Biomedical subjects

N Raab-Traub

Publications and source records attributed to N Raab-Traub.

At least 55 records · Page 3Linked to original sources

PubMed1995

Expression of LMP1 in epithelial cells leads to the activation of a select subset of NF-kappa B/Rel family proteins.

This study demonstrates that the Epstein-Barr virus protein LMP1 activates a specific subset of NF-kappa B/Rel proteins in the C33 epithelial cell line. Western immunoblot analysis used to analyze the intracellular distribution and abundance of the proteins present in these complexes demonstrated that levels of the p50 and p52 proteins were significantly elevated in the nuclei of LMP1-expressing cells. The data also suggest that LMP1 facilitates the translocation of p50 to the nucleus and may affect the processing of the p100 and p105 precursor proteins or the stability of p52 and p50.

Herpesvirus 4, Human↗

PubMed1995

The Epstein-Barr virus 3.5-kilobase latent membrane protein 1 mRNA initiates from a TATA-Less promoter within the first terminal repeat.

The complete 5' sequence of the Epstein-Barr virus 3.5-kb latent membrane protein 1 (LMP1) mRNA, expressed in nasopharyngeal carcinoma, has been determined. The transcript initiates from heterogeneous start sites within the first terminal repeat (TR) of the viral genome. This region is TATA-less, consistent with heterogeneous starting, but contains multiple GC-rich elements which potentially interact with the Sp1 transcription factor. Expression of the 3.5-kb mRNA was consistently detected in nasopharyngeal carcinoma samples and in additional cell types, including a Burkitt's lymphoma. This is the first identification of an Epstein-Barr virus mRNA containing TR sequence and the first report of the ability of the TR to function as a transcriptional promoter.

Base Sequence↗

PubMed1995

Undifferentiated, nonkeratinizing, and squamous cell carcinoma of the nasopharynx. Variants of Epstein-Barr virus-infected neoplasia.

Nasopharyngeal carcinoma (NPC) samples of distinct histological types, including squamous cell carcinoma (WHO type 1), nonkeratinizing carcinoma (WHO type 2), and undifferentiated carcinoma (WHO type 3), were analyzed for Epstein-Barr virus (EBV) infection and gene expression by using in situ and biochemical techniques. The EBV-encoded RNAs (EBER) were detected in situ in most tumor cells of all three WHO types of NPC. In foci of squamous differentiation and keratinization within less differentiated NPC and throughout the expanse of well differentiated squamous cell carcinoma, EBER expression was less abundant. Latent membrane protein, an EBV-encoded membrane protein, was detected in 72% (36/50) of all NPC and 67% (6/9) of the cases of squamous cell carcinoma. The EBV genomes were present as clonal episomal forms, without detectable linear viral DNA, in all cases of squamous cell carcinoma analyzed. Polymerase chain reaction amplification of cDNA detected EBV transcription for Epstein-Barr nuclear antigen 1, latent membrane proteins 1 and 2, and BamHI A in all samples, indicating that all forms of NPC express the same EBV genes. These results reveal that EBER expression is significantly decreased in areas with squamous differentiation and confirm that all types of NPC, regardless of histological type or differentiation contain clonal episomal EBV genomes, express specific EBV genes and are a clonal expansion of EBV-infected cells.

Base Sequence↗

PubMed1994

Sequence variation in the Epstein-Barr virus latent membrane protein 1.

The sequence of the latent membrane protein 1 (LMP-1) gene was analysed in Epstein-Barr virus (EBV) isolates from specific regions representing both type 1 and type 2 EBV. A predominant strain marked by an XhoI restriction enzyme polymorphism (REP) within the LMP-1 gene has been identified in type 1 EBV in nasopharyngeal carcinoma (NPC) from Southern China. This polymorphism was also present in type 2 EBV in NPC from Alaska. In this study, the sequence of the LMP-1 gene was determined in these samples representing type 1 and type 2 EBV and was compared with the prototype lymphoid strains. Consistent nucleotide variation in the amino terminus of LMP-1 was identified in strains marked by the XhoI REP. These changes were present in both EBV type 1 and type 2 strains. Three types of sequence variation were detected in the carboxy terminus of LMP-1. The LMP-1 sequences differed in the number of an 11 amino acid repeat element. In the prototype EBV type 1 (B95-8) sequence and in the type 1 Raji and type 2 HR-1 strains, the third repeat element contained an insertion of 5 amino acids that were also the first five unique amino acids after the last partial repeat element. The third variation was a deletion of amino acids 343 to 352 of the B95-8 LMP-1. This deletion was detected in the type 1 Chinese EBV strains, but was not detected in the type 2 Alaskan strains although the Chinese and Alaskan strains have nearly identical amino acid changes at the amino terminus. Numerous other amino acid changes were detected in the carboxy terminus which did not cosegregate with either EBV type, amino acid changes in the amino terminus, or specific geographic regions. These data indicate that EBV strains can be distinguished by sequence differences within LMP-1 and that unlike the divergence between type 1 and type 2 EBV in Epstein-Barr nuclear antigen sequences, different EBV types are nearly identical in LMP-1 sequence.

Amino Acid Sequence↗

PubMed1994

Epstein-Barr virus intrastrain recombination in oral hairy leukoplakia.

In laboratory lymphoblastoid cell lines and in natural human infections, Epstein-Barr virus (EBV) strains have been identified by DNA restriction fragment length polymorphisms of the BamHI H fragment. Multiple, heterogeneous BamHI H fragments have been detected in oral hairy leukoplakia (HLP), raising the question of EBV coinfection with multiple strains. To investigate whether the heterogeneous BamHI H fragments represent different EBV strains or recombinant variants of the same strain, EBV DNA from HLP lesions was analyzed to characterize the viral strains and determine the source of possible recombinant variants. Clones of heterogeneous BamHI H fragments from a single HLP lesion were determined to have strain identity on the basis of sequence identity of the EBNA-2 genes. Intrastrain homologous recombination within the IR2 internal repeat region and nonhomologous recombination of other sequences accounted for the heterogeneity of the BamHI H fragments. PCR amplification from additional HLP specimens detected similar recombinant variants. A possible example of site-specific recombination joining the BamHI Y portion of the EBNA-2 gene to sequences within the BamHI S fragment was also detected in multiple HLP specimens. These data indicate that intrastrain recombination during productive replication confounds the use of restriction fragment length polymorphism analysis of the BamHI Y and H fragments to identify EBV strains in HLP. In patients with permissive epithelial EBV infections, EBV strains could be more accurately distinguished by sequence identity or divergence within known regions of genetic strain variation.

Amino Acid Sequence↗

PubMed1994

The Epstein-Barr virus EBNA-2 gene in oral hairy leukoplakia: strain variation, genetic recombination, and transcriptional expression.

Oral hairy leukoplakia (HLP) lesions frequently contain defective Epstein-Barr virus (EBV) genomes with deletions in the EBNA-2 gene that abundantly replicate and persist within the lesion. To characterize these viral strains and recombinant variants, the EBNA-2 gene in EBV DNA from several different HLP biopsy specimens was analyzed. Amplification of EBNA-2 coding sequences by PCR demonstrated the presence in HLP of intact EBNA-2 genes as well as a variety of internally deleted variants of both EBNA-2A and EBNA-2B. Some of the deletion variants evolved within the HLP lesion from intact EBNA-2 genes, while other variants appeared to be transmissible strains that directly infected the lesion. Intrastrain recombination within the HLP lesion also generated variation within the EBNA-2 polyproline region. Cloning and sequencing of HLP cDNA demonstrated transcription from the internally deleted EBNA-2 open reading frame, indicating that these variant genes are expressed in HLP. Comparative analysis of the HLP EBNA-2 sequences confirmed previous findings of EBV coinfection with multiple types and strains. Sequence variation of these wild-type genes demonstrated that EBNA-2A sequences distinguish at least two separate strains and a variety of substrains of EBV type 1. Two of the HLP EBNA-2A sequences contained amino acid changes in a cytotoxic T-cell epitope within an otherwise highly conserved region of the gene. These data indicate that EBV coinfection, strain variation, and recombination within the EBNA-2 gene are common features of HLP and suggest that the expression of internally deleted EBNA-2 variants could contribute to EBV pathogenesis in permissive infection.

Amino Acid Sequence↗

PubMed1994

Alterations of the p53 gene in Epstein-Barr virus-associated immunodeficiency-related lymphomas.

Mutations of the p53 tumor suppressor gene are among the most common genetic alterations found in many different human malignancies, including those of the colon, lung, and breast. Alterations in wild-type p53 lead to loss of the suppressor function and thus contribute to tumorigenesis. The potential role of p53 mutations in a sampling of B-cell lymphomas, the majority of which were associated with Epstein-Barr virus (EBV), was investigated. Twenty-six biopsy specimens from immunocompromised patients, including allograft recipients and patients with AIDS, Wiscott-Aldrich syndrome, and human T-cell leukemia virus type 1 infection, in comparison with three Burkitt lymphomas and four Burkitt lymphoma cell lines were analyzed. Mutation in p53 was detected in all four Burkitt lymphoma cell lines as well as the three Burkitt lymphoma biopsy specimens. In patients with AIDS, 5 of 10 lymphomas were EBV positive, and 1 had a mutation in p53. Mutation in p53 was not detected in 14 EBV-positive lymphomas which arose in transplant recipients. These data indicate that with the exception of Burkitt lymphomas, p53 mutations are not involved in the majority EBV-positive B-cell lymphomas which develop in immunocompromised patients.

Alleles↗

PubMed1993

Epstein-Barr virus (EBV) gene expression in EBV-positive peripheral T-cell lymphomas.

Epstein-Barr virus (EBV) DNA has been detected in peripheral T-cell lymphomas. In this study, analysis of the EBV termini indicated that the infection was clonal and nonpermissive. Analysis of viral expression detected the processed, spliced mRNAs representing EBNA1, LMP1, LMP2, and BamHI A transcripts in all EBV-positive peripheral T-cell lymphomas. The LMP1 protein was detected by immunofluorescence in a single specimen. In contrast, neither the EBNA2 protein nor the spliced EBNA2 mRNA were detected. These data indicate that EBV-infected T-cell lymphomas are clonal expansions of a single EBV-infected cell with a pattern of gene expression which is distinct from that detected in Burkitt's lymphomas or posttransplant lymphomas but similar to viral expression in nasopharyngeal carcinomas.

Antibodies, Monoclonal↗

PubMed1993

Detection of Epstein-Barr virus in human tissues by molecular genetic techniques.

In the past few years, there has been an explosion of new data on the association of Epstein-Barr virus (EBV) with human disease. Many of these discoveries have come as a direct result of the application of DNA technology. The nucleic acid hybridization techniques most commonly used to detect EBV in human tissues include Southern blot analysis, in situ hybridization to viral DNA or RNA, and polymerase chain reaction. An advantage of Southern blotting is the ability to distinguish latent from infectious EBV and to determine the clonality of infected tumors with respect to the structure of the viral terminal repeat sequences. In situ hybridization has the advantage of precise localization of the virus in infected tissues or tumors. Polymerase chain reaction is exquisitely sensitive in detecting viral DNA, perhaps too sensitive for disease-specific purposes given the ubiquitous nature of EBV. Each of these molecular genetic methods of EBV analysis is currently used in research laboratories, while some methods have found their way into routine diagnostic pathology because they are faster, more sensitive, or more informative than previous assays.

Blotting, Southern↗

PubMed1992

Epstein-Barr viral latency and cell immortalization as targets for antisense oligomers.

The approach of using an antisense oligonucleotide to oppose the synthesis of a single selected viral gene product needed to maintain the EBV episome in non-virus-producing cells appears to be promising not only for possible cure of latent viral infection, but also for reversal of EBV-driven cell proliferation. It is also possible that targeting multiple latent viral genes might mount a synergistic effect that would prove to be more efficient at curing latent infection. However, further work is needed to identify the reasons for the variable results that are observed as well as to prove specificity of the inhibitory effects. Finally, we are also working on other assays and methods to screen compounds rapidly.

Antigens, Viral↗

PubMed1992

Coinfection with multiple strains of the Epstein-Barr virus in human immunodeficiency virus-associated hairy leukoplakia.

Epstein-Barr virus DNA was analyzed from specimens of hairy leukoplakia, an oral lesion that occurs in patients infected with the human immunodeficiency virus. The simultaneous presence of both type 1 and type 2 Epstein-Barr virus was demonstrated by Southern blot analysis and polymerase chain reaction assay. Restriction fragment length polymorphisms in the BamHI WYH region and in clones of the EcoRI C region suggested the presence of multiple strains of type 1 and type 2 viruses. The demonstration of multiple variably sized BamHI H fragments on Southern blot analysis and cloning of the EBNA-2 gene coding region also suggested the presence of multiple viral strains or variants coinfecting hairy leukoplakia. Recombination of the viral genome in and around the EBNA-2 gene apparently generated viral variants that replicated efficiently, one of which appeared to increase in abundance in a lesion over time. These data indicate that hairy leukoplakia involves coinfection with multiple strains of replicating Epstein-Barr virus and the endogenous generation of viral variants, some of which have mutations of the EBNA-2 gene.

Antigens, Viral↗

PubMed1992

Epstein-Barr virus integration in human lymphomas and lymphoid cell lines.

BACKGROUND: Epstein-Barr virus (EBV) is maintained as an episome in most infected cells. The presence of fused terminal restriction enzyme fragments distinguishes the circular DNA form from the linear virion form. METHODS: EBV genomic structure was analyzed in 8 lymphoid cell lines and 21 human lymphoma specimens by the Southern blot technique. RESULTS: Evidence of viral integration into host chromosomal DNA was identified in four cell lines. In the Namalwa and BL30-B95.8 cell lines, integration occurred through the terminal repeat (TR) sequences. In the BL41-P3HR1 and BL41-B95.8 cell lines, there was loss of left-end viral genomic sequences, including ori-P sequences required for episome maintenance, implying that integration was required for viral genome persistence. Integration was not detected in four other cell lines (Raji, Daudi, B95.8, and BL30-P3HR1). In 21 EBV-containing human lymphomas, including 18 immunodeficiency-related lymphomas, fused TR sequences were identified without evidence of viral genomic integration. CONCLUSIONS: These findings suggest that, although viral integration is common in Burkitt lymphoma cell lines infected in vitro, integration is not common in human lymphomas that develop in vivo in normal or immunodeficient people.

Adolescent↗

PubMed1992

EBV strain variation: geographical distribution and relation to disease state.

The strains of Epstein-Barr virus (EBV) were characterized in epithelial and lymphoid malignancies from geographic regions with high or low incidence. The predominant strains in nasopharyngeal carcinoma (NPC) from regions with elevated incidence were EBV type 1 in southeast Asia and Mediterranean Africa. In Alaskan Eskimos, a distinct variant of EBV type 2 was found in NPC and carcinoma of the parotid gland. This strain contained polymorphisms characteristic of the Asian EBV type 1. The strains prevalent in southeast Asia and Mediterranean Africa were also found in NPC which developed in caucasian Americans. These variants were not detected in lymphomas which developed in central Africa, Mediterranean Africa, or continental United States. These results suggest that distinct EBV strains predominate in geographic areas with elevated incidence of NPC. The detection of these distinct strains in epithelial tumors from areas of low incidence may reflect an epithelial cell tropism or pathogenicity.

Animals↗

PubMed1992

Consistent transcription of the Epstein-Barr virus LMP2 gene in nasopharyngeal carcinoma.

Two species of the Epstein-Barr virus-encoded latent membrane protein 2, LMP2A and LMP2B, are generated by alternative splicing, each species having a distinct first exon. LMP2 transcription in undifferentiated nasopharyngeal carcinoma (NPC), which is consistently associated with the Epstein-Barr virus, was investigated. Fifteen NPC specimens were analyzed by Northern (RNA) blot and RNA-based polymerase chain reaction; the LMP2A transcript was present in all specimens except one. In some specimens the LMP2B transcript was also detected. Sequence analysis of LMP2 cDNAs obtained from two NPC specimens revealed four mutations in exon 1 of the LMP2A transcript, which were present in both tumors and which resulted in nonconservative amino acid changes. These data suggest that the LMP2 expressed in NPC is distinct from that which is expressed in lymphoid cells.

Amino Acid Sequence↗

PubMed1992

Alterations of the p53 gene in nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is a malignancy which is consistently associated with the Epstein-Barr virus (EBV). The structure of the EBV genome in NPC suggests that NPC is a clonal proliferation of epithelial cells which emerges after EBV infection. The disease develops with high incidence in specific populations in discrete geographic locations, implicating possible genetic or environmental cofactors. Mutations of the p53 gene are among the most frequent genetic changes found in a large variety of human tumors. Mutations in p53 have been shown to abrogate the suppressor function of wild-type p53 and thus contribute to the transformed phenotype. To determine if mutation in p53 participates in the development of the malignant clone in NPC, the structure and sequence of p53 in 42 primary, metastatic, and nude mouse-passaged NPC specimens was analyzed. A high frequency (6 of 9) of mutations was detected in the nude mouse-passaged tumors, while only 2 of 15 metastatic and 0 of the 18 primary tumors harbored mutant p53. The p53 mutations included single-point mutations and more extensive changes such as frame shifts, deletion, duplication, or complete loss of coding sequences. These data indicate that alterations of the p53 gene are unlikely to be involved in the initial genetic events leading to the clonal outgrowth in NPC. However, although it is a rare NPC which can be established in nude mice, this growth advantage appears to be conferred on tumors bearing a mutant p53.

Animals↗

PubMed1992

Epstein-Barr virus and nasopharyngeal carcinoma.

Nasopharyngeal carcinoma, an epithelial tumor which is characterized by marked geographic and population differences in incidence, is consistently associated with the Epstein-Barr virus (EBV). Within the tumor, the EBV DNA is homogeneous and clonal with regard to repeat sequences suggesting that the tumor is also clonal. Expression of specific viral mRNAs or gene products are consistently detected within all of the tumor cells. These data suggest that EBV is an essential component in the development of nasopharyngeal carcinoma. Genetic or environmental co-factors may influence the ability of the virus to express these genes in infected epithelial tissue or may contribute to clonal predominance.

Cells, Cultured↗

PubMed1992

Epstein-Barr virus infection in nasopharyngeal carcinoma.

Nasopharyngeal carcinoma develops with extremely high incidence in discrete populations and geographic locations. It is consistently associated with the ubiquitous Epstein-Barr herpesvirus (EBV). The structure of EBV DNA indicates that the tumor is a clonal proliferation that developed subsequent to EBV infection. Specific viral genes are consistently expressed within all cells of the tumor. This consistent expression may indicate that the viral gene products are required for tumor growth. Genetic or environmental factors may affect the expression of these critical viral genes or cellular genes and contribute to tumor progression.

Animals↗

PubMed1991

A transformation-incompetent, nuclear antigen 2-deleted Epstein-Barr virus associated with replicative infection.

Epstein-Barr virus (EBV) obtained directly from the oropharynx was used to detect viral DNA deleted for the EBV nuclear antigen 2 (EBNA2)-encoding gene that is essential for lymphocyte transformation. By polymerase chain reaction analysis, the deletion was found in virus from 5 of 33 healthy adult donors and 11 of 12 patients with concurrent human immunodeficiency virus infection. Lymphoblastoid cell lines that produce standard transforming EBV also harbored EBNA2-deleted virus in cells permissive of EBV replication. In vitro infectivity studies indicated that the DNA is packaged and transmissible, with biologic properties similar to those of a laboratory mutant, P3HR-1, which also lacks the EBNA2 gene. These findings, obtained from productively infected cell systems, provide evidence for the existence in nature of a transformation-incompetent EBV variant that may facilitate EBV persistence and the emergence of reactivation diseases.

Antigens, Viral↗