No evidence for differences in the Epstein-Barr virus genome carried in Burkitt lymphoma cells and nonmalignant lymphoblastoid cells from the same patients

Rapid determination of Epstein-Barr virus latent or lytic infection in single human cells using in situ hybridization

Epstein-Barr (EBV) virus is associated with malignancies such as lymphoma and carcinoma. Infection of cells with EBV may result in either lytic infection with production of viral particles, characterized by the presence of linear DNA forms, or latent infection, characterized by either episomal or integrated DNA forms. To examine whether the different lytic and latent EBV DNA forms can reliably be distinguished in single human cells, in situ hybridization was performed in EBV-positive cell lines. Immunocytochemistry and Southern blot analysis were performed supplementary to in situ hybridization. In latent infection, three in situ hybridization patterns were observed: large-disperse (episomal), small-punctate (integrated) and combined (both), signal types 1, 2 and 3 respectively. These were associated with expression of latent membrane protein 1, but not with Z fragment of Epstein-Barr replication activator or viral capsid antigen. In lytic infection, three additional in situ hybridization patterns were observed: nuclear membrane associated, bubble (filling up the nucleus) and spillover (covering the lysed cells) signals types 4, 5 and 6 respectively. Signal types 4 and 5 were associated with expression of latent membrane protein 1 and Z fragment of Epstein-Barr replication activator but not viral capsid antigen, whereas type 6 was associated with expression of viral capsid antigen only. Southern blot analysis confirmed these results; however, low copy numbers of integrated virus were often missed by Southern blot, confirming that in situ hybridization is more sensitive in determining the presence of all types of EBV DNA. In situ hybridization may prove useful in rapidly screening large series of tissue microarrays and other clinical specimens for the presence of lytic or latent EBV.

A strategy for precision of genotyping of Epstein-Barr virus by polymerase chain reaction: application for studying Hodgkin's lymphoma

Previous studies on the genotyping of Epstein-Barr virus (EBV) have been based on the analysis of a single gene locus. The assignment of genotype of an isolate could easily be over-looked with this assay. Our strategy for precision of EBV genotyping has exploited the existence of two families of EBV strains (type A and B) that can be distinguished at three divergent gene loci (EBNA-2, EBNA-3C, and EBER). To precisely determine the genotype of EBV in Hodgkin's disease (HD), we designed primers and simultaneously analysed these three gene loci that distinguish type A and B viruses by the polymerase chain reaction (PCR) technique. The primers designed to amplify these three gene loci encompass either type-specific deletion sequences (EBNA-2 and EBNA-3C) or type-specific point mutations (EBER) that identify the virus strain based on the sizes of PCR-amplified products or the mobility shifts in single-strand conformation polymorphism (SSCP) analysis. The locations of point mutations were identified by direct sequencing of the PCR-amplified DNA. Fifteen EBV-infected cell lines were analysed and a good correlation between EBNA-2 and EBNA-3C typing results was found. In contrast, approximately 33% of the cell lines analysed maintained type A sequences in EBNA-2 and EBNA-3C genes while carrying type B sequences in the EBER region. Data obtained from analysis of cell lines served as a reference for studying HD samples. EBV DNA was detected in about 70% of HD. Among the EBV-positive samples, 56% were associated with type A virus, 13% with type B, and 31% with dual viral sequences.(ABSTRACT TRUNCATED AT 250 WORDS)

Genotypic analysis of Epstein-Barr virus associated with nasopharyngeal carcinoma of Japanese patients

Types and certain genetic markers were studied for Epstein-Barr virus present in 10 specimens of nasopharyngeal carcinoma (NPC) from Japanese patients. The type 1 virus was predominant in our NPC specimens, as in the general Japanese population, and the type 2 virus was found only in one NPC specimen. The type C variant, which lacks the BamHI site between the BamHI-W1* and -I1* regions, appeared to be common among Japanese strains as in those in Southern China. The type f variant which has an extra BamHI site in the BamHI-F region and has been shown to be strongly associated with NPC in Southern China was found in only one NPC specimen. This virus strain was also the only type 2 virus among our specimens. The present study, therefore, does not show any specific association of the type f variant with NPC in Japan.

Down-regulation of integrated Epstein-Barr virus nuclear antigen 1 and 2 genes in a Burkitt lymphoma cell line after somatic cell fusion with autologous EBV-immortalized lymphoblastoid cells

Epstein Barr virus (EBV) latent gene expression was analyzed in somatic cell hybrids between an EBV-positive Burkitt lymphoma (BL) cell line (BL 60) and an autologous EBV-immortalized lymphoblastoid cell line (LCL, IARC 277). The EBV genomes carried by the parental cell lines differ in sequence and in their physical state. The BL 60 EBV genome is integrated into the host cell genome whereas the LCL IARC 277 carries exclusively episomal EBV molecules. The hybrid cells contain both EBV genomes and display the differentiation phenotype of the parental LCL with regard to growth characteristics and cell-surface antigen expression in vitro and in vivo. While the EBNA 1 and EBNA 2 gene expression of the LCL-derived EBV is maintained in these hybrid cells, the BL-60-derived EBNA 1 and EBNA 2 genes are transcriptionally down-regulated. Mapping of the genomic region surrounding the latent Cp promoter of the BL-60-derived EBV revealed an extensive deletion upstream of the Cp promoter including the enhancer element in the ori P region, the origin of latent viral replication (ori P), the coding sequences for the EBV latent membrane protein (LMP) and the EBV terminal protein (TP), and suggested that one viral-cellular junction sequence is located near the Cp promoter. Integration of EBV into the host cell genome together with the extensive deletion might be causally related with the altered latent gene expression pattern after introduction of a lymphoblastoid host-cell background by somatic cell fusion. Down-regulation of the BL-60-derived EBNA genes could be due to loss of regulatory sequences in the BL-derived EBV necessary for EBNA 1 and EBNA 2 transcription in the lymphoblastoid hybrid cells, but not in the parental BL cells.

Differential expression of Epstein Barr viral transcripts for two proteins (TP1 and LMP) in lymphocyte and epithelial cells

Studies presented here show that some functions of the human herpesvirus, EBV, may be transcriptionally differentially expressed in two cell types which carry the same (C15) isolate of this virus. Of the 'latent' viral functions investigated, only one (TP2) of the episomally-specific genes that encode terminal proteins (TP1 and TP2) is found to be expressed in the C15 epithelial cell tumour environment, whereas both are transcribed--as different, but related, messengers--in a B-cell line generated with virus from the C15 tumour. The other gene investigated is that for latent membrane protein (LMP), which is found in the same region of the EBV genome but on the opposite strand. This gene, apparently transcriptionally silent in B-cell (Burkitt's) lymphomas, is expressed in the C15 epithelial tumour, as well as in other nasopharyngeal carcinomas investigated. Promoter usage in the carcinomas and B-cells appears, in some cases at least, to be cell-type specific. Expression may also be governed by methylation since a chromosomally silent region in the carcinoma (that encompassing TP1) is highly methylated on CpG residues, whereas the active region (encoding TP2 and LMP) is virtually free of such methylation. Our data suggest that there may be selective transcriptional regulation of EBV genes in the two types of cells investigated. Thus, it may be unnecessary to invoke different virus genotypes to account for the two distinct malignancies--Burkitt's lymphoma and nasopharyngeal carcinoma--associated with EBV.

Chronic fatigue syndrome: I. Epstein-Barr virus immune response and molecular epidemiology

Patients with chronic fatigue syndrome were compared to healthy seropositive control subjects in an open study and a case-control study analyzing spontaneous transformation rates of peripheral blood lymphocytes, EBV viral genome characteristics as determined by DNA restriction fragment polymorphisms, and antibody production by Western blot analysis. Thirty percent of patients versus 8% of control subjects underwent spontaneous transformation in the two studies. Viral genome patterns were overall similar to one another, with polymorphisms frequently present in BamHI B', K, H, and Y fragments. Only one line was found with the EBNA-2B genotype. Nineteen lines were found to contain viral DNA in the linear form suggesting active lytic replication. Western blot studies suggested that ill subjects made antibodies to lytic proteins more frequently than did healthy control subjects. Lack of control of EBV outgrowth in vitro is correlated with antibody evidence of active infection in vivo in some patients with chronic fatigue syndrome.

EBV genome and immunoglobulin gene rearrangement in the differential diagnosis of nasopharyngeal carcinoma and lymphoma

Head and neck tumors include nasopharyngeal carcinoma (NPC) and lymphoma. The differential diagnosis of these tumors is based on histology, immunocytochemical staining, and EBV serology. In rare cases it might be difficult to distinguish between NPC and lymphoma in HE section or biopsies. DNA hybridization with cloned EBV and human immunoglobulin gene fragments allows the detection of EBV-related sequences and immunoglobulin gene rearrangements. The presence of EBV genome supports the diagnosis of NPC or EBV related BL, while rearrangement of immunoglobulin genes points to B-cell lymphoma. The diagnosis in 11 patients suspected of head and neck tumors was carried out by hybridization of DNA extracted from the tumors and assayed with cloned EBV and IgHCJ DNA probes. One patient proved to have EBV-associated BL based on positive hybridization with EBV probes and immunoglobulin rearrangement, presenting a unique hybridization with cloned EBV DNA BamHI W fragment, with bands of 3.2 and 3.9 kb. BL was confirmed in this patient by demonstration of c-myc rearrangement. A second patient was negative in hybridization with EBV, and positive for immunoglobulin rearrangement, and therefore was diagnosed as having B-cell lymphoma. In seven patients NPC was confirmed by hybridization with EBV-DNA probes. In two patients, both NPC and B-cell lymphomas were excluded.

Demonstration of Epstein-Barr viral DNA in formalin-fixed, paraffin-embedded samples of Hodgkin's disease

The presence of Epstein-Barr virus (EBV) DNA in formalin-fixed, paraffin-embedded samples of Hodgkin's disease (HD) was investigated by Southern blot hybridization using a specific EBV Bam H1W fragment probe. DNA from 16 samples of HD in children and young adults was compared with that from ten samples in adults older than 45 years. A further eight cases of DNA extracted from fresh samples of HD were also studied, in order to compare the results obtained with fresh and fixed tissue samples. Hybridization was demonstrated in 15 of the 34 cases of HD studied in contrast to 3 or the 34 control specimens of non-Hodgkin's lymphoma, non-neoplastic lymph nodes, and carcinomas. No differences between the two age groups compared were found. The results of this study suggest that there is a definite association between EBV and HD, although the exact nature of this association remains to be established. It has also been shown that DNA of sufficient quality for the detection of EBV DNA can be extracted from formalin-fixed, paraffin-embedded material, and that comparable results can be obtained using DNA extracted from fresh and fixed tissue.

Two families of sequences in the small RNA-encoding region of Epstein-Barr virus (EBV) correlate with EBV types A and B

DNA sequence analysis was carried out on the 1-kilobase SacI-EcoRI region of the EcoRI J fragment of four strains of Epstein-Barr virus (EBV) (MABA, P3HR-1, FF41, and NPC-5), and the sequences were compared with the prototype sequence from strain B95-8. Ten single-base changes which grouped the strains into two families (1 and 2) were found. Restriction endonuclease polymorphisms predicted from the sequences were used to classify the EBV DNA from a further 26 EBV-positive cell lines into these two families. The EBNA-2 types (A or B) of the strains were found to correlate with the J region type; EBNA-2 type A DNA regularly contained J region sequence type 1, while EBNA-2 type B DNA generally carried J region sequence type 2. These data are consistent with the notion of there being two distinct families of EBV with discrete, conserved differences in DNA sequence.

Genetic polymorphism of natural Epstein-Barr virus isolates from infectious mononucleosis patients and healthy carriers

We analyzed Epstein-Barr virus (EBV) genomes from lymphoblastoid cell lines isolated from patients with infectious mononucleosis and from healthy subjects from California, Hawaii, and Hong Kong between 1970 and 1987. Using genetic polymorphism as epidemiological markers, we found that several genotypes of EBV cocirculate in a community and that although most EBV strains isolated from California and Southern China may be differentiated genotypically, there was no specific association between genotype and disease or time of isolation.

Epstein-Barr virus and human diseases: recent advances in diagnosis

Since the discovery of Epstein-Barr virus (EBV) from a cultured Burkitt's lymphoma cell line in 1964, the virus has been associated with Burkitt's lymphoma, nasopharyngeal carcinoma, and infectious mononucleosis. During the recent decade, EBV has been etiologically implicated in a broad spectrum of human diseases. The precise role of this virus in these diseases is not well understood, but clearly, defective immunosurveillance against the virus may permit an uncontrolled proliferation of EBV-infected cells. As a result, a growing number of cases of EBV-associated B-cell proliferative diseases or lymphoma have been noted in patients with primary and acquired immunodeficiencies. These lymphoproliferative diseases and others, such as chronic mononucleosis syndrome, are leading to new areas of investigation which are providing information regarding the pathogenetic mechanisms of EBV-induced diseases. The early accurate diagnosis of EBV infection can be achieved by performing EBV-specific serology, detecting for EBV-determined nuclear antigen in tissues, establishing spontaneous lymphoid cell lines, and using molecular hybridization techniques for demonstrating the presence of viral genome in affected lesions.

Phenotype versus immunoglobulin and T-cell receptor genotype of Hodgkin-derived cell lines: activation of immature lymphoid cells in Hodgkin's disease

Three Hodgkin-derived cell lines (L428, L540, and CO) were studied for rearrangements and expression of immunoglobulin and T-cell receptor genes, and their genotype was compared to the phenotype. As far as the genotype is concerned, all 3 cell lines have characteristics of lymphoid cells; L428 of B, and L540 and CO of T-cell origin. L428 cells have one Ig heavy chain allele rearranged to C gamma and transcribed into RNA, while the second is deleted. Furthermore, L428 cells show an unusual immunoglobulin kappa light chain gene rearrangement involving deletion of the kappa constant gene in one allele, while the remaining kappa and lambda loci are in germline configuration. L540 and CO have, in contrast to L428 cells, the immunoglobulin genes in germline and T-cell receptor genes rearranged. The T-cell receptor beta and gamma genes are rearranged in both L540 and CO, whereas a rearrangement in the alpha locus was detected in L540 cells only. RNA of the size of functional beta chain transcripts was found in CO cells and of the size of functional alpha chain transcripts in L540 cells. All 3 cell lines are classified as immature lymphoid cells with respect to the limited expression of B- and T-cell antigens, respectively, and to the incomplete expression of their antigen receptor. The immaturity of lymphoid differentiation contrasts with the expression of activation antigens, i.e. Ki-1, Ki-24, HLA-DR, and IL-2 receptor. The immaturity of the cells excludes the possibility that the cells were activated along the physiological pathway, i.e. by interaction of the cell with antigen. The results obtained on the cell lines are in accordance with in vivo studies and suggest that Hodgkin and Sternberg-Reed cells are immature lymphoid cells which are activated by a still unknown mechanism.

Characterization of a second Epstein-Barr virus-determined nuclear antigen associated with the BamHI WYH region of EBV DNA

The Epstein-Barr virus-determined nuclear antigen (EBNA) is the only known virally-determined component that is regularly associated with EBV-transformed cells. A main component of EBNA, herein designated EBNA-1, has been conclusively localized to the BamHI K fragment of the viral genome. EBNA-1 is present in all EBV-carrying cell lines so far studied. Our current study deals with a second component. We have found that the EBNA reaction detected by anti-complement immunofluorescence (ACIF) in Burkitt lymphoma lines Daudi, Jijoye, and P3HR-1 could be completely removed by preabsorption of sera with any one of these 3 lines, when tested against any other of them. The same absorbed sera still gave a brilliant nuclear staining against other EBV-carrying lines, e.g. Raji or B95-8. The 3 lines in the first category carry EBV genomes that have deletions in the BamHI WYH region of the EBV genome. This region is intact in the second group of lines. This result is interpreted as showing the existence of 2 different ACIF-stainable EBV-determined nuclear antigens, one of which is associated with the BamHI WYH region. We designate this antigen as EBNA-2. We found that the two different EBNAs are different with regard to their association with metaphase chromosomes. In lines positive for both EBNA subtypes, metaphase chromosomes gave brilliant EBNA-1 staining, but could not be stained for EBNA-2, indicating differences in chromatin association of the two EBNAs. An 86 kd polypeptide was identified by immunoblotting of DNA-binding proteins from EBV-transformed lymphoid cell lines. EBV-specificity of the polypeptide was demonstrated by the presence of antibodies against this polypeptide in antisera from a population of EBV-seropositive donors, but not from seronegative donors, by the presence of the polypeptide itself in EBV-carrying but not in EBV-negative cell lines and by the appearance of antibodies against this polypeptide during the course of infectious mononucleosis (IM). The polypeptide was absent from the EBV-carrying P3HR-1, Daudi and Jijoye cell lines, which suggested that it may be encoded by the BamHI WYH region that is deleted from the viral substrains carried by these lines.