摘要:

The core of late states of maturing human immunodeficiency virus type 1 (HIV-1) has been visualized in three dimensions at approximately 7 nm resolution by electron microscopic tomography. After budding, approximately 25 nm thick precursor material is observed densely assembled inside the viral envelope. Upon proteolysis the core material is transported and condensed in the center of the virion. The core, 100 nm in length, spans the entire diameter of the virion showing a 40-60 nm wide free end and a narrow end approximately 20 nm. A model of the core is derived consisting of two fibers packed into a bilateral, elongated structure. Two ends of the fibers are compacted together, forming one narrow end of the core, while the two other fiber ends are situated more loosely together allowing for flexibility. Structural maturation of the virus could be reflected by the degree of compactness of the core. The narrow end of the core is observed attached to the envelope with a conspicuous core-envelope link (CEL).

ISSN:0889-2229    

DOI:10.1089/aid.1992.8.1

年代:1992

数据来源: MAL

摘要:

The N-terminal region of the human immunodeficiency virus type 1 (HIV-1) gp41 appears to be involved in virus-cell membrane fusion. To study the influence of fusion domain structure on gp41 interaction with artificial lipid membranes, two families of peptides were synthesized. The peptides of the first family starting from the C-terminal Gly-532 of gp160 (BRU isolate) were assembled in a stepwise manner to N-terminus of gp41(A1a-517). These hydrophobic peptides, containing 10-16 amino acid residues (a.a.), were able to form channel-like current fluctuation through planar lipid membranes, and the longest 15-16 a.a. peptides lysed the liposomes. Peptides of the second family beginning from the C-terminal Arg-538 and continuing to Val-510 contained several hydrophilic amino acid residues. These 15-22 a.a. peptides also increased the conductance of planar lipid bilayers and lysed liposomes. The degree of liposome lysis depended upon peptide length and concentration. The attachment of gp120 C-terminal amino acid or peptides to N-terminus of 517-538 peptide resulted in complete loss of activity. The effects of the second family of peptides on membranes were reduced to a great extent at acidic pH. The conjugation of 22 a.a. Lys peptide with bovine serum albumin decreased its lytic activity. The circular dichroism study of these peptides revealed α-helix configuration in hydrophobic and aqueous media only for deca- and longer peptides. The electron microscopy of 22 a.a. peptide performed in the aqueous medium showed large spherical aggregates about 0.5-0.7 μm in diameter consisting of long filaments approximately 5 nm in diameter. Other tested peptides could generate only short strings. Thus, the effects of fusion peptides on lipid membranes depends on their sequence and length, secondary and tertiary structures, and freedom of their N-terminu

ISSN:0889-2229    

DOI:10.1089/aid.1992.8.9

年代:1992

数据来源: MAL

摘要:

Sulfated polysaccharides have been shown to inhibit human immunodeficiency virus (HIV) infection in vitro. Dextrin sulfate, fucoidan, and dextran sulfate fail to neutralize virions directly, but interact with target cells to inhibit virus entry. Ionic interactions of sulfated polyanions with oppositely charged cell surface components, including CD4, have been assumed to be the inhibitory mechanism. It is shown that the sulfated polysaccharides inhibit infection of both CD4+and CD4-cell lines by HIV and also that they inhibit HTLV-1 and, to a lesser extent, the simian retrovirus, MPMV, which use receptors other than CD4. One binding site for radiolabeled fucoidan on the surface of human T cells is an 18 kD protein, but its significance is not yet clear.

ISSN:0889-2229    

DOI:10.1089/aid.1992.8.19

年代:1992

数据来源: MAL

摘要:

The aim of this study was to determine whether mannosyl-specific lectins, especially Concanavalin A (ConA), may bridge HIV-1envglycoproteins to cell membranes to increase virus binding to its targets, and to what extent this lectin-carbohydrate interaction can modify HIV-1 infectivity for monocytic compared with lymphoid cells. Monocytic U937 and lymphoid CEM cells, which both express surface mannose, were utilized. Whether first incubated withenvglycoprotein or with the cells, lectins bound both to the cells and to radiolabeled recombinant gp160 (rgp160). Thus, they enhanced rgp160 adsorption to the cells in a methyl-α-mannose inhibitable manner. ConA did not appear to bind to the V1 domain of CD4 at the U937 cell surface since Leu3a binding was not blocked in the presence of ConA, nor was recombinant CD4 retained on a ConA-agarose affinity matrix. Moreover, enhanced rgp160 binding to the cells was CD4 independent, since it was not modified by preincubating the cells with Leu3a. Finally, ConA did not inhibit the binding of CD4-IgG3chimeric molecules to virions immobilized on nitrocellulose membrane, which argues against the possibility that it interferes with the interaction of gp120 and CD4. However, both when incubated with the virus or with the cells and despite mediating enhanced binding ofenvglycoprotein, ConA neutralized HIV-1 infectivity for monocytic U937 as well as for lymphoid CEM cells. In this respect, ConA behaves like neutralizing antibodies which do not interfere with CD4 binding of gp120 but rather with some later event that leads to virus entry. These findings obtained with plant lectins may be of relevancein vivo, inasmuch as endogenous mannosyl-binding proteins, which are known to function as opsonins, have been reported to inhibitin vitroinfection by HIV-1

ISSN:0889-2229    

DOI:10.1089/aid.1992.8.27

年代:1992

数据来源: MAL

摘要:

Construction of a DNA plasmid that expresses a diphtheria toxin A chain (DT-A) gene under control of human immunodeficiency virus (HIV-1) proteins Tat and Rev has been described. Here the generation of HeLa cell clones containing integrated, HIV-regulated DT-A sequences is reported. Five such clones were identified by their decreased expression of a luciferase reporter gene transiently cotransfected with Tat- and Rev-encoding plasmids. The decreased luciferase expression most probably was due to activation of the integrated DT-A gene because higher luciferase activity could be restored by introducing either DT antitoxin or a gene encoding a mutant, DT-resistant elongation factor 2 (the intracellular target for DT-A). Analysis by polymerase chain reaction (PCR) indicated that all clones expressed DT-A encoding RNA. The clones were then transfected with an HIV proviral clone and were tested for HIV production; all five clones demonstrated substantially impaired HIV production compared with parental HeLa cells, as shown by p24 assays of culture supernatants. Our success in generating these cell lines indicates that extremely low basal expression has been achieved in view of the high cellular lethality of DT-A. HIV-regulated expression of DT-A may be applicable as a gene therapy approach for the acquired immune deficiency syndrome (AIDS), to bring about selective suicide of HIV-infected cells before production of viral progeny.

ISSN:0889-2229    

DOI:10.1089/aid.1992.8.39

年代:1992

数据来源: MAL

摘要:

Human immunodeficiency virus was detected in the serum/plasma of individuals infected with human immunodeficiency virus (HIV) after capture of virions on microparticles coated with monoclonal antibodies to external and transmembrane proteins of HIV-1. We analyzed serial samples obtained from 6 individuals who seroconverted, 18 asymptomatic, and 12 AIDS patients. HIV-1 RNA was detected in all (29/29) seropositive samples and in 6 seronegative samples immediately preceding seroconversion. In contrast, HIV antigen was detected in 13/29 (45%) of seropositive samples. HIV-1 RNA was also detected in 3 antigen-negative samples from one individual 8-5 months prior to seroconversion and in one sample from another person 2 days before antigen positivity. The intensity of the polymerase chain reaction (PCR) signal paralleled the concentration of HIV antigen. Conversely, seropositive HIV antigen-negative samples gave a weaker PCR signal. HIV-1 RNA was detected in 10/18 (60%) samples from asymptomatic, HIV antigen-negative, individuals and in 11/12 (92%) specimens obtained from AIDS patients. The viral capture method may provide a sensitive, specific, and semiquantitative means of detecting circulating HIV at all stages of infection.

ISSN:0889-2229    

DOI:10.1089/aid.1992.8.47

年代:1992

数据来源: MAL

摘要:

The nucleotide sequence of the gp41 transmembrane protein coding region of human immunodeficiency virus type 1 (HIV-1) proviral DNA obtained from blood and cerebrospinal fluid (CSF) from 6 individuals was determined by direct sequencing of polymerase chain reaction (PCR)-amplified DNA. The direct sequencing approach was performed to avoid errors introduced by Taq polymerase during the amplification reaction. In 3 of 6 paired samples distinct sequence differences between proviral DNA from blood and CSF, ranging from 0.64% to 1.73%, were detected. The greatest diversity (4.2% different amino acids) was found between paired samples of a patient suffering from AIDS encephalopathy, with most of the differences clustering near the carboxy-terminal end of gp41. The results demonstrate that genetically different populations of HIV-1 may be present in different biological compartments and specific neurotropic HIV variants may exist.

ISSN:0889-2229    

DOI:10.1089/aid.1992.8.53

年代:1992

数据来源: MAL

摘要:

Long-term bone marrow cultures (LTBMC) have been infected by two isolates of human immunodeficiency virus type 1 (HIV-1) (HIV-1 LAV and HIV-1 NDK) at multiplicities of infection ranging from 102to 2.106tissue culture infectious units (TCIU) per 106bone marrow mononuclear cells (BMMNC). These infected cells are nonproducer cells and the viruses can be rescued by coculture with peripheral blood lymphocytes, cord blood lymphocytes, or BMMNC and not by the CEM cell line. HIV-1 clearly is not cytopathic for these cells. Following production and growth of erythroid burst-forming units (BFU-E) and erythroid colony-forming units (CFU-E) for at least 6 weeks after infection with HIV-1 NDK, colony assays displayed a 50% inhibition of BFU-E production during 3 weeks of LTBMC. This was followed by a stimulation phase. On the contrary, HIV-1 LAV induces a 150% stimulation of BFU-E production, followed by 50% inhibition. Production of CFU-E was inhibited by 80-100% with the two isolates of HIV-1 after four weeks of LTBMC. Stimulatory and inhibitory activities were recovered from supernatants of infected LTBMC and lymphoid CEM cell lines, suggesting that HIV-1 induces release of a humoral factor responsible for disruption of hemopoietic progenitor cell production in vitro and consequently for hematologic abnormalities in AIDS patients.

ISSN:0889-2229    

DOI:10.1089/aid.1992.8.61

年代:1992

数据来源: MAL

摘要:

In humans, macrophages serve as a major reservoir of human immunodeficiency virus (HIV-1) in the infected host and may play a role in the pathogenesis of the disease. In HIV-1-infected chimpanzees, however, virus could not be recovered from cells of the monocyte/macrophage lineage, leaving the question of macrophage tropism of HIV-1 in this species unresolved. The data reported that HIV-1 IIIB shows dual tropism and is infectious for both chimpanzee monocytes and lymphocytes in vitro. Viral replication in chimpanzee monocytes was clearly demonstrated by infection of allogeneic phytohemagglutinin (PHA) blasts in vitro and by electron microscopy (EM). EM revealed HIV particles associated with 10-15% of the HIV-1 IIIB-infected chimpanzee monocytes. Viral particles budding from the monocyte surface in the typical crescent form were noted as well. This is in contrast to the human situation, where monocytotropic HIV strains preferentially bud into and accumulate in cytoplasmic vacuoles. These results indicate that both lymphocytes and cells of the monocyte/macrophage lineage replicate virus in the chimpanzee; the cell tropism of viral strains, however, is different in chimpanzees and humans.

ISSN:0889-2229    

DOI:10.1089/aid.1992.8.69

年代:1992

数据来源: MAL

摘要:

The virus structural genesgagandenv(both gp120 and gp41 regions) of the 32H isolate of SIVmac251were amplified using the polymerase chain reaction (PCR). The proviral template used in the PCR was DNA isolated from cells used to prepare several experimental SIV vaccines, which have been tested in simians, and a standard challenge stock of virus, which has been used in international collaborative studies. The PCR products were cloned and the nucleotide sequences of several clones were determined for each gene. From a comparison of the sequences obtained the predominant amino acid sequences ofgagandenvwere predicted and the degree of sequence heterogeneity was determined. Conserved and more variable regions of each protein were identified. The gp120 region ofenvwas more heterogeneous thangagor the transmembrane protein ofenv(gp41). Within gp120, sequence variability was concentrated to specific regions equivalent to the V1, V2, and, to a lesser extent, the C1 regions identified for human immunodeficiency virus type 1 (HIV-1). In contrast the region equivalent to the hypervariable "V3-loop" of HIV-1 was highly conserved. The implications of the data is discussed in relation to the ability of this virus stock to prepare effective vaccines against SIV.

ISSN:0889-2229    

DOI:10.1089/aid.1992.8.77

年代:1992

数据来源: MAL