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

The pX region of the human T-cell leukemia/lymphotropic virus type I (HTLV-I) contains at least four open reading frames (orfI-orfIV). orf III and orf IV encode the regulatory HTLV-I proteins Rex and Tax, which together modulate viral expression, and the p21rex protein of unknown function. By using the reverse transcriptase and polymerase chain reaction techniques on the RNA of an HTLV-I-infected cell culture, we uncovered the existence of alternatively spliced mRNAs generated through the use of three splice acceptor sites. These mRNAs encoded protein isoforms derived from the HTLV-I orf I (p12I) and orf II (p13II and p30II). An additional acceptor splice site, used in the processing of the env and tax/rex mRNAs and a singly spliced mRNA for the p21rex protein, was also identified. All of these HTLV-I mRNAs were also detected in freshly isolated cells from HTLV-I-infected individuals. Thus HTLV-I, like the human immunodeficiency virus type 1, has developed fine posttranscriptional mechanisms to increase the complexity of its genome.
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PMID:Protein isoforms encoded by the pX region of human T-cell leukemia/lymphotropic virus type I. 152 97

The nucleotide sequence of the pol-env intergenic region of two isolates of caprine arthritis-encephalitis virus (CAEV) was determined. Two open reading frames (orfs) were identified, designated Q and S by homology with visna virus. CAEV orf S is a single exon encoding a deduced 87-amino acid gene product sharing 36 amino acid identities with the visna trans-acting transcriptional activator (Tat). Ten of these identities comprise a conserved CGCRLCNPGW sequence similar to a cysteine-rich domain essential for trans-activation by human immunodeficiency virus Tat. To determine if transcription promoted by the CAEV long terminal repeat (LTR) could be stimulated in CAEV-infected goat synovial membrane cells, a plasmid (pCAE-CAT) expressing bacterial chloramphenicol acetyltransferase (CAT) under control of the CAEV LTR was transfected into uninfected and infected cells. Sixfold enhancement of CAT activity was observed in infected cells using 100 ng of transfected plasmid. To determine if the pol-env region encodes a gene product which trans-activates the CAEV LTR, goat synovial membrane cells were cotransfected with pCAE-CAT and pRSV-1.9, a plasmid expressing the pol-env region under control of the Rous sarcoma virus LTR. Results indicated that the CAEV genome encodes a tat gene product attributable to orf S.
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PMID:Genetic structure of the pol-env region of the caprine arthritis-encephalitis lentivirus genome. 184 32

Mutations were made by recombinant DNA techniques in an infectious molecular clone of the human immunodeficiency virus San Francisco isolate 2 (HIVSF2) [formerly the prototype isolate of the acquired immunodeficiency syndrome-associated retrovirus (ARV-2)]. The effect of these changes on the replicative and cytopathologic properties of the virus was studied by transfecting modified virus clones into cultured human cells. Mutations in the gag, pol, env, and tat regions precluded virus replication and cytopathology in lymphoid cells. A mutation in orf-A dramatically reduced but did not abolish virus replication. Mutant viruses with deletions in the orf-B region were highly cytopathic and replicated to approximately 5-fold higher levels than wild-type virus. They also produced approximately 5-fold more viral DNA in infected lymphoid cells than did wild-type virus. Thus, the orf-B region may function to down-regulate virus replication. This mutational analysis of the HIVSF2 genome is a means of assessing genes regulating viral replication and cytopathology.
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PMID:Mutational analysis of the human immunodeficiency virus: the orf-B region down-regulates virus replication. 243 56

Three full-length cDNA clones were obtained from cells infected with the simian immunodeficiency virus (SIV) isolated from captive macaques (SIVMAC). Nucleotide sequence analyses suggested that these represented mRNA for the SIV MAC genes tat, rev (formerly, art/trs), and nef (formerly, 3'orf). The putative tat-specific clone was active in trans-activation of the SIV MAC long terminal repeat in COS-1 and Jurkat cells. In contrast, the human immunodeficiency virus 1 long terminal repeat was significantly trans-activated only in the COS-1 cells. This suggests that trans-activation by the SIV tat gene is modulated by cell-specific factors. The structure of all of the clones suggested an mRNA splicing pattern more complex than that described for human immunodeficiency virus 1.
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PMID:Structure of simian immunodeficiency virus regulatory genes. 254 74

Soon after infection of ovine cell cultures, visna virus expression is first indicated by the accumulation of two multi-spliced transcripts of 1.2 and 1.6 kb that at present we have renamed 1.4 and 1.7 kb according to their exact length. The early 1.4-kb mRNA encodes for a protein which increases the level of transcripts directed from visna virus long terminal repeat (trans-activation). This trans-activating protein was previously called VEP1 and at present is renamed as the product of the rev gene according to significant amino acid sequence homologies between this protein and the rev gene products of simian immunodeficiency virus and human immunodeficiency virus type 2. In this study, the 1.7-kb mRNA was cloned, sequenced, and in vitro translated. It is 1491 nucleotides long, contains two short open reading frames, (orfs), tat (previously orf S) and rev which is the bipartite trans-acting gene specific for the early 1.4-kb mRNA. The tat gene of visna virus encodes for a protein of 11 kDa which in transient expression assays has a positive transacting effect on transcription as the rev gene product does.
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PMID:The open reading frame S of visna virus genome is a trans-activating gene. 254 28

Eight coding regions designated gag, pol, env, sor, R, tat, art/trs, and 3' orf have been identified in the genome of the human immunodeficiency virus type 1 (HIV-1). Several other open reading frames have the potential to encode additional viral proteins. In this study, we show that HIV-1 has another coding sequence whose product is expressed during natural infection. Unlike antibody to other HIV-1 proteins, the prevalence of antibody to the product encoded by this region is elevated in patients with acquired immune deficiency syndrome (AIDS). Because no analogous coding region has been identified in HIV-2, the antibody to the product of this coding region may serve as a marker to distinguish infection with HIV-1 from infection with HIV-2.
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PMID:Human immunodeficiency virus type 1 has an additional coding sequence in the central region of the genome. 284 97

The human spumaretrovirus (HSRV) isolated from a nasopharynx carcinoma patient 17 years ago has a RNA genome 11 kb in size. It encodes besides the gag, pol, and env genes several novel genes (S1 and bel 1, 2, and 3) that are comparable to the regulatory genes R, X, tat, art, and 3'-orf of the human (HIVs) and simian immunodeficiency viruses (SIVs) with respect to genomic location and to sizes of the putative gene products. A comparison between the HIV protein sequences of the pol and the novel genes to the corresponding gene product sequences of HSRV revealed that HSRV is related to the lentiviruses but occupies a distinct phylogenetic placement of its own. A detailed analysis of the reverse transcriptase domain allows the construction of a phylogenetic tree for the known retroviral subfamilies and/or groups, including the oncoviruses, the lentiviruses, the spumaviruses, the HLTV-BLV group, and the D-type viruses. Regions of the putative novel HSRV gene products with segmental protein sequence homology to the regulatory protein of other human retroviruses are discussed. The results strengthen the view that HSRV and its novel genes should be studied in comparison to the new genes of acquired immunodeficiency syndrome (AIDS) viruses and human T cell leukemia viruses (HTLV).
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PMID:Genomic organization of the human spumaretrovirus and its relatedness to AIDS and other retroviruses. 285 7

The genetic diversity of the human immunodeficiency virus (HIV) isolated from transfusion-associated AIDS patients has been examined. Restriction enzyme mapping studies of integrated proviral DNA of donor and recipient origin demonstrated genomic variation between isolates. Analysis of the molecularly cloned viral genomes of one donor-recipient pair showed that virus from the recipient had restriction enzyme site differences from the donor, noticeably clustered in the env and orf-2 regions, and also had a greater number of restriction sites in common with the donor as well. These results suggest that HIV may undergo genomic variation in vivo. Comparison of donor-recipient viruses may further the understanding of the molecular basis for AIDS pathogenesis.
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PMID:Transfusion-associated AIDS: donor-recipient human immunodeficiency virus exhibits genetic heterogeneity. 288

Signs of latent HIV infection were sought in stored serum samples collected before overt seroconversion, confirmed by enzyme-linked immunosorbent assay (ELISA), from 9 subjects with human-immunodeficiency-virus (HIV) infection, in serum from 25 seronegative sexual partners of HIV-seropositive men and from 23 other seronegative, homosexually active men. Free HIV antigen and/or low-titre antibodies to recombinant structural (core, env) or non-structural (3' orf, sor, tat) proteins were seen 6-14 months before seroconversion in all 9 subjects who seroconverted. Antibodies against core proteins detected by western blot were usually the first sign of latent HIV infection. 5 of the 25 ELISA-negative exposed partners have shown HIV antigenaemia and antibodies against core proteins for 16-34 months. By in-situ hybridisation, HIV-specific RNA was detected in peripheral-blood non-lymphoid mononuclear cells in some of the latently infected partners. All subjects with latent HIV infection had normal numbers of T4 lymphocytes but half of them lost their in-vitro proliferative T-cell response to a recall antigen (purified protein derivative of tuberculin). Early HIV infection, characterised by a low-level and restricted antibody response towards HIV core and regulatory proteins, seems mainly to affect antigen-presenting cells.
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PMID:Long latency precedes overt seroconversion in sexually transmitted human-immunodeficiency-virus infection. 288 86

Human immunodeficiency virus 1 (HIV-1) is the aetiological agent of AIDS. The virus establishes lytic, latent and non-cytopathic productive infection in cells in culture. The complexity of virus-host cell interaction is reflected in the complex organization of the viral genome. In addition to the genes that encode the virion capsid and envelope proteins and the enzymes required for proviral synthesis and integration common to all retroviruses, HIV-1 is known to encode at least four additional proteins that regulate virus replication, the tat, art, sor and 3' orf proteins, as well as a protein of unknown function from the open reading frame called R. Close examination of the nucleic acid sequences of the genomes of multiple HIV isolates raised the possibility that the virus encodes a previously undetected additional protein. Here we report that HIV-1 encodes a ninth protein and that antibodies to this protein are detected in the sera of people infected with HIV-1. This protein distinguishes HIV-1 isolates from the other human and simian immunodeficiency viruses (HIV-2 and SIV) that do not have the capacity to encode a similar protein.
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PMID:Identification of a protein encoded by the vpu gene of HIV-1. 304 30


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