratio of PCP patients was statistically significant lower than that of patients with bacterial pneumonia. CONCLUSIONS: A detection of P. carinii in BALF is inevitable for a definitive diagnosis of a PCP. The most efficient identification method in this case is the MGG stain. Platelets, total serum protein, and CD4+ T-lymphocyte count should be included into the criteria for the presumptive diagnosis of PCP.     

Differential susceptibility of naive and memory CD4+ T cells to the cytopathic effects of infection with human immunodeficiency virus type 1 strain LAI

CD4+ T lymphocytes of individuals infected with human immunodeficiency virus type 1 (HIV-1) exhibit a qualitative defect in their ability to mount memory responses to previously encountered antigens although their responses to mitogens remain normal. T cells responsible for memory responses can be distinguished from naive T cells based on differential expression of isoforms of the tyrosine phosphatase CD45. It has been suggested that memory CD4+ T cells from infected individuals have a greater virus burden than naive CD4+ T cells and that this accounts for the loss of recall responses in infected individuals. However, it has been unclear whether naive and memory T cells are equally susceptible to infection and to the cytopathic effects of the virus. We therefore infected highly purified resting naive and memory CD4+ T cells from HIV-1-seronegative individuals with HIV-1(LAI). Infected cells were then stimulated with phytohemagglutinin to render them permissive for viral replication. Cell viability and growth rate were monitored for 8 to 10 days as indicators of cytopathic effects induced by HIV-1(LAI). Our results indicated that naive and memory CD4+ T cells display marked differences in susceptibility to the cytopathic effects induced by HIV-1(LAI), infection. The cytopathic effects induced by HIV-1(LAI) were much more severe in memory CD4+ T cells than in naive CD4+ T cells. Differential cytopathic effects in naive and memory T cells were not due to differences in virus entry into and replication in these cell populations. Rather, memory cells were more susceptible to cytopathic effects. Pronounced cytopathic effects in memory cells were clearly detectable at 7 day postinfection. Cell death occurred at the single-cell level and was not accompanied by syncytium formation. The growth rate of infected memory CD4+ T cells was also severely compromised compared to that of naive CD4+ T cells, whereas the growth rates of both uninfected naive and memory CD4+ T cells were approximately the same. At least a portion of the dying cells exhibited biochemical changes characteristic of apoptosis. These results suggest that the selective functional defects present in the memory CD4+ T-cell subset of HIV-1-infected individuals may in part be the result of the greater susceptibility of memory T cells to cytopathic effects induced by HIV-1.     

Infection of human primary renal epithelial cells with HIV-1 from children with HIV-associated nephropathy

Children affected with human immunodefficiency virus (HIV)-associated nephropathy (HIVAN) usually develop significant renal glomerular and tubular epithelial cell injury. The pathogenesis of these changes is not clearly understood. Human renal tubular epithelial cells (RTEc) do not express CD4 surface receptors, and it is not clear whether these cells can be infected by HIV-1. Certain strains of HIV-1, however, have been shown capable of infecting CD4-negative epithelial cell lines. We hypothesized that the inability of laboratory strains of HIV-1 to infect renal epithelial cells may be due to a limited tropism, as opposed to wild-type viruses derived from children with HIVAN, and that viruses derived from these children are capable of infecting RTEc from the same patient. Here, we have demonstrated that HIV-1 isolates from children with HIVAN can productively infect RTEc through a CD4 independent pathway, and that infected mononuclear cells can transfer the virus to human RTEc. Human RTEc sustained low levels of viral replication and HIV-1 inhibited the growth and survival of cultured human RTEc. Thus, HIV-1 may directly induce degenerative changes in RTEc of children with HIVAN. Infected macrophages may play a relevant role in this process by transferring viruses to RTEc.     

Genetic characterization of viral quasispecies in blood and cervical secretions of HIV-1- and HIV-2-infected women

We evaluated cervical samples from 11 HIV-1- and 25 HIV-2-infected individuals. The rate of viral shedding was 36.4% for HIV-1 and 16% for HIV-2, after repeat PCRs. We sequenced multiple clones of the C2-C3 env region from cervical secretions and PBMC samples from three HIV-2-infected individuals, and the C2-V3 env region from four HIV-1-infected individuals. In most cases, phylogenetic analysis showed that the viral sequences from blood and genital secretions were intermingled and subclusters did not segregate according to sample site. In rare cases, however, tissue-specific sequences were observed, suggesting a complex relationship between quasispecies in the two sites where preferential transmission of HIV variants may be due to multiple factors.     

The CCR5 receptor acts as an alloantigen in CCR5Delta32 homozygous individuals: identification of chemokineand HIV-1-blocking human antibodies

The chemokine receptor CCR5 is the major coreceptor for infection by macrophage-tropic R5 HIV-1. A 32-bp deletion in the gene coding for CCR5 (CCR5Delta32) occurs with a frequency of 10% in the Caucasian population and results in a receptor protein that is truncated and not expressed at the cell surface. CCR5Delta32 homozygous individuals are apparently normal but resistant to infection with R5 HIV-1. In two individuals homozygous for CCR5Delta32, who had been repeatedly exposed to CCR5-expressing blood cells through sexual activity, we have identified antibodies to CCR5 that bound specifically to the surface of CCR5-expressing cell lines. Serum from these individuals, in contrast to serum from CCR5(+/+) individuals, competed with radiolabeled RANTES for binding to the CCR5 receptor and inhibited infection of peripheral blood mononuclear cells with R5, but not X4, primary isolates of HIV-1. The identified human antibodies to CCR5 define an alloantigen that may cause allograft rejection in a mismatch situation even in individuals with no history of blood transfusions or i.v. drug abuse.