摘要:

This review describes some of the virus-cell relationships that might contribute to the state of latency observed in HIV infection. Viruses use many mechanisms to persist in their host, and the molecular interactions evoked by the virus and the cell on each other can influence the outcome of an infection. The topics of cellular effects on the virus versus viral effects on the cell are discussed in the context of viral life-cycle, activation and defective viruses, as well as latency concepts in relation toin vivofindings andin vitrocell models.

ISSN:0269-9370    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ObjectiveThe purpose of this study was to develop and characterize human monoclonal antibodies (HuMAb) that neutralize HIV-1.DesignBased upon previous studies involving the generation of HuMAb that neutralize other enveloped viruses, we thought it feasible to generate HuMAb that might neutralize HIV-1.MethodsA HuMAb was generated by fusing splenic B-cells from an HIV-positive patient with a mouse myeloma cell line. Flow cytometry was used to determine surface reactivity of the HuMAb on HIV-infected and non-infected cells. Radioimmuno-precipitation was employed to elucidate the antigen recognized by the HuMAb. A cell survival assay was used to determine the ability of the HuMAb to neutralize divergent isolates of HIV-1 in the presence or absence of complement. A gp120-CD4 inhibition enzyme-linked immunosorbent assay (ELISA) was developed in order to initiate studies to determine the mechanism of neutralization by the HuMAb.ResultsAn anti-HIV HuMAb was generated that neutralized two HIV-1 isolates (IIIB and MN) without complement and which neutralized one divergent isolate (RF) and one clinical isolate in the presence of complement. This HuMAb, designated S1–1, was found, by flow cytometric analysis, to react with the surface of HIV-1-infected but not with uninfected cells. Radioimmunoprecipitation analysis demonstrated that S1–1 binds to native HIV gp120, but not dithiothreitol (DTT)-treated gp120. In addition, HuMAb S1–1 did not bind to denatured HIV antigens in Western blot analysis. HuMAb S1–1 effectively inhibited the binding of gp 120 to soluble CD4 in ELISA.ConclusionsThese results suggest that the epitope recognized by S1–1 is con-formational and conserved among diverse HIV-1 isolates and may represent an uncharacterized HIV neutralizing domain within or close to the CD4 binding domain on gp120. HuMAb S1–1 might have a role to play in vaccine development or passive immunotherapy.

ISSN:0269-9370    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ObjectiveTo study the immunological and immunohistochemicai nature of HIV-1 Nef.DesignMonoclonal anti-Nef antibodies were generated and used to identify antigenic epitopes in Nef, to study immunological cross-reactivity between Nef from different isolates and to reveal the subcelluiar localization of Nef.MethodsMonoclonal antibodies against recombinant HIV-1 Nef protein (BRU isolate) were generated in BALB/c mice. The epitope mapping was carried out with the use of overlapping 15–20mer lipopeptides linked to a lipid group at the amino-terminus. Immunoperoxidase method was used for histochemical studies.ResultsTen stable antibody-producing clones, mainly of the immunoglobulin (Ig) G1 subtype, with strong Western blot and enzyme-linked immunosorbent assay reactivity toward the recombinant Nef protein, were obtained. The epitopes recognized were located on amino-acid sequences 21–41, 31–50, 51–71, 61–80, 151–170, 161–180, and 171–190. All 10 monoclonal antibodies also reacted with the native Nef of HIV-1BRU, and eight reacted with native HIV-1IIIB. Most antibodies also reacted with Nef from more divergent HIV-1 strains. In Western blotting, two forms of Nef (24 and 27 kDa) were observed with most isolates studied. Immunohistochemical staining of HIV-1 -infected H9 or MT-4 lymphoid cells demonstrated that Nef was expressed mainly in the Golgi complex and at the nuclear membrane, but occasionally also in the nucleus. The nuclear localization of Nef was especially frequent in the HIV-1-infected MT-4 cells.ConclusionsOur findings suggest that Nef is expressed in two isomorphic forms, and that it may also act as a nuclear protein and thus have a direct regulatory function at the RNA/DNA level.

ISSN:0269-9370    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ObjectiveTo characterize antibody- and complement-mediated binding and uptake of HIV-1 by human monocytes.DesignThe first step in the infection of the monocyte by HIV-1 is binding of the virus to the susceptible cell. Procedures were designed to assess the influence of anti-HIV-1 antibodies and complement on this binding, and to study the process of internalization following binding.MethodsHuman monocytes were incubated with fluorescein-labelled purified HTLV-IIIBvirions and human sera with high-titre anti-HIV-1 antibodies and/or complement. Binding and uptake of virus by the monocytes was measured as fluorescence per cell by flow cytometry.ResultsBinding of purified HIV-1 to monocytes was increased by complement and, to a lesser extent, by anti-HIV-1 antibodies. Uptake of HIV-1 bound to the monocyte appeared to be mediated by antibodies and was increased further by the presence of complement. Complement alone, however, resulted in the uptake of only a small part of the bound virus.ConclusionsComplement significantly increases the binding of HIV-1 to human monocytes, and a combination of antibodies and complement efficiently mediates uptake of HIV-1 by monocytes.

ISSN:0269-9370    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ObjectiveTo determine the effects of HIV-1 antibody level and test-format characteristics on testing pooled sera.DesignThis study was designed with a laboratory exercise followed by test observations on serosurveillance samples.MethodsSera with low, medium and high (n = 22, 12 and 20, respectively) antibody titers were pooled with HIV-1-negative sera and tested with two enzyme-linked immunosorbent assays (ELISA) and a particle agglutination test. The same kits were used to test single and pooled (batches of five, 10 and 20) samples collected from 3000 blood donors and sex workers. These samples were then seeded with 50 varying antibody-containing sera and similarly tested. Initial reactivities, sensitivities, and specificities for all test kits were calculated and compared.ResultsIn the laboratory exercise, all reactive pools of five were detected. False-negative pools in batches of 10 and 20 with low antibody titers were noted with one or both ELISA, but not with the particle agglutination method. Testing 3000 samples revealed three confirmed reactive samples and 100% sensitivity/specificity for all kits, for both single and pooled sera testing. Increased initial reactivity (IR) was noted for the two ELISA. Examinations of pools of the seeded 3000 samples with the two ELISA showed false-negative reactivity with pools of 10 and 20 when pools contained low antibody sera (sensitivities and specificities of 92–97.9% and 98.1–100%, respectively). Again, increased IR was seen with the ELISA. False-negative pool and increased IR was not seen with the agglutination test (sensitivity/specificity 100%).ConclusionsWe recommend the use of the particle agglutination assay for testing pooled sera of batches of 20 or less. Components of reactive pools should then be tested and reactive samples should undergo supplementary testing. Pooled samples tested by ELISA should not exceed five per batch. Retesting of reactive pools, testing of its components, and supplemental test(s) of reactive sera should then follow. The optimum pool size for most laboratories is five, with the best technical and economic performance seen with the particle agglutination assay.

ISSN:0269-9370    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ObjectiveWe have previously demonstrated that detection of syncytium-inducing (SI) HIV-1 in asymptomatic seropositive individuals is associated with rapid progression to AIDS. In the present study, we sought to develop and evaluate an HIV-1 phenotyping assay for the screening of large numbers of individuals.MethodsEfficiency of HIV-1 isolation from patient peripheral blood mononuclear cells (PBMC) was studied with donqr PBMC or seven different CD4 + T-cell lines as target cells. The biological phenotype of sequential isolates from 20 long-term asymptomatic HIV-1-seropositive individuals was determined by two different assays.ResultsNon-SI isolates, efficiently recovered by cocultivation with donor PBMC, were never isolated with T-cell lines as target cells. Direct cocultivation with MT-2 cells, but not with six other CD4+ T-cells, resulted in the efficient recovery of SI isolates. HIV-1 MT-2 tropism and SI capacity were shown to be coupled properties at the clonal level. SI isolates emerged in 10 out of 20 longitudinally-studied individuals. In these long-term infected individuals, appearance of SI isolates was associated with progression to AIDS.ConclusionsDirect cocultivation of patient PBMC with the MT-2 cell line is a sensitive, specific and convenient method to detect SI isolates. The availability of an assay suitable for the screening of large groups allows further study of the value of HIV-1 biological phenotyping as a prognostic marker.

ISSN:0269-9370    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ObjectiveRecent studies have shown that B-cells from HIV-infected patients can secrete anti-HIV antibodiesin vitroand that they represent 20–40% of immunoglobulin (Ig)-secreting B-cellsin vivo.This study was designed to investigate the precise role of HIV in thisin vitroantibody production.Design and methodsB-cells from HIV-infected patients [asymptomatic, n = 28; symptomatic (AIDS), n = 14], from seronegative adult volunteers (n = 22) and subjects at high risk for HIV infection (n = 15) were culturedin vitroin the presence of pokeweed mitogen,Staphylococcus aureuscowan or HIV, and T-cells or interleukins (IL). Non-specific Ig production and specific anti-HIV antibody (Ab) production were measured by enzyme-linked immunosorbent and Western blot assays.ResultsWe found that HIV induced a specific response in cultured B-cells from seropositive patients, in contrast with cultured B-cells from uninfected normal individuals. The characteristics of the HIV-induced response differed from those of a spontaneous or a mitogen-induced response. Anti-HIV Ab production was optimal on day 8–10, when B-cells were cultured with recombinant IL-2 and recombinant interferon-α in the presence of infectious virus or recombinant gp160 Env protein. The anti-HIV Ab were mainly directed against Env proteins. Interaction of HIV with B-cells involved surface IgG but not CD4 antigen. Autologous CD8+ T-cells had a non-specific inhibitory effect. Both CD5 + and CDS - B-cells produced anti-HIV Ab. No anti-HIV Ab production was observed in B-cells from high-risk HIV-seronegative individuals.ConclusionHIV (infectious virus or gp160) can induce B-cells from infected patients to secrete specific anti-HIV Abin vitro.

ISSN:0269-9370    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ObjectiveTo detect and quantify HIV-1 in the liverin vivo.Design: Fourteen liver biopsy samples and corresponding blood lymphocytes and monocytes from patients with AIDS were studied for HIV-1 using quantitative polymerase chain reaction (PCR). In addition, expression of HIV-1 antigen and messenger (m) RNA in 10 autopsy liver specimens was examined by immunohistochemistry andin situhybridizationResultsThe amount of HIV-1 DNA in nine liver samples ranged from 850 to 27000 copies per 106cells, with mean and median values of 8150 and 3500 copies per 106cells, respectively. Five other samples had no detectable HIV-1 DNA by PCR. Intracellular expression of HIV-1 antigen and mRNA was also detected in both Kupffer cells and hepatocytes byin situstudies.ConclusionThese findings strongly indicate that HIV-1 could replicate in the liver of a majority of patients with AIDS.

ISSN:0269-9370    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ObjectiveTo investigate competitive interactions between zidovudine-sensitive and resistant strains of HIV within the context of host-parasite population dynamic interactions between CD4 + cells and HIV.DesignA mathematical model of the population dynamics of CD4 + cells, sensitive HIV and resistant HIV is developed.MethodsThe model is analysed numerically and analytically and model predictions are compared with previously published data on population dynamics of HIV and CD4 + cells in patients receiving zidovudine. A threshold result describing the critical dose of zidovudine above which resistant HIV will out-compete sensitive HIV is derived, as are expressions describing the critical effective doses for the eradication of sensitive and resistant strains. Numerical simulations of the dynamics of the shift from the pre-treatment, equilibrium to the treatment equilibrium are presented and an analytic expression approximating the time taken until virus growth restarts is derived.ResultsIt is shown that competition between strains of virus is the important factor determining which type of virus will eventually start to grow during the course of zidovudine treatment, but host-parasite interactions are the important determinant of when viral resurgence occurs.ConclusionsAlthough resistant strains are observed after prolonged treatment with zidovudine, this model suggests that it is the growing supply of uninfected CD4 + cells which causes the eventual upsurge in viral burden.

ISSN:0269-9370    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ObjectiveTo evaluate the epidemiology ofCandida albicansinfection in HIV-infected patients with oral lesions using molecular techniques.MethodsThirty-nine isolates from HIV-positive patients with oral candidiasis were examined using two DNA probes (aHistoplasma capsulatumribosomal DNA probe that cross-hybridizes with C.albicansand a C.albicansstrain-specific probe derived from repetitive sequence DNA). C.albicansobtained from the oral cavity of patients receiving cytotoxic chemotherapy was used as controls.ResultsUsing theH. capsulatumribosomal DNA probe, isolates were shown to members of many distinct classes of C.albicans.Forty-nine per cent (19 out of 39) of isolates were members of the same class; however, 46% (6 out of 13) of control C.albicansisolates were also members of this class. Further analysis of the class-restricted isolates from the HIV-infected patients using the C.albicansstrain-specific probe showed that these could be further separated into distinct strains.ConclusionsThese data indicate that strains of C.albicansthat cause oral candidiasis in HIV-positive individuals are not clonally restricted and are similar to those colonizing the oral cavity of other severely immunocompromised hosts. Most patients appear to be infected with unique strains of C.albicans.

ISSN:0269-9370    

出版商:OVID    

年代:1992

数据来源: OVID