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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have developed a series of murine monoclonal antibodies to a region of the 120 kD envelope glycoprotein (gp120) of human immunodeficiency virus type 1 (HIV-1). This region has previously been implicated as a site for virus neutralization by antisera raised to recombinant proteins and by antibodies made to full-length gp120 purified from virus. The antigen employed was a synthetic peptide containing 15 amino acids, representing amino acid residues 308-322, RIQRGPGRAFVTIGK, of env gp120 (HTLV-IIIB isolate). Five of the monoclonal antibodies raised to this antigen have reactivity with gp120 from divergent strains of HIV-1 in Western blot assays. The two of these five which were tested with live cells infected with the divergent HIV-1 isolates IIIB, MN, and RF were specifically reactive by fluorescence analyses with cells infected with the MN and IIIB isolates. Four of the five monoclonal antibodies blocked the fusion of IIIB-infected cells with uninfected MOLT-4 target cells. The monoclonal antibody most reactive with MN-infected cells by fluorescence, #5025A, blocked the fusion of MN-infected cells with uninfected MOLT-4 cells. Four of the five monoclonal antibodies neutralized the IIIB isolate of HIV-1 in vitro, but none neutralized the MN or RF isolates at the levels of antibody tested (less than or equal to 50 micrograms/ml). Taken together these data indicate that monoclonal antibodies to the immunodominant neutralizing domain of HIV-1 gp120 display different levels of group reactivity depending on the assay system being examined.
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PMID:HIV-1 neutralizing monoclonal antibodies induced by a synthetic peptide. 170 1

LDV/7, H9, and MOLT-4, three cell lines infectible by human immunodeficiency virus were incubated with dimethyl sulfoxide, an inducer of cell differentiation. It was shown that this is a powerful inhibitor of viral production, but its effect is transient: viral production resumes when the compound is removed from the culture medium. It does not inactivate the virus, and it fails to prevent viral infection or to inhibit expression of p24 on the surface of the infected cells.
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PMID:Dimethyl sulfoxide inhibits human immunodeficiency virus production in vitro. 170 66

Biliverdin (BV) is a bile pigment having anti-allergic properties. We examined the effect of BV on human immunodeficiency virus type 1 (HIV-1) in vitro. BV completely inhibited the cytopathic effect of HIV-1 in MT-4 cells at concentrations of 22.2 micrograms/ml or more. This inhibitory effect was also observed when BV was present during the adsorption period of HIV-1. However, BV was cytotoxic to MT-4 cells at concentrations above 800 micrograms/ml. At a concentration of 66.7 micrograms/ml, BV completely inhibited syncytia formation by HIV-infected and uninfected MOLT-4 cells. Moreover, after exposure of HIV-1 particles to BV for 2 h, the infectivity of the virus was reduced in a dose-dependent manner. It is speculated that the anti-HIV activity of BV is due to direct inactivation of virions and inhibition of virus binding to target cells.
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PMID:In vitro anti-human immunodeficiency virus type 1 activity of biliverdin, a bile pigment. 171 37

Complestatin, an anti-complement agent, was shown to be a potent inhibitor of human immunodeficiency virus type 1 (HIV-1) infection in vitro. It inhibited HIV-1-induced cytopathicity and HIV-1 antigen expression in MT-4 cells; the 50% effective doses for these effects were 2.2 and 1.5 micrograms/ml, respectively. No toxicity for MT-4 cells was observed at concentrations up to 400 micrograms/ml. In addition, the agent inhibited the focus formation in HT4-6C cells (CD4-positive HeLa cells); the concentration for 50% focus reduction was 0.9 microgram/ml. HIV-1-induced cell fusion in cocultures of MOLT-4 cells and MOLT-4/HTLV-IIIB were also blocked by complestatin (the concentration for 50% cell fusion inhibition, 0.9 microgram/ml). Complestatin had no ability to inhibit HIV-1 reverse transcriptase activity. When MT-4 cells were pretreated with complestatin for 2 hrs prior to the exposure to HIV-1, the HIV-1-induced cytopathicity was markedly inhibited, while pretreatment of HIV-1 with the agent did not affect the infection. These results suggest that complestatin primarily interacts with cells and inhibits viral adsorption to the cell surface as well as adsorption of infected cells to adjacent cells.
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PMID:Inhibition of human immunodeficiency virus type-1-induced syncytium formation and cytopathicity by complestatin. 171 91

The processing and secretion of the envelope glycoproteins of human immunodeficiency virus type 1 (HIV-1) were studied in chronically infected T cells and in primary macrophages treated with an antiviral antibiotic brefeldin A (BFA). BFA blocks the egress of proteins from the endoplasmic reticulum and has a profound effect on the structure of cis/medial Golgi. In MOLT-3 cells infected with the IIIB strain of HIV-1 (MOLT-3/IIIB), BFA inhibited the intracellular processing of gp160. The secretion of envelope proteins from these cells was significantly inhibited in the presence of BFA. The gag proteins, on the other hand, were processed and secreted normally. BFA also inhibited the proteolytic processing of gp160 in primary macrophages infected with HIV-1. The infectivity of virus pelleted from the medium of MOLT-3/IIIB cells treated with BFA was markedly lower than that obtained from untreated cells. These results demonstrate that the proteolytic processing of gp160 in HIV-1-infected cells takes place after the glycoprotein exists the endoplasmic reticulum and that the transport of glycoprotein to the cell surface is required for assembly of complete HIV-1 particles.
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PMID:Brefeldin A inhibits the processing and secretion of envelope glycoproteins of human immunodeficiency virus type 1. 171 46

We established seven hybridoma clones producing monoclonal antibodies (MAbs) against the envelope transmembrane protein (TMP) of a Ghanian isolate of human immunodeficiency virus type 2 (HIV-2[GH-1]) from mice immunized with the detergent-disrupted purified whole virus. The MAbs were found to react with 35 kilodalton (kD) TMP of the HIV-2[GH-1] virus in a Western blot assay (WB). Two of these MAbs recognized 135 kD proteins in addition to TMP in the lysate of HIV-2[GH-1]-infected cells. Two other MAbs cross-reacted with viral components corresponding to TMPs of HIV-2ROD and SIVMAC isolates in a Western blot. Results of competitive binding assay suggest that there are at least three epitopes on a TMP molecule of the HIV-2[GH-1] isolate. The MAbs did not inhibit syncytium formation between HIV-2[GH-1]-infected MOLT-4 cells and MOLT-4 clone 8 cells, nor virus infection to MOLT-4 clone 8 cells.
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PMID:Production and characterization of mouse monoclonal antibodies against the transmembrane protein of a human immunodeficiency virus type 2. 172 59

We isolated four monoclonal antibodies (MAbs), M38, M101, M104, and C33, which were capable of inhibiting syncytium formation induced in a human T-cell line, MOLT-4-#8, by coculture with human T-cell leukemia virus type 1 (HTLV-1)-positive human T-cell lines. The MAbs had, however, no inhibitory activity on syncytium formation induced in a human osteosarcoma line, HOS, by HTLV-1-positive T-cell lines. They also did not inhibit syncytium formation induced in MOLT-4-#8 by human immunodeficiency virus type 1-positive MOLT-4. All MAbs reacted with various human cell lines of lymphoid and nonlymphoid origins, including HTLV-1-positive T-cell lines. Furthermore, they all reacted with a murine A9 clone containing human chromosome 11 fragment q23-pter. Two MAbs, M104 and C33, immunoprecipitated a membrane antigen with the same molecular size. The antigen (henceforth called C33 antigen) was about 40 to 55 kDa in HTLV-1-negative Jurkat, CEM, MOLT-4, and normal peripheral blood CD4-positive human T cells and about 40 to 75 kDa in HTLV-1-positive C91/PL, TCL-Kan, MT-2, and in fresh HTLV-1-transformed CD4-positive human T-cell lines. Pulse-chase experiments revealed that C33 antigen was synthesized as a 35-kDa precursor that was then processed to 41 to 50 kDa in MOLT-4 and to 44 to 70 kDa in C91/PL. In the presence of tunicamycin, a 28-kDa protein was synthesized. The conversion from 35 kDa to 41 to 50 kDa in MOLT-4 and to 44 to 70 kDa in C91/PL was inhibited by monensin. Treatment with N-glycanase alone, but not with sialidase and O-glycanase in combination, completely removed the sugar moiety of C33 antigen from both HTLV-1-negative Jurkat and HTLV-1-positive C91/PL. Therefore, C33 antigen has only N-linked carbohydrates, the modification of which appears to be substantially altered in the presence of the HTLV-1 genome.
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PMID:Identification of membrane antigen C33 recognized by monoclonal antibodies inhibitory to human T-cell leukemia virus type 1 (HTLV-1)-induced syncytium formation: altered glycosylation of C33 antigen in HTLV-1-positive T cells. 173 99

In order to investigate how human immunodeficiency virus (HIV) gains entry to the placenta, we have performed in vitro experiments in which highly purified trophoblast cells isolated from term human placentas were examined for their susceptibility to HIV infection. Trophoblast cells were exposed to cell-free HIV-1 for up to 24 h, after which the cultures were monitored by p24 antigen capture assay, reverse transcriptase assay, and electron microscopy for evidence of virus uptake and replication. None was found. In the second series of experiments, trophoblast cells were cocultured with HIV-infected MOLT-4 cells for 24 h, stained using an anti-HIV antibody, and examined by immunofluorescence microscopy. The MOLT cells were strongly positive, as expected, but many trophoblast colonies also showed a punctate staining pattern. Examination of similar cultures using the electron microscope revealed MOLT cells adherent to trophoblast but no evidence of cell-cell fusion. Virions were observed in coated pits at the trophoblast cell surface and in endosomes or multivesicular bodies in the cytoplasm. These observations are consistent with an endocytosis-mediated mechanism of virus entry. Virions were also observed budding from the trophoblast plasma membrane, indicating that these cells can support HIV replication. To our knowledge, these results show for the first time that HIV can infect placental trophoblast cells in vitro. The results suggest that the placenta could become infected with HIV by the interaction of virus-infected maternal lymphocytes with syncytiotrophoblast bordering the maternal blood in the intervillous space.
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PMID:Cell-mediated infection of human placental trophoblast with HIV in vitro. 174 80

Although human T cell surface glycoprotein CD4 is the cellular receptor for human immunodeficiency virus 1 (HIV-1), the introduction of the human CD4 gene into murine cells does not render them susceptible to HIV-1 infection. Here we have established rabbit transfectant cell lines expressing human CD4 on the cell surface and demonstrated that the CD4+ rabbit transfectants could be readily infected by HIV-1 by co-cultivating with a HIV-1-infected human MOLT-4 T cell line (MOLT-4/HIV). Avid syncytia formation was observed upon co-cultivation and the syncytia abundantly produced HIV-1 mature particles, as revealed by electron microscopy. A significant increase of HIV-1 p24 antigen was also detected in the culture supernatant. The syncytia formation was blocked by pretreating the transfectant with anti-human CD4 or by pretreating the MOLT-4/HIV with anti-HIV-1 serum obtained from an infected individual, indicating that the syncytia formed as a result of the interaction of human CD4 on the rabbit transfectant with the HIV-1 envelope protein expressed on MOLT-4/HIV. In contrast, only a very small proportion of the rabbit transfectants expressed HIV-1-specific antigens upon infection with an HIV-1 stock. This may indicate that, although rabbit cells have partially acquired susceptibility to HIV-1 by transfection of human CD4 gene, rabbit cells may further require such a molecule as might be provided by MOLT-4 to become fully susceptible to HIV-1 infection. The possibility of the rabbit as a model for HIV-1 infection is also discussed.
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PMID:Infection of human CD4+ rabbit cells with HIV-1: the possibility of the rabbit as a model for HIV-1 infection. 176 Apr 13

The V3 loop (residues 303-338) of the human immunodeficiency virus type 1 (HIV-1) gp120 envelope protein represents a principal neutralizing determinant for the virus. An HIV-1 proviral clone containing a mutation in the V3 loop was constructed in which the proline residue at position 313 was changed to an alanine (P313-A). This mutation alters the conserved GPGR sequence that is found in the V3 loop sequences of different HIV-1 isolates. The P313-A clone produced virus particles, which were infectious for a number of T-cell lines including MOLT-4, CEM, and SupT1, but demonstrated a relatively low infectivity on the AA5 B-cell line when compared with wild-type viruses, HTLV-IIIB, HXB2/10 (a chimeric molecular clone), and another mutant virus (Q290-T). V3 loop-specific neutralizing polyclonal sera and the 9284 monoclonal antibody, which recognizes the amino side of the V3 loop sequence, effectively blocked infectivity and syncytia formation of all viruses tested. In contrast, the 0.5 beta monoclonal antibody, which is biologically more potent than 9284 and recognizes a different V3 loop determinant, failed to neutralize the P313-A virus. These results suggest that the proline residue in the relatively conserved GPGR "turn" region of the V3 loop is crucial for recognition by the 0.5 beta antibody. The observed variation in sensitivity of the B-cell line to the P313-A virus may reflect the presence of cell-specific factors which could be important in establishing an HIV-1 infection.
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PMID:Alteration of HIV-1 infectivity and neutralization by a single amino acid replacement in the V3 loop domain. 176 61


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