ISSN:0889-2229    

DOI:10.1089/aid.1994.10.1

年代:1994

数据来源: MAL

摘要:

Current approaches to the prevention and control of AIDS by vaccines and by chemotherapy have failed to provide satisfactory solutions to this important medical problem and have failed, in addition, to provide definitive guidelines for future research endeavor. Vaccine research must and will continue but it is possible that a safe and effective vaccine may never be developed and it may be timely to explore, in addition, alternative means for immunological intervention in AIDS. Both immunoprophylactic and immunotherapeutic efforts might be assisted by manipulating the T helper 1 (Th1) and T helper 2 (Th2) subsets of CD4+T helper cells, which is therefore worthy of exploration. Selective control of immune response by the two T helper subsets is by release of different cytokines that promote either cellular or humoral immunity, the latter of which may be associated with inappropriate immune responses and with immune dysfunction. Discovery of the Th1 and Th2 subsets and definition of the cytokines they release provide a new avenue toward possible development of a safe and effective vaccine and an approach, in addition, to correction of immune dysfunction by selective cytokine administration or by cytokine ablation by antagonists or antibodies. AIDS pathogenesis and immune dysfunction are complex and understanding them may be overwhelmed by an excess of possibilities. Simplification of the endeavor might benefit from comparative studies of the pathogenesis of measles, in which there also is immune deficiency but usually with spontaneous viral clearance, reversal of immune dysfunction, and total recovery. In addition, measles presents as a single disease and is caused by an antigenically stable virus. Identification of the process whereby measles immunodeficiency is spontaneously reversed might be of importance in attempting to devise means for similar reversal in AIDS.

ISSN:0889-2229    

DOI:10.1089/aid.1994.10.3

年代:1994

数据来源: MAL

摘要:

B lymphocytes from tonsillar tissue of an asymptomatic HIV-1-seropositive subject were transformed with Epstein-Barr virus (EBV) and tested for the production of HIV-1-specific antibodies by ELISA, using purified HIV-1SF2. 2F11, a monoclonal antibody derived from a transformed line, is of the IgG1subclass and recognizes an epitope in the conserved region of the envelope transmembrane glycoprotein gp41, which is expressed on the surface of HIV-infected T cells. The antibody does not mediate the lysis of infected T cells in antibody-dependent cellular cytotoxicity (ADCC) assays and does not neutralize the infectivity of HIV-1SF2or the homologous isolate HIV-1TT2. 2F11 appears to be the first anti-gp41 human monoclonal antibody that enhances the infectivity of an HIV-1 strain (i.e., SF128A) in the absence of complement.

ISSN:0889-2229    

DOI:10.1089/aid.1994.10.13

年代:1994

数据来源: MAL

摘要:

Cytotoxic T cell determinants should be an important component of an anti-human immunodeficiency virus (HIV) vaccine. The epitopes of proteins can be defined with short synthetic peptides for class I-restricted CTLs. An immunodominant CTL epitope from the HIV-1 IIIBenvelope protein gp160 comprising 15 amino acids (residues 315-329: RIQRGPGRAFVTIGK) (P18IIIB) has been identified that is recognized by class I MHC molecule H-2d-restricted murine CD8+CTLs. We have investigated the epitope specificity of anti-HIV-1 CTLs in immunized individuals and we found that the CTL response was restricted by more than one class I MHC molecule, including HLA-A2 and HLA-A3. In the present work, we also show that the response against P18IIIBpeptide is restricted by the HLA-A11 molecule in an individual immunized by vaccinia virus expressing gp160 protein. This peptide could thus be recognized in association with different HLA class I allotypes. This work has implications for vaccine strategies, using the P18 peptide.

ISSN:0889-2229    

DOI:10.1089/aid.1994.10.19

年代:1994

数据来源: MAL

摘要:

A battery of assay systems was used to profile both humoral and cell-mediated immune responses induced by immunization with candidate vaccines consisting of recombinant simian immunodeficiency virus (SIV) glycoproteins rgp110(nondenatured) with SAF-M adjuvant (gp110 + SAF-M) or rgp140 (denatured) with Freund's adjuvant (gp140 + FA). All of the monkeys became infected after intravenous challenge. However, 16 days following infection, viral antigenemia was reduced in both groups of vaccinates compared to controls. After 23 days antigenemia in the gp110 + SAF-M group remained at the same level as on day 16, whereas antigenemia in the gp140 + FA group was significantly reduced further than the level observed on day 16. Both vaccines induced blastogenic responses in PBMC cultures stimulated with rgp140, which decreased after repeated immunizations. Both vaccines induced high ELISA titers of IgG antibody against rgp140 that were equivalent to the titers in asymptomatic long-term survivors (LTSs). gp110 ± SAF-M induced high titers of neutralizing antibody. In contrast, gp140 + FA failed to induce neutralizing antibody, suggesting that the natural conformation of the antigen may be essential for the induction of neutralizing antibody. High titers of antibodies capable of complement-mediated cytolysis (ACC) were induced by gp110 + SAF-M, whereas minimal ACC antibodies were induced by gp140 + FA. In spite of high titers of antibodies by ELISA, neither gp110 + SAF-M nor gp140 + FA vaccines induced detectable levels of antibody capable of antibody dependent cell-mediated cytolysis (ADCC). Detectable amounts of MHC class I-restricted, CD8+cytotoxic T lymphocytes (CTLs) were not induced in immunized monkeys before challenge. After challenge and infection, antibody responses to glycoprotein (detected by ELISA and ACC) as well as glycoprotein-specific CTLs were induced in gp140 + FA vaccinates at levels higher than in nonimmunized control animals, indicating a priming effect by gp140 + FA immunization. No priming effect for ADCC antibody induction was observed in monkeys vaccinated with either gp110 + SAF-M or gp140 + FA. Rhesus monkey groups immunized with two different SIV envelope vaccines differed regarding potentially protective humoral and cell-mediated immune responses. The physical state of the immunogens, the type of adjuvant used, and/or the immunization protocol apparently affected these responses in both a qualitative and quantitative manner

ISSN:0889-2229    

DOI:10.1089/aid.1994.10.27

年代:1994

数据来源: MAL

摘要:

The drug sensitivities of human immunodeficiency virus type 1 (HIV-1) isolates from a group of four untreated and seven TIBO R82913-treated patients were determined in a reverse transcriptase (RT) assay. Five of the treated patients harbored HIV-1 isolates with R82913 sensitivity comparable to that of the isolates of untreated patients, ranging from almost 2-fold higher sensitivity to 13-fold lower sensitivity than that of recombinant p66 RT. From one of the seven treated patients, an HIV-1 strain with a 20-fold reduced sensitivity to R82913 could be isolated; and from another patient, a strain with 100-fold reduced sensitivity (resistance) was isolated. The drug-resistant strain in this patient emerged after 3 weeks of treatment and was due to the Y188L mutation in its RT. On passaging the virus in cord blood lymphocytes, but not in CEM cells, the resistant virus was lost in favor of a different HIV-1 strain harboring the wild-type Y188 with a sensitivity to R82913 comparable to that of wild-type p66 RT. In several HIV-1 isolates (from treated and untreated patients), some HIV-2- and CIVgab-specific amino acids were found. One of these substitutions, that is, I/V179D (from an untreated patient), conferred a sevenfold reduced RT sensitivity to R82913.

ISSN:0889-2229    

DOI:10.1089/aid.1994.10.39

年代:1994

数据来源: MAL

摘要:

Replication of the human immunodeficiency virus depends on the expression of its regulatory genes. We have constructed three plasmids, based on the retrovirus vector LXSN, that contain thetat, rev, andenv(pLTRESN), therevandenv(pLRESN), and thenef(pLnefSN) genes of HIV-1. In a two-step virus rescue protocol, during which introns are removed from the DNA fragments inserted into pLXSN, these plasmids were used to establish amphotropic retrovirus vector producer lines for the transfer oftat(LtatSN),rev(LrevSN), andnef(LnefSN). These vectors have titers greater or equal to 106CFU/ml and efficiently transduced each of these genes into a variety of human and murine cell lines. Representative populations of cells constitutively expressing thetatandrevgenes were obtained. Cell lines transduced with LtatSN were able to trans-activate an HIV-LTRCAT construct, indicating the presence of a functional Tat protein. Similarly, cells transduced with LrevSN were able to rescue arev-HIV-1 provirus, indicating the presence of a functional Rev. We also used LnefSN to obtain clones of cells expressing Nef. Our results indicate that these retrovirus vectors are useful reagents for the efficient transfer of functional Tat, Rev, and Nef and for the establishment of cell lines constitutively expressing these genes.

ISSN:0889-2229    

DOI:10.1089/aid.1994.10.47

年代:1994

数据来源: MAL

摘要:

During an acute human immunodeficiency virus (HIV) infectionin vitro, different forms of unintegrated viral DNA accumulate in target cells. They include linear full-length HIV DNA molecules, which are the precursors of the integrated provirus, and two types of circular molecules (with one or two LTRs), whose role and mode of formation are not fully understood. To evaluate the intracellular fate of HIV unintegrated DNA, and to follow the formation of the two types of circular DNA molecules, the nuclear transport of viral DNA, and its integration in host cell DNA, we have designed a "DNA chase" assay. This assay is based on cocultivation of persistently HIV-1-infected H9 cells with uninfected MT4, allowing rapid accumulation of viral DNA, which is then blocked by addition of AZT. In this highly efficient, synchronous, one-step cycle infection system, HIV linear DNA can be detected on Southern blots as early as 4 hr after the start of the coculture. Subsequently, viral DNA that had been synthesized before the addition of AZT could be "chased," establishing that almost all linear DNA molecules are rapidly transported to the nucleus, where they are either processed into the two types of circles or integrated. We could estimate that from the number of viral DNA molecules synthesized in 6 hr in this system, at least a third will become integrated and another third will circularize within 24 hr.

ISSN:0889-2229    

DOI:10.1089/aid.1994.10.53

年代:1994

数据来源: MAL

摘要:

Interacting dendritic cells and helper CD4+lymphocytes form a microenvironment that is permissive for HIV-1 replication. The virus need only be pulsed initially onto the dendritic cells, which then transfer HIV-1 to the lymphocytes that are responding to presented antigens or superantigens. We have pursued underlying mechanisms in this system, because it provides a model for the infection of antigen-reactive, primary T cells. Pulsing the T cells with HIV-1 results in much less of a subsequent infection than does pulsing the dendritic cells. The latter pulse occurs effectively in the presence of AZT. Direct examination of the interacting dendritic cells and T cells reveals extensive production of p24 by many of the lymphocytes, including syncytia. The majority of the responding T cells die during the coculture. Apoptosis accounts for much of this death as revealed byin situnick translation assays for DNA endonucleolysis, and hypodiploid profiles on staining with DNA-binding dyes. Therefore the microenvironment that is generated between antigen-presenting dendritic cells and T cells reveals the cytopathic potential of HIV-1, because there is such extensive and rapid death by apoptosis of antigen-reactive T cells.

ISSN:0889-2229    

DOI:10.1089/aid.1994.10.61

年代:1994

数据来源: MAL

摘要:

SIVsmmPBJ 1.9 is an extremely virulent clone of the simian immunodeficiency virus SIVsmmPBj 14 that causes an acute lethal disease in pigtail macaques, with death occurring 6 to 8 days after infection. The disease is characterized by bloody mucoid diarrhea, lymphoid hyperplasia, and giant cell pneumonia. We have developed anin vitromodel for the production of multinucleated giant cells (MGCs) in which peripheral blood monocytes rapidly fuse to form MGCs when cultured in lymphocyte-conditioned medium and antibody against class II MHC. We have tested the effect of SIVsmmPBj on monocytes in our MGC model system. Peripheral blood mononuclear cells (PBMCs) from normal healthy human subjects, when cultured in the presence of anti-class II MHC monoclonal antibody and SIVsmmPBj 1.9, but not either alone, resulted in the formation of MGCs within 4 days. Experiments using Transwell chambers indicated that such MGCs are formed by fusion of monocytes, not by virus-induced fusion of lymphocytes. SIVsmmPBj 1.9 is unique in inducing MGC formation in that other SIV and HIV isolates do not induce MGCs. Whereas SIVsmmPBj 1.9 grown in PBMCs was a potent inducer of MGCs in the presence of anti-class II MHC antibody, SIVsmmPBj 1.9 grown in CEMx174 failed to do so. Antibodies against IFN-γ and TNF-α significantly inhibited SIVsmmPBj/anti-class H-induced formation of MGCs. These results indicate that cytokines released in response to SIVsmmPBj 1.9, in conjunction with antibodies to class II MHC, caused fusion of monocyte

ISSN:0889-2229    

DOI:10.1089/aid.1994.10.73

年代:1994

数据来源: MAL