Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We analysed the terminal repeats of Epstein-Barr virus (EBV) in DNAs isolated from six lethal midline granuloma (LMG) biopsies. A single fused terminal fragment could be detected in each case, indicating that these angiocentric peripheral T cell lymphomas represent clonal proliferations of cells infected with EBV on a single occasion. Using reverse transcriptase-PCR, we detected EBV nuclear antigen (EBNA) 1 and latent membrane protein (LMP) 1, but not EBNA 2 messages in LMG biopsy RNAs. The splicing pattern of the EBNA 1 message was consistent with the usage of a promoter localized in the BamHI F fragment (F promoter). The BamHI W fragment repeats and LMP-coding sequences were highly methylated in all cases. In contrast, the LMP regulatory sequences were found to be hypomethylated or partially methylated, as in LMP-expressing nasopharyngeal carcinomas.
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PMID:Clonality, expression and methylation patterns of the Epstein-Barr virus genomes in lethal midline granulomas classified as peripheral angiocentric T cell lymphomas. 811 42

Clones of human B lymphocytes, obtained after immortalization with Epstein-Barr virus (EBV) of single CD19+ B cells and expansion in the absence of human T lymphocytes, produced mRNA for the T cell cytokines interleukin(IL)-2, IL-4, and interferon (IFN)-gamma. As detected by reverse transcriptase-polymerase chain reaction, IL-2 mRNA was expressed only after stimulation with the combination of phorbol 12-myristate 13-acetate (PMA) plus ionomycin. IL-4 mRNA was constitutively detectable in all (10/10) EBV-transformed B cell clones, and the mRNA for IFN-gamma was constitutively present in half of the clones. In contrast to IL-2 mRNA, the expression of IL-4 and IFN-gamma mRNA could be increased by PMA alone. Most of the clones produced IL-2 bioactivity and immunoreactive protein, but neither IL-4 nor IFN-gamma protein secretion was detected. The intriguing question raised by these results is whether IL-2 secretion could contribute to the immune control of EBV-infected B lymphocytes by cytolytic T cells, and whether normal B lymphocytes can potentially be induced to express certain cytokines including IL-4 in response to the appropriate activation signals.
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PMID:Differential induction of T cell cytokine mRNA in Epstein-Barr virus-transformed B cell clones: constitutive and inducible expression of interleukin-4 mRNA. 838 61

Epstein-Barr virus (EBV) is detectable in approximately 40% of cases of Hodgkin's disease (HD). The viral genomes remain latent but positive staining with anti-ZEBRA antibody in a small fraction of Reed-Sternberg (RS) cells of some cases of HD would suggest possible activation of EBV replication within these cells. We report the investigation of 40 cases of EBV-associated HD (including 5 human immunodeficiency virus [HIV]-positive cases) using anti-ZEBRA antibodies. Positive staining was found in only three (HIV-negative) cases. One of these three cases showed approximately 1% of ZEBRA-positive tumor cells, whereas the other two cases showed rare positive cells. In the case with 1% ZEBRA-positive cells, a strong signal was obtained with anti-EA-R antibody and BHLF1 oligoprobes, which indicated early gene expression. EBV replication could be shown in this case by nonisotopic in situ DNA-DNA hybridization, which showed markedly increased numbers of EBV genomes in a few RS cells. Viral replication was confirmed using reverse transcriptase and polymerase chain reaction that detected transcripts from the BLLF1 gene encoding for the membrane antigen gp350/220. EBV replication in RS cells seems to be an exceptional event but may provide clues to mechanisms of control of viral latency and assume clinical implications in the future.
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PMID:Demonstration of Epstein-Barr virus replication in Reed-Sternberg cells of Hodgkin's disease. 839 54

We have used an efficient cDNA subtraction library procedure to identify newly induced genes in human B lymphocytes infected for 6 h with Epstein-Barr virus (EBV). Among the genes identified by automated sequencing of a random subset of clones from this library, one coded the EBV BCRF1 open reading frame, which specifies the viral interleukin 10 gene (vIL-10). This molecule is highly homologous to human (h)IL-10 and was previously thought to represent a "late" viral gene expressed only during the lytic phase of virus replication. Using gene amplification by reverse transcriptase polymerase chain reaction of B cell RNA obtained at varying times after infection, we detected vIL-10 expression within a few hours of EBV infection, followed, 20-30 h later by expression of hIL-10. Expression of both genes continued beyond the initial transformation phase (5-10 d) and was present in all transformed cell lines tested. When added at the time of viral infection, antisense (but not sense) oligonucleotides for vIL-10 mRNA (cytosolic half-life, approximately 6 h) prevented subsequent B cell transformation. The antisense effect was highly specific, leaving the expression levels of other transformation-related genes intact. Addition of exogenous (h)IL-10 rescued the transformation process in antisense-treated cells. Our observations establish vIL-10 as a new latency gene with a directly transformation-prerequisite function.
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PMID:Viral interleukin 10 is critical for the induction of B cell growth transformation by Epstein-Barr virus. 839 76

A further series of 41 adult patients with late-onset hepatic failure was investigates with respect to aetiological factors, particularly hepatitis C and E, which have been identified since our earlier report of this condition. The increased use of transplantation and its impact on survival overall is assessed. Comparison is made with 64 patients admitted over the same period with fulminant hepatic failure of non-A, non-B aetiology. Screening for the hepatitis viruses revealed three cases of hepatitis A and one case of Epstein Barr virus hepatitis. There were no cases of hepatitis C or hepatitis E virus detected by enzyme immunoassay and reverse transcriptase/polymerase chain reaction techniques, although three patients had positivity for IgG anti-hepatitis E virus, demonstrating previous exposure. Serum autoantibodies in a titre greater than or equal to 1:40 were present in 29% of samples tested and in three cases, titres of SMA or ANF were greater than 1:320. In a further five cases, a potentially hepatotoxic agent had been given within 3 months of the onset of symptoms, leaving the majority of patients (29) with no identifiable cause for their disease. The frequency of symptoms, however, including nausea, abdominal discomfort with the subsequent development of ascites, encephalopathy and renal impairment suggest a similar disease process in these patients. Analysis of liver biopsy material showed similar patterns on all cases of map-like necrosis with nodular regeneration and without other additional features of aetiological significance. Differences in clinical and histological changes for the non-A, non-B fulminant hepatic failure comparison group reflect the tempo of disease process rather than the nature and cause of the liver damage. The introduction of transplantation has led to a marked improvement in survival (39% overall in the earlier series). In the 21 patients in whom transplantation was carried out, the 1-year actuarial survival is currently 55%. Treatment of late-onset hepatic failure with corticosteroids and the use of Prostaglandin E1 and interferon in individual cases has been disappointing, and the emphasis in management should be placed on teh early referral of such patients to a centre offering transplantation.
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PMID:Late-onset hepatic failure: clinical features, serology and outcome following transplantation. 865 52

Malignant lymphomas frequently develop in the pleural cavity of the patients with long-standing pyothorax. Thus, the term pyothorax-associated lymphoma (PAL) has been proposed for this type of tumor. Most PAL are diffuse large cell lymphoma of B cell type that contain Epstein-Barr virus DNA. We have established two lymphoma cell lines from the biopsy specimens of PAL cases, OPL-1 and OPL-2. Because PAL develop in the sites of chronic inflammation, inflammatory cytokines might be involved in the lymphomagenesis. To address this point, we examined the regulation of the growth of OPL by human IL-6. Human recombinant IL-6 enhanced the growth rate of OPL. OPL-1 responded to recombinant IL-6 by growing faster even at concentrations of less than 0.1 ng/ml, whereas OPL-2 required higher concentrations of recombinant IL-6. OPL expressed IL-6 receptor mRNA detectable by reverse transcriptase PCR analysis and IL-6 receptor on cell surface by flow cytometric analysis, using anti-IL-6 receptor antibodies. On the other hand, only OPL-1 showed expression of IL-6 mRNA, which was detectable only by reverse transcriptase PCR, and secreted IL-6 protein into the culture media. The culture supernatant of OPL-1 exhibited growth-enhancing effects on OPL-1 and OPL-2. The addition of anti-IL-6 antibodies to the cultures inhibited the growth of OPL-1 but not OPL-2. OPL-2 did not secrete IL-6 protein into the media, and the culture supernatant from OPL-2 did not enhance growth of OPL-2. These findings suggest the involvement of IL-6 in the growth regulation of OPL, i.e., an autocrine mechanism of IL-6-related proliferation in OPL-1 and a paracrine mechanism in OPL-2. IL-6 locally produced in chronic pyothorax might also promote the development of PAL.
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PMID:Interleukin-6-mediated growth enhancement of cell lines derived from pyothorax-associated lymphoma. 876 17

CD4+ and CD8+ T lymphocytes purified from normal adult donors by flow cytometry could be infected with Epstein-Barr virus (EBV) as measured by the accumulation of components of the EBV replicative cycle, viral DNA and viral transcripts encoding EBER1 and BRLF1. EBV infection resulted in enhanced replication of human immunodeficiency virus type 1 (HIV-1) IIIB in CD4+ lymphocytes as measured by accumulation of reverse transcriptase and formation of syncytia. Furthermore, a small percentage of CD8+ T cells became permissive after infection with EBV. Inactivation of transforming functions by irradiation with UV light greatly reduced the ability of EBV to enhance HIV-1 replication in T4+ T cell, suggesting that live virus is needed for enhancement. These results demonstrate a direct synergy between EBV and HIV-1 during coinfection of T cells in vitro and may explain the beneficial effect of acyclovir in combination with antiretroviral chemotherapy as well as the increased incidence of T-cell lymphomas associated with EBV in patients with AIDS.
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PMID:Infection of primary CD4+ and CD8+ T lymphocytes by Epstein-Barr virus enhances human immunodeficiency virus expression. 879 95

Amplification of viral nucleic acids from the cerebrospinal fluid (CSF) has considerably improved the diagnosis of several acute, subacute and chronic viral infections of the nervous system. In herpes simplex virus (HSV) encephalitis (HSE) the polymerase chain reaction (PCR) has become the method of choice for the rapid, non invasive diagnosis. Other herpes virus associated diseases which can now be reliably diagnosed are encephalitis, ventriculoencephalitis, polymyeloradiculitis, myelitis and an inflammatory polyradiculoneuropathy caused by cytomegalovirus (CMV), HSV, varicella-zoster virus (VZV) or Epstein-Barr virus (EBV), EBV associated primary B-cell-lymphoma of the brain, acute aseptic meningitis in young adults allied with VZV, and meningoencephalitis with recurrent seizures due to human herpes virus type 6 (HHV-6). In AIDS patients, PCR has helped to differentiate lesions either due to the human immunodeficiency virus (HIV) itself or to opportunistic infections such as progressive multifocal leukoencephalopathy (PML) caused by JC virus (JCV) or CMV related complications. HIV can be detected early in the course of infection in the CSF and the amount of proviral DNA in CSF cells seems to be correlated with the severity and/or progression of neurological signs and symptoms. Acute epidemic aseptic meningitis caused by enterovirus infections can now be reliably diagnosed and typed by reverse transcriptase PCR (RT-PCR). Meningitis cases caused by vaccination with the Jeryl Lynn and Urabe vaccine strain of mumps virus have been identified using RT-PCR and sequencing of the amplified products (amplicon).
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PMID:Clinical implications of nucleic acid amplification methods for the diagnosis of viral infections of the nervous system. 879 10

In Epstein-Barr virus (EBV)-associated tumors that arise in immunocompetent individuals, the pattern of viral gene expression is very restricted compared with that of latently infected B cells in tissue culture. A hallmark of viral gene expression in these tumors is the exclusive expression of only one EBV-encoded nuclear antigen, EBNA1, which is driven from a promoter (Qp) that lies near the junction of the viral BamHI F and Q fragments. During induction of the lytic cycle, a viral promoter, Fp, which lies ca. 200 bp upstream of Qp, gives rise to transcripts which overlap with Qp-initiated EBNA1 gene transcripts. Distinguishing between latency-associated EBNA1 gene transcripts and those associated with the early phase of the viral lytic cycle is critical for correct identification of restricted viral latency. Here we describe a reverse transcriptase PCR protocol which employs a nested set of upstream primers from the BamHI Q region of the viral genome and readily distinguishes Fp-initiated transcripts from Qp-initiated transcripts. A single set of amplification conditions was used for the various PCR primer combinations, which allowed all reactions to be run simultaneously. An in vitro-generated transcript, diluted in RNA from an EBV-negative cell line, was used to demonstrate that the efficiencies of amplification with the different primer combinations were very similar. This protocol was used to demonstrate that EBNA1 gene transcription in two previously uncharacterized EBV-positive epithelial cell lines initiates from Qp. In addition, we assessed the site(s) of initiation of EBNA1 gene transcripts in cell lines exhibiting restricted viral latency. Contrary to the results of Nonkwelo et al. (J. Virol. 70:623-627, 1996), which indicated that EBNA1 gene transcription during restricted viral latency initiates at multiple sites downstream of Fp, we show here that nearly all EBNA1 transcripts start at the previously identified Qp transcription initiation site.
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PMID:A simple reverse transcriptase PCR assay to distinguish EBNA1 gene transcripts associated with type I and II latency from those arising during induction of the viral lytic cycle. 889 54

Nasal T/NK-cell lymphomas can be further separated into those of natural killer (NK) cell lineage or of T-cell lineage, with differences in cellular phenotype, T-cell receptor (TcR) gene rearrangement and TcR transcript expression. Both NK- and T-cell subtypes are closely associated with Epstein-Barr virus (EBV). In this study, EBV gene expression was determined in 23 cases of nasal lymphoma (NL) by in situ hybridisation (ISH), reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry (IH). Of the 23 cases, 19 were classified as NK-cell and 4 as T-cell tumours. ISH for EBV-encoded small non-polyadenylated RNAs showed that all cases, whether NK or T, harboured EBV in virtually all tumour cells. RT-PCR demonstrated that NL of both subtypes expressed EBNAI of the QUK splice pattern, the latent membrane proteins, LMP1 and 2 and the BamHI A rightward transcripts in the absence of EBNA2 mRNAs, compatible with the latency type II pattern. In addition, analysis of EBV protein expression by IH revealed a heterogeneous pattern of EBV gene expression at the single-cell level consisting of both LMP1+ and LMP1- tumour cells, suggesting a mixture of latency I and II. Although 2 early lytic transcripts, BZLF1 and BHRF1, were also detected in 13 and 10 cases, respectively, the lack of ZEBRA staining in any case indicates that these lytic transcripts are most likely expressed by rare cells in the biopsies entering lytic cycle. The viral transcriptional pattern similar to that of nasopharyngeal carcinoma and Hodgkin's disease suggests that EBV can exploit common regulatory mechanisms for gene transcription in diverse host cell types. Down-regulation of immunogenic proteins (EBNA2-EBNA6) in nasal lymphoma may enable tumour cells to evade host cytotoxic T-cell surveillance.
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PMID:Nasal NK- and T-cell lymphomas share the same type of Epstein-Barr virus latency as nasopharyngeal carcinoma and Hodgkin's disease. 890 67


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