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I Ernberg

Publications and source records attributed to I Ernberg.

At least 73 records · Page 4Linked to original sources
PubMed1989

EBV gene expression in an NPC-related tumour.

A nasopharyngeal carcinoma tumour (designated C15) propagated in nude mice has been used to generate a large cDNA library that we have analysed for Epstein-Barr virus (EBV) gene expression. No gross alterations exist in viral DNA from C15 relative to other human isolates and the large deletion present in the B95-8 'prototype' viral strain established in marmoset cells is not found; C15 contains no linear virion DNA. In the cDNA library, of the six EBV nuclear antigens (EBNAs) expressed in latently infected B-lymphocytes, only clones for EBNA-1 are found. These data are confirmed by immunoblotting. Sequence analysis shows the EBNA-1 mRNA splicing pattern in the carcinoma to differ from that observed in B-lymphocytes. Further, contrary to observations with B-cell lines, most viral transcription in the tumour is localized onto the 'rightmost' region of the conventional EBV physical map. Transcripts identified corresponding to known genes include those for the latent membrane protein (LMP), the alkaline DNA exonuclease and probably the terminal protein; major transcripts are also derived from the BamHI D fragment and the region deleted in B95-8 EBV DNA. Novel transcripts have also been identified that proceed in an anti-sense direction to genes encoding functions associated with replication, such as the viral DNA polymerase. They contain a large, hitherto unidentified, open reading frame in the viral genome that is complementary to the putative function known as BALF3 and a smaller open reading frame complementary to BALF5 (the DNA polymerase gene). From the present studies we can conclude that: (i) EBV transcription patterns in the epithelial cells vary markedly from those identified previously in B-cells, reflecting differential use of promoters or splicing patterns. (ii) Transcription is tightly regulated and restricted in the C15 tumour with many latent genes, notably EBNAs 2-6, being 'switched off.' (iii) A family of cytoplasmic RNAs are transcribed in an antisense direction to a number of existing open reading frames in the EBV genome. (iv) There are a number of mutations in C15 transcripts relative to the B95-8 genome, some of which could result in amino acid alterations in proteins.

Amino Acid Sequence↗
PubMed1989

Epstein-Barr virus-transformed pro-B cells are prone to illegitimate recombination between the switch region of the mu chain gene and other chromosomes.

Six independently maintained sublines of FLEB 14, a fetal-liver-derived Epstein-Barr virus-transformed pro-B cell line that has not yet rearranged its immunoglobulin genes, were examined after in vitro propagation during 19-36 months. Two lines showed no immunoglobulin heavy chain gene rearrangement, whereas one allele was rearranged with breakpoints inside the switch region of the mu chain gene in the remaining four. These rearrangements had been generated by the translocation of different chromosome fragments to the immunoglobulin heavy chain gene cluster-carrying 14q32 band in each of the four lines. Previously, a similar rearrangement was found in a fifth subline concurrently with a reciprocal 6;14 translocation. The transposed pieces have been derived from chromosomes 16 and 18 in two of the more recently rearranged lines. Their origins could not be determined in the remaining two lines, but they were different from each other and the other three 14q+ markers. The 14q+ marker-carrying variant has replaced its diploid progenitor suggesting that the translocation has conveyed some in vitro growth advantage on its carrier. This was also supported by the duplication of the 14q+ marker and the loss of its normal chromosome 14 homologue in one subline during serial culturing. The vulnerability of the switch region of the mu chain gene to illegitimate recombination at the pro-B stage and the possible relevance of this finding for the origin of the Burkitt lymphoma-associated 8;14 (immunoglobulin heavy chain gene cluster/MYC) translocation is discussed.

B-Lymphocytes↗
PubMed1989

Human immunodeficiency virus 1 tat protein binds trans-activation-responsive region (TAR) RNA in vitro.

tat, the trans-activator protein for human immunodeficiency virus 1 (HIV-1), has been expressed in Escherichia coli from synthetic genes. Purified tat binds specifically to HIV-1 trans-activation-responsive region (TAR) RNA in gel-retardation, filter-binding, and immunoprecipitation assays. tat does not bind detectably to antisense TAR RNA sequences, cellular mRNA sequences, variant TAR RNA sequences with altered stem-loop structures, or TAR DNA.

Base Sequence↗
PubMed1989

The role of methylation in the phenotype-dependent modulation of Epstein-Barr nuclear antigen 2 and latent membrane protein genes in cells latently infected with Epstein-Barr virus.

Seven virus-encoded proteins are regularly expressed in Epstein-Barr virus (EBV)-transformed lymphoblastoid (LCL) cell lines: the EBV nuclear antigens EBNA 1 to 6 and the latent membrane protein (LMP). In nasopharyngeal carcinoma (NPC), only EBNA 1 is regularly expressed; LMP is detected in about 50% of the tumours. In Burkitt's lymphoma (BL) tumours, only EBNA 1 is expressed. Also, in BL-derived cell lines that maintain the phenotypic markers characteristic of the in vivo tumour (group I), only EBNA 1 is expressed. EBV was rescued by induction or cocultivation from one BL cell line with a restricted group I pattern, and from one NPC tumour, into normal B cells. In the resulting LCLs EBNA 1 to 6 and LMP were expressed. We assessed the level of methylation in the genes encoding ENBNA 2 and LMP by restriction fragment analysis using the methylation-sensitive enzymes SmaI and HpaII. These genes were extensively methylated in the group I BL line Rael and the nude mouse-passaged C15 NPC tumour, but were demethylated in the derived LCLs. In the LMP-expressing NPC C15 tumour the 5' flanking region of the gene was hypomethylated, whereas the coding exons were methylated [corrected]. The EBNA 1 coding exon was methylated in the Rael line and in NPC, in spite of expression. In contrast, CpG pairs in oriP were originally hypomethylated and remained so after their transfer to LCLs. The cell phenotype-dependent pattern of EBV gene methylation correlated with the phenotype-dependent pattern of EBNA and LMP expression. The specific patterns of methylation localized to controlling regions (oriP and 5' flanking sequences) also suggest a specific role for methylation in the regulation of EBNA and LMP expression.

Antigens, Viral↗
PubMed1989

5-Azacytidine up regulates the expression of Epstein-Barr virus nuclear antigen 2 (EBNA-2) through EBNA-6 and latent membrane protein in the Burkitt's lymphoma line rael.

Nonproductive infection of B lymphocytes by Epstein-Barr virus (EBV) is associated with a highly restricted expression of viral genes. In growth-transformed lymphoblastoid cell lines, the products of these genes include a complex of at least six EBV nuclear antigens (EBNAs) (EBNA-1 through EBNA-6) and one membrane protein (latent membrane protein [LMP]). EBV-carrying Burkitt's lymphoma (BL) biopsies and derived cell lines that have retained a representative phenotype (group I BL lines) express only EBNA-1 (M. Rowe, D. T. Rowe, C. D. Gregory, L. S. Young, P. J. Farrell, H. Rupani, and A. B. Rickinson, EMBO J. 6:2743-2751, 1987). We have found that EBNA-2 through EBNA-6 and LMP can be up regulated by treating the group I BL line Rael with the DNA-demethylating agent 5-azacytidine (5-AzaC). The drug acted in a time- and dose-dependent manner. EBNA-2-positive cells were detected by anti-complement immunofluorescence staining just 12 h after addition of 4 microM 5-AzaC and reached a maximum number at 72 h, when up to 75% of the population was positive. EBNA-2, EBNA-3, EBNA-4, EBNA-4, EBNA-6, and LMP were demonstrated immunoblots starting at 48 h. The EBV-encoded early antigens and viral capsid antigens were also induced but at a lower level. EBNA-2 and the lytic cycle-associated antigens appeared with a different time course and in largely nonoverlapping cell subpopulations, as demonstrated by double fluorescence staining. Thus, EBNA-2 expression was not restricted to lytically infected cells, nor was EBNA-2 required for entry into the lytic cycle. The coding and regulatory sequences of EBNA-2 and LMP were found to be highly methylated in Rael cells and were, as expected, demethylated after 5-AzaC treatment. These findings suggest that DNA methylation may participate in the regulation of growth transformation-associated viral genes in BL cells.

Antigens, Viral↗
PubMed1989

The role of Epstein-Barr virus in lymphomas of HIV-carriers.

A substantial proportion of the lymphomas in HIV-carriers are EBV positive. Together with the fact that there are multiple signs of EBV-activation in AIDS-patients and patients with ARC or PGL, this suggests that these virus carrying tumors develop as results of the immunosuppression, and that EBV has an important role in their pathogenesis.

AIDS-Related Complex↗
PubMed1988

Expression of Epstein-Barr virus-encoded proteins in nasopharyngeal carcinoma.

Expression of the Epstein-Barr virus (EBV) encoded nuclear antigens (EBNA 1 to 6) and membrane-associated protein (LMP) was investigated by immunoblotting in 83 nasopharyngeal carcinoma (NPC) biopsies and 25 other tumor and normal tissue specimens from the head and neck region. Fifty-eight of the 83 NPC biopsies were large enough to yield parallel data on virus DNA and viral expression. All 16 cases of clinically diagnosed and histologically confirmed NPCs from North Africa contained EBV DNA and expressed EBNA-1. Of 31 clinically diagnosed NPCs from China, 29 contained EBV DNA and 25 of these expressed EBNA-1. One control tissue biopsy from the oropharynx of NPC patients contained EBV DNA, but none expressed EBNA-1. The latent membrane protein (LMP) was detected in 22/31 of the Chinese and in 10/16 of the North African NPC biopsies. None of the NPC biopsies or control tissues expressed detectable amounts of EBNA 2 or any of the other 4 nuclear antigens which are invariably expressed in EBV-transformed B cells. A smaller number of tumors from Malaysia and East Africa exhibited a similar pattern of expression. EBV was rescued from a nude-mouse-passaged North African NPC tumor by co-cultivation of the tumor cells with umbilical cord blood lymphocytes. The tumor expressed EBNA 1 and LMP, but not EBNA 2 or the other 4 EBNAs. The resulting LCLs expressed all 6 nuclear antigens, EBNA 1 to 6 and LMP. Our data suggest that expression of the EBV genome is regulated in a tissue-specific fashion.

Animals↗
PubMed1988

Management of Epstein-Barr virus infections.

Both oral and intravenous acyclovir administration for seven days in the early stages of infectious mononucleosis caused an inhibition of oropharyngeal Epstein-Barr virus (EBV) replication. Minimal effect on clinical symptoms was observed. Development of normal cellular and humoral EBV-specific immunity was seen in all patients. The combination of intravenous acyclovir and prednisolone treatment for 10 days in 11 patients with fulminant mononucleosis caused transient cessation of virus shedding in all patients. A dramatic clinical effect on pharyngeal symptoms and on fever was seen in nine of 11 patients within 72 hours. Treatment with chemotherapy or irradiation is recommended in EBV-associated B cell lymphomas seen in immunosuppressed, transplanted, and human immunodeficiency virus-I seropositive patients. No effect of acyclovir has been reported, but such therapy may be considered in the early stage when EBV induces a polyclonal B cell activation. Acyclovir treatment is effective in the EBV-genome positive hairy leukoplakia in human immunodeficiency virus-seropositive patients. No effect of antiviral therapy has been reported in the X-linked lymphoproliferative syndrome. Prophylactic use of immunoglobulin or acyclovir has been suggested in susceptible children.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Absence, or low expression, of leukocyte adhesion molecules CD11 and CD18 on Burkitt lymphoma cells.

Leukocyte adhesion to cells is mediated by the cell-surface glycoprotein complex CD11a-c/CD18 and, in some cases, the glycoprotein gp84. The process is associated with leukocyte activation and modulates lymphocyte proliferation and maturation. Epstein-Barr virus (EBV)-transformed normal B lymphocytes give rise to lymphoblastoid cell lines (LCLs) which grow as large clusters mediated by adhesion molecules. In contrast, newly explanted EBV-infected Burkitt lymphoma (BL) cells usually grow as single cells or as loose clusters. We now report that EBV positive- and EBV-negative BL lines lack the adhesive protein complex, or have only low levels of it, whereas LCLs, representing various stages of B-lymphocyte development, contain considerably higher amounts, as measured by immunofluorescence flow cytometry and immunoprecipitation. The level of gp84 expression is of the same magnitude in both types of cells.

Antibodies, Monoclonal↗
PubMed1988

Eradication of Epstein-Barr virus by allogeneic bone marrow transplantation: implications for sites of viral latency.

Wild-type strains of Epstein-Barr virus (EBV) can be distinguished on the basis of variations in the molecular weight of virus-encoded, growth transformation-associated proteins. This approach was used to study the persistence of EBV in two seropositive recipients of allogeneic bone marrow transplants. The first patient received marrow from her EBV-seronegative brother, became EBV seronegative after grafting, and remained so for greater than 1200 days. Subsequently, she became infected with a new EBV strain that differed from her pretransplant strain but was indistinguishable from the virus isolated from her husband. The second patient received marrow from his EBV-seropositive brother. This patient showed only a transient decrease in IgG antibodies to EBV capsid antigen. His pretransplant strain differed from the virus of his donor. On days 252 and 915 after transplantation, lymphoblastoid cell lines were grown from the peripheral blood of the patient and were found to carry exclusively the virus of the donor. These results suggest that the latently EBV-infected host cells reside in a cellular compartment that can be destroyed by graft-versus-host reactivity, irradiation, or cytotoxic drugs. Hemopoietic tissue is the most likely candidate.

Adult↗
PubMed1987

Progenitor and pre-B lymphocytes transformed by Epstein-Barr virus.

By rosetting with SRBC coupled to rabbit-anti-human IgM, the surface IgM-negative cells of human fetal bone marrow were enriched, and subsequently infected and transformed by Epstein-Barr virus (EBV). Single clones of the transformed cells were obtained. Ninety percent of the resulting cell clones were surface-immunoglobulin-negative, and of 8 clones which were further studied, 5 lacked intracellular, cytoplasmic Ig as measured by immunofluorescence. Control cell clones derived from the same material without pre-selection expressed surface Ig and also secreted Ig. Utilization of a panel of B-cell-specific monoclonal antibodies (MAbs) showed no difference between the cell clones expressing surface Ig and those that did not. The progenitor B-cell lines did not show a phenotype resembling that of cell lines derived from B-cell malignancies, such as high agarose clonability. In spite of their immature Ig-phenotype, these clones showed rearrangement of at least one heavy chain Ig-allele. Efforts to induce differentiation in these clones were unsuccessful. These clones may represent progenitor B cells, or B cells with faulty heavy-chain rearrangement. EBV can apparently be used as a tool to derive cell lines representing different levels of B-cell differentiation, and can also transform immature B cells, which may be useful in the analysis of B-cell differentiation.

Antibodies, Monoclonal↗
PubMed1987

Activation of B lymphocytes by Epstein-Barr virus/CR2 receptor interaction.

Epstein-Barr virus (EBV) infects and transforms human B lymphocytes. The virus receptor was shown to be identical to the complement receptor CR2. The consequences of EBV/CR2 receptor interaction on B lymphocyte activation were analyzed by infection of B cells with the transforming (B95-8) and the nontransforming (P3HR1) virus strains and with UV-inactivated B95-8 virus. Similar to mitogens and antibodies against surface IgM and CR2 receptor, transforming and nontransforming EBV induced the release of leukocyte migration inhibitory factor (LIF). LIF production occurred early after infection and was not affected by irradiation of the B95-8 virus with doses of UV-light which prevented the expression of viral functions. B lymphocytes infected with UV-inactivated virus responded to T cell-derived B cell growth factors. The results demonstrate that binding of EBV to the CR2 receptor activates the B cells. Progression of the infected cells in the activation pathway required helper cell-derived factors or signals provided by the intact viral genome. The nontransforming P3HR1 virus induced a low level of RNA synthesis and increase of cell size and major histocompatibility complex class I antigen expression. Only the transforming virus induced expression of EBV nuclear antigens and cellular DNA synthesis.

Antibodies↗
PubMed1987

Acyclovir treatment in infectious mononucleosis: a clinical and virological study.

Fifty-six patients with a clinical and laboratory diagnosis of infectious mononucleosis who had not been ill for more than seven days, were randomised for peroral treatment with acyclovir (800 mg five times daily) or placebo for seven days in a double blind trial. Clinical, virological and immunological parameters were monitored in each patient for six months. During treatment, shedding of Epstein-Barr virus' as assessed in 36 patients, was significantly reduced (p less than 0.001). However, virus production in the oropharynx returned to pre-treatment levels one week after the cessation of therapy. Virus was detected in 35 patients at enrollment and in 28 of 36 patients at the six-month control. No effect on the clinical course of the disease was noticed. The virus-specific antibody response was also unaffected. A significant reduction in spontaneous outgrowth of in vivo Epstein-Barr virus-infected B-lymphocytes was found at 180 days after treatment in four acyclovir-treated patients compared to six controls (p less than 0.001). In another three patients with over-whelming clinical symptoms causing airway obstruction and/or disseminated intravascular coagulopathy, treatment with intravenous acyclovir (10 mg/kg three times daily) was combined with prednisolone (0.7 mg/kg daily) for ten days. Virus shedding ceased transiently during treatment, but returned to initial levels within one week. A dramatic clinical effect on the pharyngeal oedema and general health of the two patients with airway obstruction was noticed, but was much less evident in a patient with intravascular coagulopathy.

Acyclovir↗
PubMed1987

Analysis of Epstein-Barr virus-specific and non-specific immune functions in a patient during the development of a non-Hodgkin's lymphoma.

A 57-year-old woman who presented with a reactive non-malignant lymphadenopathy was observed subsequently during the development of a nodular centroblastic non-Hodgkin's B-cell lymphoma. The Epstein-Barr virus (EBV)-specific antibody profile and EBV-specific and non-specific cell-mediated immune functions were determined at first presentation, and at various times during progression, in order to determine whether EBV was causally involved in the lymphoma and to assess in general the patient's cell-mediated immune function. At presentation, an immunodeficient status was suggested by an EBV-specific antibody profile indicative of an activated persistent infection; high antibody titers to viral capsid antigen (VCA) and early antigens (EA), but a low level of antibodies to EBV nuclear antigen (EBNA) confirmed by lack of leukocyte migration inhibition in response to EBNA (LMI-EBNA). The number of positive cells reactive with OKIa1 monoclonal antibody was significantly depressed, as was also the natural and interferon-activated killing (NK-IAK). After emergence of the lymphoma, NK-IAK reactivity and spontaneous lymphocyte DNA synthesis augmented in parallel with an increase in the frequency of Leu-7+ blood lymphocytes. The EBV-specific cell-mediated response, reflected by the outgrowth inhibition (OI) test was abolished in parallel with a decrease in the frequency of OKT3- and OKT4-positive lymphocytes.

Cell Migration Inhibition↗
PubMed1987

Antibody responses to Epstein-Barr virus-determined nuclear antigen (EBNA)-1 and EBNA-2 in acute and chronic Epstein-Barr virus infection.

Five distinct Epstein-Barr virus (EBV)-determined nuclear antigens (EBNA-1 to EBNA-5) were recently identified. Antibody responses to these antigens could conceivably differ, and thus prove of serodiagnostic value, in EBV-associated disease processes. As a first step, murine or human cell lines transfected with appropriate EBV DNA fragments and stably expressing either EBNA-1 or EBNA-2 were used to determine the frequency and time of emergence of antibodies to these two antigens in the course of acute and chronic infectious mononucleosis (IM) and to assess their titers in so-called chronic active EBV infections. Following IM, antibodies to EBNA-2 arose first and, after reaching peak titers, declined again in time to lower persistent or even nondetectable levels. Antibodies to EBNA-1 emerged several weeks or months after anti-EBNA-2 and gradually attained the titers at which they persisted indefinitely. The ratios between the anti-EBNA-1 and anti-EBNA-2 titers therefore were generally well below 1.0 during the first 6-12 months after IM and turned to well above 1.0 during the second year. In clear cases of chronic IM, the inversion of this ratio was delayed or prevented. In the less well-defined chronic EBV infections, low ratios were observed in only some of the patients. Because many of these illnesses were not ushered in by a proven IM and often showed EBV-specific antibody profiles within the normally expected range, a causal role of the virus in these cases remains doubtful.

Acute Disease↗
PubMed1987

Monoclonal and polyclonal antibodies against Epstein-Barr virus nuclear antigen 5 (EBNA-5) detect multiple protein species in Burkitt's lymphoma and lymphoblastoid cell lines.

The Epstein-Barr virus nuclear antigen 5 (EBNA-5) is encoded by highly spliced mRNA from the major IR1 (BamHI-W) repeat region of the virus genome. A mouse monoclonal antibody, JF186, has been raised against a synthetic 18-amino-acid peptide deduced from the EBNA-5 message of B95-8 and Raji cells. The antibody showed characteristic coarse nuclear granules by indirect immunofluorescence and revealed multiple EBNA-5 species by immunoblotting and immunoprecipitation. The B95-8 line itself and all B95-8 virus-carrying cells, whether lymphoblastoid cell lines or in vitro-converted sublines of Epstein-Barr virus (EBV)-negative Burkitt's lymphoma (BL) lines, were EBNA-5 positive. Among 36 cell lines carrying different EBV strains, only 10 expressed the B95-8-Raji-prototype EBNA-5 recognized by JF186; this was probably due to genetic variation in the epitope recognized by JF186, as shown for P3HR-1. Human antibodies, affinity purified against EBNA-5-JF186 immunoprecipitates, detected EBNA-5 in the majority of EBV-positive BL lines and in all lymphoblastoid cell lines containing the BL-derived viruses. Thus, EBNA-5 can be expressed by all virus isolates examined, but is down-regulated, together with other latent gene products, in a minority of BL lines which have a particular cellular phenotype. EBNA-5 was detected as a ladder of protein species of 20 to 130 kilodaltons (kDa), with a regular spacing of 6 to 8 kDa, consistent with the coding capacity of the combined BamHI-W 66- and 132-base-pair exons, together with shifts of 2 to 4 kDa, consistent with the size of the separate 66- and 132-base-pair exons. Multiple EBNA-5 proteins can be expressed by the single cell as shown by cloning of newly infected cells.

Animals↗