ISSN:0889-2229    

DOI:10.1089/aid.1995.11.1

年代:1995

数据来源: MAL

摘要:

Detailed studies of HIV viral load and phenotype were performed on sequentially cryopreserved peripheral blood mononuclear cells (PBMCs) from eight infected individuals followed in the Los Angeles Multicenter AIDS Cohort Study. Three individuals remained clinically and immunologically stable over a 5- to 8-year period, three demonstrated precipitous and two gradual declines in CD4+T lymphocytes. Viral load in PBMCs was quantitated by limiting dilution culture and DNA PCR, while minimally passaged viral isolates were studied for their ability to induce syncytium formationin vitroand, when relevant, sensitivity to zidovudine (ZDV). Viral burden remained relatively low in those who remained clinically and immunologically stable, while increasing substantially in all five individuals who experienced a decline in CD4+T lymphocytes. Two subjects were noted to have a switch from non-syncytium-inducing (NSI) to syncytium-inducing (SI) isolates immediately preceding a precipitous decline in CD4+T lymphocytes, while the third individual who experienced such a decline and the two who had gradual declines did not develop SI isolates. Moreover, of the three subjects who experienced a decrease in CD4+T lymphocyte number and were given ZDV during the study period, none were noted to develop resistance to this agent. In summary, the virology in clinically and immunologically stable individuals was characterized by relatively low viral burden in PBMCs and a predominance of NSI isolates. In contrast, while there was consistently an inverse relationship between viral load and CD4+T lymphocyte number in those who experienced an immunological decline, a phenotypic switch from NSI to SI isolates occurred in only two of the five subjects who demonstrated such a decline, and no ZDV-resistant isolates were detected in any of the treated individuals.

ISSN:0889-2229    

DOI:10.1089/aid.1995.11.3

年代:1995

数据来源: MAL

摘要:

As thymocyte infection may represent one of the mechanisms responsible for CD4+T lymphocyte depletion in HIV-1-infected individuals, we studied the occurrence of HIV-1 infection in the thymusin vivo. Thymus (THYPD) and peripheral blood (PBLPD) primary viral isolates were obtained from an HIV-1-infected patient; restriction pattern analysis revealed the presence of a viral variant (THY) in the thymus isolate, from which biological viral clones containing this variant were obtained by limiting dilution infection of Molt-3 cells. The biological phenotype of the viral isolates and THY clones was studied in different cell lines and primary cultures. PBLPD, THYPD, and THY clones could efficiently infect T cell lines; the thymic variant showed a higher cytopathic activity in T cell lines, and a higher replication capacity in both unfractionated and CD4+CD8+-enriched primary thymocytes. Sequence analysis of the viral population patternsin vivoconfirmed the presence of the THY variant in the thymic compartment, and revealed that the degree of V3 loop heterogeneity was higher in the thymocytes of the patient than in the peripheral blood lymphocytes. In addition to confirming thymocyte infectionin vivo, our data also indicate that a differential distribution of viral variants may occur among different body compartments in a single individual; the emergence of cytopathic and tissue-specific variants in the thymus may play a relevant role in the pathogenesis of HIV-1 disease.

ISSN:0889-2229    

DOI:10.1089/aid.1995.11.11

年代:1995

数据来源: MAL

摘要:

During HIV infection, individuals experience multiorgan disorders such as adenopathy, splenomegaly, and lung and brain diseases. There is an increasing body of evidence that the HIVtrans-activatingtatgene product possesses multiple activities. First, it can activate several cellular genes; second, in its extracellular soluble form, it plays the role of growth factor in some cells such as Kaposi's sarcoma cells. Thus, we introduced the HIVtatgene, under the control of the cellular proteolipoprotein promoter, into the germline of mice and demonstrate that, when expressed, thetatgene product induces lymphoid hyperplasia in spleen, lymph nodes, and lung, as is observed in AIDS patients, but not in the brain or testes. Our findings indicate that HIV, through some of its genes, directly participates in the pathogenesis of AIDS.

ISSN:0889-2229    

DOI:10.1089/aid.1995.11.21

年代:1995

数据来源: MAL

摘要:

Human immunodeficiency virus (HIV-1)tat, atrans-activator of the HIV long terminal repeat, is essential for HIV replication and causes inhibition of antigen-mediated T cell proliferation. To understand the mechanism of inhibition of T cell proliferation, we have investigated the regulation of IL-2 production and its receptor expression on a human CD4+T lymphoid cell line (H9) transfected with HIV-1tatgene. When cells were activated by mitogens, as compared to control cells, a significant decrease in both IL-2 mRNA and protein was observed intat-transfected cells. Similarly, mitogen-induced IL-2Rα and IL-2Rβ mRNA and surface expression of IL-2Rα and IL-2Rβ chains were also significantly decreased intat-transfected cells compared to control cells. Only IL-2 receptor density was decreased; the affinity of the ligand for the receptor appeared to be unchanged. In contrast to our previous studies with B-lymphoblastoid cell line (Puri RK and Aggarwal BB: Cancer Res 1992;52:3787–3790), IL-4R expression was unaltered by HIVtattransfection in the H9 T cell line, indicating a cell type-specific phenomenon. Owing to the central role of IL-2 in immunoregulation, our data suggest that immunosuppressive effects of HIV-1tatmay be mediated at least in part through the inhibition of both IL-2 production and IL-2 receptor expre

ISSN:0889-2229    

DOI:10.1089/aid.1995.11.31

年代:1995

数据来源: MAL

摘要:

It has been previously shownin vitroandin vivothat the human immunodeficiency virus type 1 can be dramatically enhanced by certain heterologous viral, chemical, and physical (ultraviolet irradiation) agents. A common denominator shared by these agents is their ability to cause stress responses in cells. To analyze if a similar effect could occur by X irradiations, we tested thein vitroeffect of X rays on HIV LTR-directed gene expression. The results demonstrate that the HIV-1 LTR is activated by X irradiation in a dose- and time-dependent manner, in all cell types tested, including epitheloid, fibroblast, and lymphoid cell lines. This study raises the possibility that exposure of AIDS patients to ionizing radiation (e.g., during treatment of epidemic Kaposi's sarcoma) could play a role in the activation of HIV-1in vivo.

ISSN:0889-2229    

DOI:10.1089/aid.1995.11.41

年代:1995

数据来源: MAL

摘要:

The partially CD4-expressing T cell clone, Vpr-1, which carries a latentvpr-defective HIV-1 genome and expresses HIV-1 Nef protein only, was permissive to superinfection by HIV-1. Superinfection of Vpr-1 withvif- orvpu-defective mutants, which were noncytopathic, reactivated thevpr-defective virus and led to homologous recombination and cytopathogenesis. The data provide an experimental model for homologous recombination being an important mechanism whereby HIV-1 acquires genetic heterogeneity, and when occurring among defective virusin vivobestows novel biological activities and virulence.

ISSN:0889-2229    

DOI:10.1089/aid.1995.11.45

年代:1995

数据来源: MAL

摘要:

Assembly and budding of retroviruses is believed to involve a complex interaction of envelope and capsid proteins at the host cell membrane. The nature of these interactions is, however, incompletely understood. Studies of the topography of the surface of HIV-1 have shown that the envelope glycoprotein projections (knobs) are arranged in aT= 7 levo rotational symmetry. Similarly, an icosahedral structure has been suggested for the pl7 matrix of HIV-1. In an effort to investigate whether there is a structural interaction between these molecules, virions whose maturation was blocked by an inhibitor of HIV protease were studied using cytochemistry, morphometry, and 2D fast Fourier transform image enhancement. Analysis of the relationship between core morphology and the topographic distribution of envelope glycoprotein projections on HIV-1 provided structural evidence of an interaction between Env and Gag proteins. Furthermore, image enhancement revealed a periodic substructure in the Pr55gagplaque. Taken together, the data suggest an interaction between Pr55gagand the gpl20-gp41 complex during assembly and budding of HIV-1. This interaction may, in part, contribute to determining the amount of Env glycoprotein that will be incorporated into a virion, and therefore play a role in the biology of HIV-1.

ISSN:0889-2229    

DOI:10.1089/aid.1995.11.55

年代:1995

数据来源: MAL

摘要:

The human immunodeficiency virus type 2 (HIV-2) Nef protein expressed inEscherichia coliforms highly stable homooligomeric complexesin vitro. Similarly, the native protein synthesized in the persistently infected H9 T cell line also forms stable homooligomersin vivo. To determine whether homooligomer formation is mediated by the leucine zipper-type sequence located in the middle region of the protein, site-directed mutagenesis was used to introduce double and triple point mutations at heptad leucine positions L1, L2, and L4 within the HIV-2NIHZNef protein sequence. Here, we show that substitution of a serine residue for the L1 (residue 108) and L2 (residue 115) heptad leucines, and a glutamine residue for the L4 (residue 129) heptad leucine, did not prevent Nef homooligomer formationin vitro. However, a more drastic substitution of α-helix-breaking proline residue for the L2 and L4 heptad leucines significantly abrogated ability of the protein to form stable homooligomers. In addition, because significantly higher levels of the Nef oligomers were consistently observed under the nonreducing SDS-PAGE condition, site-specific mutagenesis was also used to examine the role of cysteine residues in generating disulfide-linked Nef dimersin vitro. Here, we also show that single cysteine-to-glycine substitutions at positions 28, 32, or 55 drastically reduced covalent Nef dimer formation and thermal stability of the Nef proteinin vitro. Therefore, these results demonstrate that the leucine zipper-type motif in the HIV-2 Nef protein mediates stable homooligomer formationin vitro, and also establish a role for covalent disulfide bonds in the formation of linked Nef dimers and thermal stability of the monomer Nefin vitro

ISSN:0889-2229    

DOI:10.1089/aid.1995.11.65

年代:1995

数据来源: MAL

摘要:

Proteolytic processing of the human immunodeficiency virus type 1 (HIV-1) envelope (Env) precursor glycoprotein (gp 160) to produce the mature gp120 and gp41 proteins is required for virus infection and virus-induced cell fusion. It has also been suggested that cleavage of gp120 at the immunodominant V3 loop region is required for virus-to-cell and cell-to-cell fusion. In this investigation we have studied the proteolytic processing of the HIV-1 Env in cells of various origins (human, monkey, and mouse) infected with a vaccinia virus recombinant expressing the entire gp160 protein (VV-env-1). We have observed that in murine Ltk(-) cells, in addition to the proteolytic cleavage of gp160 at the gp 120/gp41 site, there is also extensive intracellular proteolytic processing of gp160 at the V3 loop and at a novel site located at the C terminus of gp41. Similar proteolytic processing of the Env precursor was observed after treatment of extracts of VV-env-1-infected monkey cells with thrombin, a trypsin-like protease that has been shown to cleave the gp120 at the V3 loop. Our findings suggest that murine Ltk(-) cells could be a good model system for structural studies of Env with different HIV isolates and in searches for proteinase inhibitors that could prevent HIV-1 infection of susceptible cells by blocking proteolysis of Env.

ISSN:0889-2229    

DOI:10.1089/aid.1995.11.81

年代:1995

数据来源: MAL