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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Simian immunodeficiency viruses have been isolated from African green monkeys originating from Ethiopia. A molecular clone, termed SIVagm3, was found to be highly divergent from SIVagmTYO-1 in terms of its restriction map and partial nucleotide sequence. A premature stop codon present in the transmembrane protein of SIVagm TYO-1 was absent in SIVagm3. SIVagm3 was biologically active in vitro and in vivo and displayed characteristics reminiscent of the wild-type virus. Biological activity was demonstrated by seroconversion of juvenile African green monkeys and Macaca nemestrina after inoculation. In contrast to antibody reactivity mainly directed against env proteins in naturally infected African green monkeys. African green monkeys and M. nemestrina infected with the cloned virus showed antibody reactivity directed against all major proteins as demonstrated by immunoblot analysis. The availability of a biologically fully competent molecular clone of SIVagm allows us now to address various pertinent questions in an animal model system which should help to understand features of human immunodeficiency virus infection in human beings.
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PMID:Molecularly cloned simian immunodeficiency virus SIVagm3 is highly divergent from other SIVagm isolates and is biologically active in vitro and in vivo. 268 53

Intrathecal antibody responses to HIV were investigated by a highly sensitive immunoblot assay. Serum and CSF specimens were tested for reactivity with the recombinant HIV gag proteins p15, p17 and p24 and with the recombinant transmembrane protein p41. Autochthonous production of virus-specific IgG to one or more HIV structural proteins was seen in 8 of 10 asymptomatic seropositive subjects, in 3 of 4 men with AIDS-related complex, and in 9 of 13 patients with AIDS. These results were consonant with an elevated CSF/serum antibody ratio to total HIV antigen. The high frequency of local HIV-specific antibody synthesis in seropositive individuals without related clinical symptoms indicates an early involvement of the CNS in HIV infections.
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PMID:Analysis of oligoclonal antibody bands against individual HIV structural proteins in the CSF of patients infected with HIV. 270 64

Various approaches have been considered for generation of effective and safe vaccines against retroviruses, including HIV, with limited success. In the present vaccination study, encompassing 137 household cats, we have composed an experimental ISCOM subunit vaccine containing gp70 of feline leukaemia virus (FeLV)--the external glycosylated envelope protein, and the transmembrane protein p15E, with a commercial available inactivated FeLV vaccine (Leukocell). The two vaccines were estimated to contain approximately the same amount of gp70 antigen and the cats were immunized three times according to the recommendations of the commercial vaccine. A control preparation not containing gp70 or p15E was also included. During the observation period of 200 days all cats remained healthy and no virus was isolated during the isolation attempts. The serological responses were measured in ELISA, membrane immunofluorescence (MIF) and virus neutralization (VN) tests. In contrast to the cats in the other groups almost all ISCOM-vaccinated cats responded by seroconversion or increased titres in the three tests. The development of specific antibodies to gp70 and p15E were confirmed in Western blot. These results clearly illustrate the potential of the ISCOM structure for the development of safe and effective vaccines against retroviruses.
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PMID:Serological responses in cats vaccinated with FeLV ISCOM and an inactivated FeLV vaccine. 275 Feb 71

A method for preparative isolation of human monoclonal antibody isoproteins is described in the present paper. A human monoclonal antibody directed against the transmembrane protein gp 41 from the human immunodeficiency virus (HIV-1) was used in this study. The antibody belongs to the IgG1 subtype and exhibits antibody dependent cellular cytotoxicity. The resolving power of conventional preparative protein separation techniques such as ion-exchange chromatography, chromatofocusing and lectin affinity chromatography is too poor for a complete separation of isoproteins. The more sophisticated technique of chromatofocusing on FPLC-based material (Mono P, Pharmacia) did not satisfy our expectation. With semipreparative IEF in immobilized pH gradients we were able to prepare the different isoproteins of a human monoclonal antibody in milligram amounts. No significant difference between the single isoproteins with respect to specificity and avidity to the recombinant antigen (rec gp 160) was detected. Therefore, we assume that the separation conditions did not influence the immunochemical nature of the antibody and significant denaturation and/or precipitation of the IgG did not occur. Furthermore the method affords preparative separation with resolution equivalent to analytical runs. Experiments for scale up and further characterization of isoproteins (carbohydrate composition, amino acid analysis, half life times etc.) are in progress.
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PMID:Isolation of human monoclonal antibody isoproteins by preparative isoelectric focusing in immobilized pH gradients. 277 64

A synthetic pentadecapeptide (A15; env residues 599-613: SGKLICTTAVPWNAS), derived from a hydrophobic region in the transmembrane protein gp41 of HIV-1 and comprising a highly immunoreactive antigenic site in eliciting antibody responses during HIV-1 infection in humans, was used to purify, by affinity, the corresponding anti-peptide antibodies from HIV-1-infected patient sera. The purified antibodies to peptide A15 reacted specifically with the peptide in EIA, but not in whole virus EIA. These antibodies were immunoreactive with the corresponding peptide-albumin conjugates in immunoblotting but not with gp41 molecules. The results suggest that the peptide A15 sequence is not exposed in intact gp41, but will be exposed and is antigenic in the course of HIV-1 infection in humans.
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PMID:Highly immunoreactive antigenic site in a hydrophobic domain of HIV-1 gp41 which remains undetectable with conventional immunochemical methods. 313 38

Genetic comparison of SIVmac to the human retroviruses generally associated with AIDS revealed a closer relationship to HIV-2 than to HIV-1. A common feature differentiating SIV and HIV-2 from HIV-1 is the size of the transmembrane portion of the envelope, which is smaller (gp32) in SIVmac and HIV-2 than in HIV-1 (gp41). The presence of this truncated form of the transmembrane glycoprotein in SIVmac and HIV-2 virions is apparently related to the presence of a translation termination codon in the env gene of all SIV proviruses analyzed as well as in one HIV-2 provirus. Since the carboxy terminus of the envelope transmembrane protein has been implicated in the cytopathic effect of HIV-1 in vitro, we decided to investigate whether putative expression of the open reading frame located after the termination codon correlates with the pathogenicity of SIVmac in vivo. We generated two synthetic peptides from the inferred amino acid sequence of SIVmac and tested their reactivity by Western blot against the sera of naturally and experimentally infected monkeys as well as against sera of HIV-2-infected individuals. Our results indicate that the protein synthesized from this open reading frame is expressed in vivo, since an immunoresponse can be detected against the synthetic peptides in two of three experimentally SIVmac-infected animals. However, no correlation can be found between its expression and disease progression at this time. Furthermore, a rabbit immune serum raised against the synthetic peptide failed to identify any specific protein in SIVmac-infected cells.
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PMID:The simian immunodeficiency virus envelope open reading frame located after the termination codon is expressed in vivo in infected animals. 314 95

To evaluate the performance of a serological test for human immunodeficiency virus type 1 (HIV-1) infections based on the use of a recombinant envelope gene-derived protein as the antigen, we caused expression of a 1.4-kilobase fragment of HIV.DNA that codes for the complete gp41 transmembrane protein in an Escherichia coli expression vector and used Western blots (WB; immunoblots) prepared with recombinant material (pEX-41) to detect antibodies to HIV-1. This test detected all 339 sera which were positive by a combination of conventional serodiagnostic assays and produced no false-positive results with 311 negative samples. Also no false-positive results were obtained with 20 sera from systemic lupus erythematosus patients which had high titers of cross-reactive autoantibodies. In six cases, the pEX-41 WB proved to be more sensitive than individual assays applied on their own, and in five cases it was even more sensitive than a combination of conventional assays. We tested 221 sera in both our pEX-41 WB and a commercially available recombinant enzyme immunoassay (EIA [Abbott]). The results were identical in 188 cases. A total of 27 sera containing antibodies to gp41 as demonstrated in the pEX-41 WB, as well as the Abbott recombinant EIA, had no antibodies to the recombinant core antigen as measured in the Abbott EIA. However, 25 of these sera did stain the 24-kilodalton band on a WB with purified virus. Six sera that were positive in all of the conventional confirmatory assays and reacted strongly with the pEX-41 WB did not recognize the surface antigen used in the Abbott recombinant EIA. We conclude that the use of WB prepared with recombinant-derived p41 offers a very sensitive and specific method to detect antibodies to HIV.
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PMID:Comparison of Western blot (immunoblot) based on recombinant-derived p41 with conventional tests for serodiagnosis of human immunodeficiency virus infections. 327 88

Serologic testing for human immunodeficiency virus type 1 (HIV-1) is currently based on enzyme linked immunosorbent assay (ELISA) as screening method. Positive ELISA-results have to be confirmed by at least one second procedure such as Western blotting or immunofluorescence. To obtain new diagnostic reagents for confirmatory testing, we expressed viral antigens in procaryotic systems. Peptides representing epitopes of structural core (gag)- and envelope (env)-proteins of HIV were produced in E. coli as stable immunogenic beta-galactosidase fusion proteins. Recombinant proteins were taken for immunoblot-assays. The results of Western blotting with those fusion proteins were in general comparable with conventional ELISA, immunofluorescence, immunoblot with cell-culture derived virus and commercially available ELISA tests based on recombinant proteins. Immunoblots using recombinant transmembrane protein (gp41) derived polypeptide were more sensitive than the conventional procedure with purified virion proteins. Western blotting with recombinant fusionproteins provide reliable and inexpensive serodiagnostics without handling of infectious cell cultures.
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PMID:[Serologic AIDS diagnosis with polypeptides obtained by genetic technics of the human immunodeficiency virus (HIV-1)]. 332 45

The stability of potential RNA stem-loop structures in human immunodeficiency virus isolates, HTLV-III and ARV, has been calculated, and the relevance to the local significant secondary structures in the sequence has been tested statistically using a Monte Carlo simulation method. Potentially significant structures exist in the 5'non-coding region, the boundary regions between the protein coding frames, and the 3' non-coding region. The locally optimal secondary structure occurring in the 5' terminal region has been assessed using different overlapping segment sizes and the Monte Carlo method. The results show that the most favorable structure for the 5' mRNA leader sequence of HIV has two stem-loops folded at nucleotides 5-104 in the R region (stem-loop I, 5-54 and stem-loop II, 58-104). A large fluctuation of segment score of the local optimal secondary structure also occurs in the boundary between the exterior glycosylated protein or outer membrane protein and transmembrane protein coding region. This finding is surprising since no RNA signals or RNA processing are expected to occur at this site. In addition, regions of the genome predicted to have significantly more open structure at the RNA level correlate closely with hypervariable sites found in these viral genomes. The possible importance of local secondary structure to the biological function of the human immunodeficiency virus genome is discussed.
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PMID:Stability of RNA stem-loop structure and distribution of non-random structure in the human immunodeficiency virus (HIV-I). 338 21

Cell fusion is a characteristic cytopathic effect induced by the human immunodeficiency virus (HIV) that leads to the formation of syncytia between infected lymphocytes. Although this process has been shown to occur following the specific binding of the 110-120 kD externalized envelope molecule of the virus with the CD4 glycoprotein, the region of the HIV envelope that directly mediates cell fusion is unknown. In an attempt to identify this fusion domain, we compared the amino acid sequences from the envelope molecules of several HIV isolates to the fusion proteins of paramyxoviruses. We found that the amino terminal region of the HIV transmembrane protein gp41 had a striking degree of similarity with the fusion domain of the respiratory syncytial virus. Moreover, similar sequences were noted in the fusion proteins of other paramyxoviruses and the transmembrane envelope proteins of a variety of lentiviruses suggesting that a functional relationship exists between these glycoproteins. This finding indicates that the amino terminal region of the HIV gp41 molecule may mediate cell fusion for this virus, and could be an important target in the design of immunologic strategies for the prevention of HIV infection in vivo.
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PMID:Sequence similarities between human immunodeficiency virus gp41 and paramyxovirus fusion proteins. 350 26


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