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Query: UMLS:C0001175 (AIDS)
 120,706 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sera were obtained from 50 individuals infected with human immunodeficiency virus type 1 or from HIV-1-uninfected individuals before or after vaccination with recombinant gp160. These sera were evaluated for activity antagonistic to the cell-killing activity of the chimeric Pseudomonas exotoxin hybrid protein, sCD4-PE40. For these studies, Chinese hamster ovary (CHO) cells were transfected with a chimeric plasmid encoding the tat, rev, and envelope genes of HIV-1 and a cell line was selected for stable expression of the envelope glycoproteins at the cell surface (CHO-env). Cytotoxicity of sCD4-PE40 for CHO-env in the presence or absence of added human serum was quantitated spectrophometrically following enzymatic reduction of a tetrazolium bromide within the mitochondria of viable cells (MTT assay). Several HIV+ sera inhibited the cytotoxic activity of sCD4-PE40; the antagonist had properties consistent with those of immunoglobulins in that it was heat stable, absorbed by protein A, and reversible by increasing the concentration of sCD4-PE40. Of 15 HIV+ sera which strongly reacted with gp120, 11 (73%) also potently inhibited sCD4-PE40 cytotoxicity, and cytotoxicity was inhibited by sera from some HIV- individuals after, but not before, immunization with gp160. These data suggested a role for antibody to gp120 in the antagonistic activity. However, not all sera with antibody to gp120 antagonized sCD4-PE40 cytotoxicity and high levels of antagonist activity were frequently (40%) found in HIV+ sera lacking immunoblot-detectable antibody to gp120, or antibody to either CD4 or PE40. Grouping of the HIV+ sera according to the patients' absolute number of CD4+ cells revealed that the degree of inhibition of sCD4-PE40 cytotoxicity approached a Gaussian distribution, suggesting that persons with CD4+ cell counts between 200 and 700/mm3 may be more likely to possess significant levels of serum antagonist. This data have implications for the clinical development of sCD4-PE40 or other sCD4-based therapeutics in the management of HIV-1 infection.
AIDS Res Hum Retroviruses 1991 Sep
PMID:Soluble CD4-PE40 is cytotoxic for a transfected mammalian cell line stably expressing the envelope protein of human immunodeficiency virus (HIV-1), and cytotoxicity is variably inhibited by the sera of HIV-1-infected patients. 174 81

Retroviral envelope glycoproteins interact with cell receptors and are targets for antiviral immune responses in infected hosts. Macaque simian immunodeficiency virus (SIVmac) is a T-lymphocytopathic lentivirus which causes an AIDS-like disease in rhesus macaques. The envelope gene of SIVmac encodes a precursor glycoprotein (gp160) which is cleaved into an external domain (gp130) and a transmembrane domain (gp32). To investigate the functional and immunological properties of the SIV external envelope glycoprotein, we have used genetically engineered mammalian cells to produce recombinant gp130 (rgp130). The rgp130 has the appropriate molecular weight, is glycosylated, and has native conformation as determined by binding to the cell receptor for SIV, the CD4 antigen. Rhesus macaques immunized with purified rgp130 formulated in muramyl dipeptide adjuvant generated high titers of antienvelope antibodies. Antibodies from these macaques were tested for in vitro virus neutralization; very low or undetectable levels of neutralization were observed. In contrast, neutralizing antibodies were readily detected in sera from goats immunized with rgp130. With respect to cell-mediated immunity, proliferative responses to rgp130 were demonstrated in peripheral blood monocyte cells (PBMC) from macaques immunized with the recombinant glycoprotein as well as in PBMC from SIV-infected animals. These results show that rgp130 is functional and immunogenic; the potential of rgp130 for protective immunization remains to be determined.
AIDS Res Hum Retroviruses 1991 Nov
PMID:Functional and immunological characterization of SIV envelope glycoprotein produced in genetically engineered mammalian cells. 176 Feb 29

Immunosorbents specifically binding native (gp160, gp120, gp41) and recombinant env proteins and HIV-I virions were synthesized on the basis of Sepharose 4B and Silica with immobilized ligands such as gamma-fraction of rabbit antiserum to HIV-I proteins and purified antibodies to env proteins of HIV-I. The possibility was shown of selective extraction of HIV-I virions and individual HIV proteins both in vitro and in vivo. The titer of virus antigens (in ELISA) after perfusion via an immunosorbent of patterns with a high content of virions and HIV-I proteins was 8 times as low as the starting titer (after perfusion via the control sorbent it was 2-fold decreased). Extracorporeal immunosorption in animals after intravenous injection of recombinant env protein permitted the latter's titer to be 5 times lower. After perfusion via the control sorbent the titer dropped by at least 20% as compared with the starting titer. The possibility of using immunosorption in multimodality therapy of AIDS is under discussion.
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PMID:[Immunosorption of individual HIV proteins and virions]. 176 81

Anti-human immunodeficiency virus type 1 (Anti-HIV-1) antibody response was compared in four groups of mice following inoculation with HIV-1 gp160, with live recombinant vaccinia virus expressing HIV-1 envelope glycoproteins, or with both immunogens in alternate orders for primary or secondary immunizations. Both subunit and recombinant virus immunogens induced similar levels of antibody response following primary immunization. However, after secondary immunization, mice primed with live recombinant virus and then boosted with subunit gp160 immunogen showed significantly higher antibody response than those in the other three groups. Neutralizing antibodies were generated only in this group of mice and were shown to neutralize both the homologous virus (BRU) and a divergent isolate (SF2) of HIV-1. On the other hand, their reactivities to peptide sequences from the principal neutralizing determinant (PND) of gp120 were limited to the BRU isolate, not SF2 or MN, indicating that the cross-neutralizing activities were directed against determinants other than the linear epitope(s) within the PND. These results also indicate that combined immunization by priming with liver recombinant virus and boosting with subunit immunogen may be more effective than immunization by either immunogen alone.
AIDS Res Hum Retroviruses 1991 Jul
PMID:Neutralizing antibodies against HIV-1 BRU and SF2 isolates generated in mice immunized with recombinant vaccinia virus expressing HIV-1 (BRU) envelope glycoproteins and boosted with homologous gp160. 176 63

Gp160 expressed in vaccinia and produced in vero cells was integrated into iscoms. Gp160 iscoms elicited a high serum antibody response in mice, and after two immunizations a ceiling was reached. The serum antibody response was dissected by the use of defined recombinant DNA products, representing different regions of the gp160 molecule. High antibody titers to the peptid RP135 (a.a. 296-332) correlated with induction of neutralizing serum antibodies. In some animals, gp160 (IIIB) iscoms elicited cross-neutralizing antibodies that also neutralized the distantly related RF isolate.
AIDS Res Hum Retroviruses 1991 Jul
PMID:Cross-neutralizing antibodies to HIV-1 in mice after immunization with gp160 iscoms. Dissection of the immune response. 176 64

Healthy, human immunodeficiency virus seronegative (HIV-) volunteers were multiply immunized with a recombinant gp160 (rgp160) candidate acquired immunodeficiency syndrome (AIDS) vaccine. Peripheral blood lymphocytes from volunteers immunized with 40 micrograms or with 80 micrograms (two volunteers per group) of rgp160, as well as from control donors, were tested for T helper (Th) cell function either prior to immunization, 8 to 12 months after the third immunization, or 2 to 5 months after the fourth immunization. The Th cell functional tests included antigen-induced in vitro interleukin 2 (IL 2) production and proliferation in response to influenza A virus (FLU) and to four synthetic peptides of HIV gp120 and gp160, previously demonstrated to be recognized by T cells from HIV naturally infected patients. Our results demonstrate the following: (a) immunization of HIV- individuals with rgp160 results in IL 2 production and T cell proliferation in response to HIV determinants; (b) boosting with rgp160 enhances Th function; (c) HIV-specific Th function is up to 100-fold greater in the multiply immunized volunteers than that observed in asymptomatic, HIV-infected individuals; and (d) multiple immunization with rgp160 does not impair Th function to a non-HIV antigen such as influenza A virus. These results indicate that immunization of uninfected individuals with an HIV subunit vaccine results in much stronger Th cell immunity than does natural infection and suggests that vaccination against HIV may be possible.
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PMID:Immunization with subunit human immunodeficiency virus vaccine generates stronger T helper cell immunity than natural infection. 184 91

The significance of understanding the vertical transmission of HIV lies in the 78% of women's AIDS cases (1991) of sexually active women who may transmit the infection to their offspring. 2% of children in the US and 5-25% of children in developing countries are HIV infected. The current rates of maternal-fetal transmission average 25-30%. Interrupting this mode of passage would provide protection for children. The Van de Perre study on postnatal transmission by breast feeding is discussed in order to the timing of HIV infection and the relationship to infant risk of infection. Postnatal infection of infants suggests that the risk is enhanced during the primary infection of the mother. It is pointed out that transient but large elevations in plasma virus titers have been observed during primary infection of homosexual men, before anti-p24 and anti-gp160 antibodies appear. These plasma titers may increase the efficiency of vertical transmission. It is also possible that the absence of neutralizing or nonneutralizing antibodies may enhance transmission. The frequency of new infections is estimated by Van de Perre in the rate of seroconversion in Rwandan women as 4.7-7.3%/year. The US rate is .6-.8/1000/year for all adults and adolescents. Pregnancy can occur after primary HIV infection or at the onset when plasma titers are high and antibody levels are low. It is reported that the rate of transmission may be highest when mothers are in a more advanced disease state. Another factor affecting transmission is the presence or absence of maternal antibodies. Lower HIV transmission may be related to the presence of epitopes on the hypervariable V3 loop of HIV gp120 or the principal neutralizing domain. Although HIV virus has been identified in fetal tissues after 8-15 weeks gestation, there is reason to believe that the greatest transmission is intrapartum because maternal blood may be ingested or there is maternal-fetal transfusion during labor and delivery. New York studies have suggested that 50% of infected infants of known seropositive women will be positive by the polymerase chain reaction by 3 months of age and 50% by 3-6 months of age. It is likely that the delay is due to infection late in gestation.
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PMID:In the vertical transmission of HIV, timing may be everything. 181 50

CV-1 cells were infected with two recombinant vaccinia viruses carrying the gag gene with deletion of 231 bp from 3' terminus (strain vC5) and env gene (strain vE234L) of human immunodeficiency virus type 1 (HIV-1). Both recombinant proteins synthesized in the cells (p50gag and gp160/120env) were localized predominantly in cell membranes; however, some amount of p50 was found in cell nuclei. Thin-section immunoelectron microscopy showed accumulation of viruslike particles undistinguished from immature HIV-1 virions in the culture medium of the cells infected with vC5. The similar particles containing gag and env proteins were produced into the culture medium when the cells were coinfected with vC5 and vE234L strains. The particles contained heterogeneous cellular RNA, but no virus-specific RNA as shown by Northern blot hybridization. Immunization of the rabbits with purified viruslike particles produced virus-specific antibodies against gag and env proteins. The titer of antibodies was significantly higher than after immunization with cell lysate or recombinant proteins purified from the infected cells. Highly immunogenic HIV-1-like particles containing gag and env proteins but no virus-specific RNA are good candidates for potential vaccine.
AIDS Res Hum Retroviruses 1991 Jan
PMID:Highly immunogenic human immunodeficiency viruslike particles are produced by recombinant vaccinia virus-infected cells. 190 21

Recombinant retroviral vectors can efficiently transduce and express foreign genes in mammalian cells. We have examined the utility of retroviral vector-mediated gene transfer to deliver genes which encode human immunodeficiency virus type I (HIV) antigens capable of stimulating specific immune responses. Murine fibroblast cell lines were transduced with a nonreplicating murine retroviral vector carrying the gene encoding the HIV-IIIB envelope protein and were shown to express the gp160/120 protein. Mice immunized with syngeneic vector-transduced cells developed CD8+, class I major histocompatibility complex (MHC)-restricted cytotoxic T lymphocytes (CTL) specific for targets expressing the HIV envelope protein. The CTL also exhibited lytic activity on target cells coated with synthetic peptides derived from the gp120 V3 hypervariable region of both the HIV-IIIB and HIV(MN) isolates. Following adoptive transfer in a murine tumor model, these CTL were shown to be effective in vivo by their ability to eliminate established tumor cells expressing the HIV protein. Vector-transduced syngeneic cells were also capable of eliciting HIV envelope-specific antibody responses in immunized mice. Sera obtained from these mice were found to bind to the HIV-IIIB gp160 protein as well as a peptide-defined neutralizing antibody epitope contained within the V3 domain of gp120. These sera exhibited virus-neutralizing activity in that they markedly reduced the ability of HIV to infect and form syncytia of a human T-cell line. This is the first demonstration that cells transduced with a retroviral vector encoding the HIV-IIIB envelope protein are capable of inducing effective HIV-specific cellular and humoral immune responses in mice.
AIDS Res Hum Retroviruses 1991 Aug
PMID:Induction of HIV-specific CTL and antibody responses in mice using retroviral vector-transduced cells. 193 Dec 34

HIV-1 neutralizing activity was demonstrated in serum and 200-fold concentrated urine from individuals who were HIV-1 antibody positive in both their serum and urine, including AIDS-KS, AIDS-OI, ARC, and asymptomatic patients. Virus neutralization activity was detected in 23 of 56 (41.1%) of the serum samples and in 19 of 56 (33.9%) of the urine samples tested, with titers ranging from 1:8 to 1:256 and 1:1 to 1:4, respectively. The highest frequency of HIV-1 neutralizing activity (87.5%) and the highest mean neutralization titers (1:65) were found in the ARC patients. A high prevalence of p24 antigen in serum and low numbers of T4-lymphocytes correlated with a low frequency of neutralizing activity in either serum or urine in the infected individuals. HIV-1 neutralizing activity in the urine was shown to be due to immunoglobulins using a Sephadex G-100 filtration gel. All 19 urine samples with neutralizing activity contained antibodies reactive with envelope glycoproteins gp160, gp120, and gp41 by Western blot, similar to that seen with serum. The frequency of HIV-1 neutralizing activity in the urine concentrates was generally associated with high titers of neutralizing antibody in the corresponding serum. These findings suggest that HIV-1 neutralizing antibodies are lost in the urine by an as yet unknown mechanism.
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PMID:HIV-1 neutralizing antibodies in urine from seropositive individuals. 196 94


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