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

From Burkitt's lymphoma to chronic active Epstein-Barr virus (EBV) infection: an expanding spectrum of EBV-associated diseases

Epstein-Barr virus (FBV) is one of 8 known human herpesviruses. EBV infection usually occurs in early childhood and is subclinical. However, primary infection in adolescence or adulthood causes infectious mononucleosis in approximately half of infected individuals. Recently, the spectrum of human diseases associated with EBV injection has increased, primarily due to methodological advances in EBV detection. Initially, EBV was isolated from a cultured Burkitt lymphoma cell line, and has been felt to be etiologically linked to the development of Burkitt lymphoma, as well as other human malignancies. This review mainly focuses on pathogenetic mechanisms, many of which remain enigmatic, for the various human diseases, which are considered to be associated with EBV injection.

HV(MNE), a novel lymphocryptovirus related to Epstein-Barr virus, induces lymphoma in New Zealand White rabbits

HV(MNE) is a novel Epstein-Barr (EBV)-like virus isolated from a Macaca nemestrina with CD8(+) T-cell mycosis fungoides-cutaneous T-cell lymphoma. Here it is demonstrated that intravenous inoculation of irradiated HV(MNE)-infected T cells or cell-free virus from the J94356(PBMC) cell line in New Zealand White rabbits results in seroconversion to the viral capsid antigen (VCA) of EBV; all animals that seroconverted to VCA developed malignant lymphoma within months of inoculation. In contrast, control rabbits, inoculated with heat-inactivated culture supernatants from the same cell line, failed to seroconvert to VCA and did not develop disease. Disseminated lymphoma cells of mixed origin were detected in most vital organs, including the spleen, liver, lungs, kidneys, and heart of the affected rabbits. Neoplastic infiltrates were also observed in lymph nodes, thymus, skin, and subcutaneous tissues. HV(MNE) DNA and EBV-like RNA expression was demonstrated in the lymphomatous organs and in 2 transformed T-cell lines, one established from the lymph node and the other from the blood of the 2 lymphomatous animals. Analysis of one of these T-cell lines demonstrated the persistence of HV(MNE) DNA, expression of an LMP1-like protein, and acquisition of interleukin-2 independence, and constitutive activation of the Jak/STAT pathway. Thus, HV(MNE) in rabbits provides a valuable animal model for human T-cell lymphoma whereby genetic determinants for T-cell transformation by this EBV-like animal virus can be studied.

Case-control study on concentrations of organohalogen compounds and titers of antibodies to Epstein-Barr virus antigens in the etiology of non-Hodgkin lymphoma

A rapid increase in incidence of non-Hodgkin lymphoma (NHL) has been reported from many countries. Exposure to certain pesticides and organochlorines has been shown to be risk factors. Epstein-Barr virus (EBV) is a human herpesvirus that has been associated with some subgroups of NHL, such as Burkitt lymphoma and lymphomas related to severe immunosuppression. In this study, we measured lipid adjusted blood concentrations of 36 congeners of polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyl-dichloroethylene (p,p'-DDE), hexachlorobenzene (HCB), four different subgroups of chlordanes (trans-nonachlordane, cis-nonachlordane, MC6 and oxychlordane) and 2,2',4,4'-tetrabrominated diphenyl ether (TBDE) in incident cases of NHL and controls from the general population. Titers of antibodies to the Epstein-Barr early antigen (EA) were correlated to concentrations of organochlorines. We found a significant difference in lipid adjusted blood concentrations of total PCBs and TBDE between cases and controls. Titers of antibodies to EA IgG > 80 were correlated to an increased risk for NHL with odds ratio (OR) = 1.9, 95% confidence interval (CI) =0.94-3.8. This risk was further increased in those with a level above the median value of "sum of PCBs" (OR=4.0, CI=1.2-14), HCB (OR=5.3, CI=1.6-19), sum of chlordanes (OR=4.0, CI=1.2-14) and TBDE (OR=21, CI=4.6-124), suggesting an interaction between EBV and a higher concentration of these chemicals. Also for the "sum of immunotoxic PCBs" increased risk was found in that group (OR=6.4, CI=1.9-24). Subdivision of NHL in histological types yielded highest risks for low-grade B-cell NHL.

Lymphoepithelioma-like cholangiocarcinoma: an Epstein-Barr virus-associated tumor

Epstein-Barr virus (EBV) has been linked to carcinomas of several body sites, especially of the nasopharynx, salivary gland, lung, and stomach. We present five cases of lymphoepithelioma-like cholangiocarcinoma, including one that had been previously reported. Two patients were men and three were women. Their ages ranged from 42 to 66 years. Histologically, all five tumors were composed of variable proportions of undifferentiated epithelial cells and glandular components in a lymphocyte-rich stroma. EBV was detected in all five tumors by in situ hybridization for EBER-1 in both lymphoepithelioma-like carcinoma (LELC) and glandular parts, but not in 36 cases of cholangiocarcinoma without the LELC component. Taken together, these observations indicate that lymphoepithelioma-like cholangiocarcinoma is strongly linked to EBV. The LELC type of cholangiocarcinoma, like LELC of other body sites, may be more common in areas with endemic EBV infection.

Inhibition of cell growth and Epstein-Barr virus reactivation by CD40 stimulation in Epstein-Barr virus-transformed B cells

The CD40 molecule plays important roles in B cell activation, proliferation, and immunoglobulin (Ig) class switching. In Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCL), CD40 mediates growth inhibition and EBV reactivation via the CD40 signaling pathways. CD40 cross-linking with a monoclonal antibody arrests cell growth in G1 and induces expression of p27kip1 cyclin-dependent kinase inhibitor. CD40 cross-linking also induces EBV reactivation, as detected by the induction of EBV-specific early antigen, immediate early BZLF1 RNA, and its protein product ZEBRA. These results support hypotheses that the proliferation of EBV-infected B cells in vivo can be inhibited by interactions with the CD40 ligand on activated helper T cells, and latent EBV is reactivated via the signaling pathways controlled by CD40 interactions.

Epstein-Barr virus associated B-cell lymphoma of brain developing in myelodysplastic syndrome with c-kit mutation (Try-557 -->stop)

The first case of B-cell lymphoma of brain in a patient with myelodysplastic syndrome (MDS) was reported. A 68-year-old man was admitted because of anemia, fever, and thrombocytopenia and was diagnosed as having MDS (refractory anemia with excess of blasts) on the basis of the findings of bone marrow aspiration and chromosomal analysis. The patient was followed up without chemotherapy, but a brain tumor appeared after 3 years. Histologic and immunohistologic examinations revealed diffuse large B-cell lymphoma. Mutations of the c-kit proto-oncogene (stem cell factor receptor) and the p53 tumor-suppressor gene were examined in the MDS lesion and malignant lymphoma (ML) by the polymerase chain reaction-single-strand conformational polymorphism (PCR-SSCP) method followed by direct sequencing. The p53 mutation was not found in either MDS or ML, but a nonsense mutation (Try-557 --> stop) in exon 11 of the c-kit, which might lead to dysfunction of tyrosine kinase activity, was detected in MDS. This is the first report of c-kit mutation in MDS. Epstein-Barr virus (EBV) genome was demonstrated in the nucleus of brain ML cells by in situ hybridization with EBV-encoded RNA-1 probe. Immunohistochemistry showed that the tumor cells expressed latent infection gene products, including EBV nuclear antigen-2 and latent membrane protein-1. This pattern of latent gene expression was Lat III, which is usually found in malignant lymphomas developing in immunocompromised hosts. These findings suggest that a profound pancytopenia in MDS resulted in an immunodeficient condition, after which EBV-positive B-cell lymphoma of brain developed.

Haematological associations of Epstein-Barr virus infection

Epstein-Barr virus (EBV) is one of eight human herpesviruses and is ubiquitous. Primary infection with EBV in childhood is generally silent, but often causes overt diseases such as infectious mononucleosis (IM) and lymphoproliferative disorders (LPD). The latter occurs in immunologically compromised individuals. Historically, EBV has been thought to be aetiologically linked to human malignancies such as EBV genome-positive Burkitt's lymphoma (BL) and nasopharyngeal carcinoma (NPC). Furthermore, studies using recent developments in molecular and immunological diagnostic approaches have suggested that this virus has a causative role in a spectrum of human diseases of previously unknown pathogenesis, including chronic active EBV infection syndrome (CAEBV), EBV-related haemophagocytic lymphohistiocytosis (HLH), and certain disorders such as EBV genome-positive T-cell lymphoma, natural killer (NK) cell leukaemia/lymphoma, Hodgkin's disease (HD) and gastric carcinoma. This chapter reviews recent progress regarding EBV-associated diseases.

Concentrations of organochlorines related to titers to Epstein-Barr virus early antigen IgG as risk factors for hairy cell leukemia

Hairy cell leukemia (HCL) is a rare chronic B-cell malignancy that, according to modern classifications, is a subgroup of non-Hodgkin lymphomas (NHLs). A rapid increase in incidence of NHL has been reported in many countries. The reasons for this increase are largely unknown, but exposure to organochlorines has been suggested as a risk factor. Epstein-Barr virus is a human herpesvirus that has been associated with certain subgroups of NHL. In this study, we measured lipid adjusted blood concentrations (in nanogram per gram) of 36 congeners of polychlorinated biphenyls (PCBs), p, p'-dichlorodiphenyldichloroethylene (p,p'-DDE), hexachlorobenzene (HCB), and four subgroups of chlordanes (trans-nonachlor, cis-nonachlor, MC6, and oxychlordane) in incident cases of HCL and controls from the general population. We obtained results on organochlorines and antibodies for 54 cases and 54 controls. Titers of antibodies to the Epstein-Barr early antigen and Epstein-Barr nuclear antigen, measured as P107, were correlated to concentrations of organochlorines to evaluate the possibility of an interaction between these factors in the pathogenesis of HCL. We found no significant difference in lipid-adjusted blood concentrations of total PCBs, p,p'-DDE, HCB, or the sum of the chlordanes between cases and controls. Titers of antibodies to Epstein-Barr early antigen IgG [Greater and equal to] 40 were correlated to an increased risk for HCL. This risk was further increased in those with a level above the median value of p,p'-DDE, HCB, or the sum of the chlordanes, suggesting an interaction between Epstein-Barr virus and a higher concentration of these chemicals. We also found increased risk for the sum of immunotoxic PCB group.

Elevated serum transforming growth factor beta1 levels in Epstein-Barr virus-associated diseases and their correlation with virus-specific immunoglobulin A (IgA) and IgM

Transforming growth factor beta (TGF-beta) is an immunosuppressive cytokine which can induce immunoglobulin A (IgA) switch and Epstein-Barr virus (EBV) replication in latently infected cells. Here we report elevated serum levels of TGF-beta in various EBV-associated diseases correlating positively with EBV-specific IgA titers and negatively with IgM titers, suggesting a role for this cytokine in the pathogenesis of these diseases.

Atypical Lymphoproliferative Diseases

This review addresses the clinical presentation, pathology, and therapy of several uncommon lymphoid proliferations. Because these lymphoproliferations span the characteristics of reactive polymorphous proliferations to clonal malignant neoplasms, they are often difficult to diagnose and treat effectively.

In Section I, Dr. Greiner describes the pathology of the spectrum of atypical lymphoid disorders including Castleman's disease, angioimmunoblastic lymphadenopathy, lymphadenopathy in autoimmune diseases, posttransplant lymphoproliferative disorders, and X-linked lymphoproliferative disorder. The relationship to Epstein-Barr virus (EBV) and human herpsesvirus-8 (HHV-8) is discussed, and molecular diagnostic assays and principles for obtaining proper diagnostic evaluation are emphasized.

In Section II, Dr. Armitage presents a practical approach to the management of Castleman's disease. The discussion includes the importance of confirmation of the histological diagnosis and careful staging evaluation, therapeutic options, and the increased risks for infection and lymphoma. The appropriate roles of surgical excision, corticosteroids, and combination chemotherapy are addressed along with alternative strategies such as anti-interleukin-6 and bone marrow transplantation.

In Section III, Dr. Gross reviews the treatment of EBV-associated lymphoproliferative disorders in primary immunodeficiencies and in post-transplant patients. He gives an update on the recent molecular discoveries in X-linked lymphoproliferative disorder. Preliminary results of a phase II trial of low-dose cyclophosphamide in posttransplant lymphoproliferative disorders and the use of GM-CSF as preemptive therapy are presented.

Absence of Epstein-Barr virus (EBV) in intrahepatic cholangiocarcinoma confirmed by lack of EBV-coded nuclear RNA and latent membrane protein-1

AIMS

Studies are disclosing that Epstein-Barr virus (EBV) is involved in the aetiology of various neoplasms including undifferentiated carcinomas of the aerodigestive tract. The aetiology of intrahepatic cholangiocarcinoma (ICC), a malignant neoplasm arising from intrahepatic biliary epithelia, has yet to be fully evaluated. To date, two cases of EBV-related ICC have been reported, and they presented foci of lymphoepitheliomatous undifferentiated carcinoma components.

METHODS AND RESULTS

To determine whether EBV is commonly involved in the developments of ICC, we performed in-situ hybridization and immunohistochemistry for EBV in 215 cases of ICC in Japan, using a probe against EBV-coded nuclear RNA (EBER) and a specific antibody against latent membrane protein-1 (LMP-1), respectively. We did not detect EBV-infected carcinoma cells in any of the ICC cases examined. No lymphoepitheliomatous undifferentiated carcinoma components were found either.

CONCLUSION

The results suggest that EBV infection is unlikely to be involved in the pathogenesis of ICC.

Atypical Lymphoproliferative Diseases

This review addresses the clinical presentation, pathology, and therapy of several uncommon lymphoid proliferations. Because these lymphoproliferations span the characteristics of reactive polymorphous proliferations to clonal malignant neoplasms, they are often difficult to diagnose and treat effectively.

In Section I, Dr. Greiner describes the pathology of the spectrum of atypical lymphoid disorders including Castleman's disease, angioimmunoblastic lymphadenopathy, lymphadenopathy in autoimmune diseases, posttransplant lymphoproliferative disorders, and X-linked lymphoproliferative disorder. The relationship to Epstein-Barr virus (EBV) and human herpsesvirus-8 (HHV-8) is discussed, and molecular diagnostic assays and principles for obtaining proper diagnostic evaluation are emphasized.

In Section II, Dr. Armitage presents a practical approach to the management of Castleman's disease. The discussion includes the importance of confirmation of the histological diagnosis and careful staging evaluation, therapeutic options, and the increased risks for infection and lymphoma. The appropriate roles of surgical excision, corticosteroids, and combination chemotherapy are addressed along with alternative strategies such as anti-interleukin-6 and bone marrow transplantation.

In Section III, Dr. Gross reviews the treatment of EBV-associated lymphoproliferative disorders in primary immunodeficiencies and in post-transplant patients. He gives an update on the recent molecular discoveries in X-linked lymphoproliferative disorder. Preliminary results of a phase II trial of low-dose cyclophosphamide in posttransplant lymphoproliferative disorders and the use of GM-CSF as preemptive therapy are presented.

Epstein-Barr virus and cytomegalovirus in relation to testicular-cancer risk: a nested case-control study

An infectious etiology of testicular cancer has been suggested. We have evaluated seroreactivity against cytomegalovirus (CMV) and Epstein-Barr virus (EBV) in relation to testicular-cancer risk in a case-control study, nested within a cohort of prospectively collected serum specimens from 293,692 individuals. For each of 81 cases of testicular cancer identified, 3 controls were randomly selected from the cohort. Serum IgG antibody titers against CMV and EBV were determined using enzyme-linked immunosorbent assays (ELISAs) and immunofluorescence methods. Odds ratios (OR) were obtained from conditional logistic-regression models. No association was found between CMV positivity and testicular cancer overall (OR = 1.08; 95% confidence interval 0.60-1.94); risk for testicular seminoma was increased among CMV seropositive [OR = 1.70 (0.80-3.59)], whereas seropositivity was associated with decreased risk for testicular non-seminoma [OR = 0.54 (0.19-1.56)] (p for heterogeneity, 0.09). For EBV, the risk for testicular cancer was increased among individuals seropositive for viral capsid antigen (VCA) [OR = 2.74 (0.62-12.12)]. The results lend some support to the hypothesis of an infectious etiology, and we propose that future studies should take into account age at infection.

Functional analysis of different LMP1 proteins isolated from Epstein-Barr virus-positive carriers

The Epstein-Barr virus (EBV) is the causative agent of infectious mononucleosis and is implicated in the development of several human malignancies. Latent membrane protein 1 (LMP1), an EBV protein with known oncogenic properties, may be important in the pathogenesis of EBV-associated tumors, particularly nasopharyngeal carcinoma (NPC) and Hodgkin's disease (HD). Several reports suggested that sequence variations in the LMP1 gene may define a more aggressive, geographically restricted EBV-genotype. Most mutations in the LMP1 gene described are located within the C-terminus of the protein. However, the effect of these mutations on the biological function of the protein remains widely unknown. Therefore, this study aimed in investigating whether mutations detected in LMP1 genes isolated from different EBV-positive carriers have an effect on the biological function of the protein. For this purpose the LMP1 genes were amplified by nested PCR from DNA out of bone marrow and peripheral blood lymphocytes and sequenced. Three functional assays were performed in order to evaluate the biological activity of the different isolates: activation of the transcription factors NF-kappaB and AP-1 as well as the anchorage independent growth of LMP1 transfected ratl cells in soft agar. The results suggested that whereas differences in the activation of NF-kappaB through the various LMP1 isolates correlated tightly with their different expression levels, the outgrowth of transfected cells in soft agar did not and the transcription factor NF-kappaB therefore appeared not to be the major effector for the transformation of the rodent cell line ratl by LMP1. The various LMP1-isolates also differed in their capacity in activating the transcription factor AP-1. We found no correlation between the transforming ability of the LMPI isolates and activation of AP-1 suggesting that other so far uncharacterized domains also influence the transforming ability of the protein.

Kawasaki disease and human lymphotropic virus infection

Human lymphotropic viruses interacting with human immune systems may cause a wide spectrum of human diseases. Kawasaki disease has been thought to be related to events associated with infection, although a direct causative role has not been clearly demonstrated. In this concise review, the reported relationship between human lymphotropic viruses and Kawasaki disease is briefly described.

Comparative evaluation of the use of immunoblots and of IgG avidity assays as confirmatory tests for the diagnosis of acute EBV infections

BACKGROUND

Despite the availability of several different markers for Epstein--Barr virus (EBV) serology, the EBV status of some patients cannot be resolved from a single serum sample with routine testing. To avoid the requirement of follow-up samples, supplementary tests have to be used in these cases.

OBJECTIVE

To evaluate the usefulness of avidity and immunoblot assays as supplementary tests for the diagnosis of acute EBV infections.

STUDY DESIGN

Three groups of samples for which a definite diagnosis on the EBV status could not be obtained with the routine serological tests were further examined by an EBV IgG avidity assay, by an immunoblot based on a lysate of EBV infected cells, and by a second immunoblot based on recombinant EBV antigens. The three groups consisted of 38 samples with negative/borderline EB nuclear antigen 1 (EBNA-1) antibodies, negative/borderline EBV IgM and positive EBV IgG; 10 samples with indeterminate EBNA-1 and/or EBV IgM assays because of control antigen reactions; and 4 samples with positive EBV IgM results that were not plausible.

RESULTS

The avidity assay differentiated between acute and past infections for all samples. In contrast, some cases remained unresolved with both the recombinant and the lysate immunoblot. Two samples were incorrectly classified with the lysate immunoblot. Interpretation of the lysate immunoblot banding patterns was complicated when anticellular antibodies were present.

CONCLUSION

Avidity testing appears to be the confirmatory method of choice to differentiate between acute and past EBV infections.

The Epstein-Barr virus (EBV) major envelope glycoprotein gp350/220-specific antibody reactivities in the sera of patients with different EBV-associated diseases

gp350 of Epstein-Barr virus (EBV) induces a strong immune response in EBV-infected individuals, but relatively little is known about the clinical relevance of this response in patients with different EBV-associated malignancies and other diseases. Using our gp350-expressing cell clones, we studied gp350-specific humoral immune responses in the sera of individuals with nasopharyngeal carcinoma (NPC), chronic symptomatic EBV infection (CEI), Hodgkin's disease (HD), acute infectious mononucleosis (IM) and healthy EBV-seropositive individuals (HI). The titres of antibody-dependent cellular cytotoxicity (ADCC) antibodies were highest in HI followed by CEI, HD and NPC. EBV-neutralizing (NA) and gp350-specific IgG antibody profiles in these conditions were: CEI > HI > NPC > HD, whereas IgA titres were the highest in NPC sera followed by CEI and HD. The sera from IM patients were found to be negative for gp350-specific ADCC and IgA activities. Sera from HI were also negative for gp350-specific IgA. A significant positive correlation was found between serum gp350 IgA and viral capsid antigen IgA and a significant negative one between IgM and ADCC titres. High IgA titres were also found in CEI and EBV-genome positive HD in addition to NPC. Importantly, gp350-specific IgA titres were of prognostic value in NPC patients. Our data provide new insights about the clinical relevance of gp350-specific immune responses in these diseases.

Oncogens in ENT and head and neck - a review

With the exploration of new horizons in the frontiers of genetic linkage with head and neck cancer by advanced molecular biological technique it may be possible to know the various steps involved in the cancer development and new prognostic markers for not only predicting prognosis but also progression and predisposition including routine diagnostic tests for mutantgenes for a better diagnosis and treatment of squamous cell cancers of head and neck. Various oncogens and their products so far identified are ras, myc, c-erb, Bl, PRAD-.l, int-2, hst-1 and p 53 etc with lirikage to head and neck malignancy. The HLA gene association is the most convincing evidence for the role of genetics in the aetiology of nasopharyngeal cancer. EGFR looks to be a promising prognostic indicator as its interaction with the polypeptide epidermal growth factor stimulates proliferation of target cells.

PCR ELISA for the quantitative detection of Epstein-Barr virus genome

A highly sensitive and nonradioactive microplate hybridization assay for the detection of Epstein-Barr virus (EBV)-specific polymerase chain reaction (PCR) product was developed. The PCR product is labelled by adding digoxigenin-dUTP directly to the reaction mixture and, after denaturation, is captured by a microtitre plate coated with an extravidin-linked biotinylated probe. Captured products are reacted with a peroxidase-conjugated anti-digoxigenin antibody and detected using tetramethylbenzidine. The assay detected less than ten EBV genomes in a background EBV-negative DNA of 0.75 microg and, when tested on clinical samples, it was able to define the viral load in throat washings of patients with acute infectious mononucleosis, immunosuppressed patients with HIV infection, and rare normal individuals who shed the virus in the oropharynx.

Serodiagnosis of infectious mononucleosis in children

BACKGROUND

Although anti-viral capsid antigen (VCA)-immunoglobin M (IgM) is the most reliable serological marker of primary Epstein-Barr virus (EBV) infection, it could only be detected in limited cases of infectious mononucleosis in children. We analyzed anti-EBV antibodies by an enzyme-linked immunosorbent assay (ELISA), a sensitive method for detecting IgM antibody and compared these results with those obtained by a conventional indirect immunofluorescence (IF) method.

METHODS

Anti-Epstein-Barr virus early antigen (EA)-IgM and nuclear antigen 1 (EBNA1)-IgG were examined by an ELISA assay in 180 sera from 70 infants and children with infectious mononucleosis, diagnosed serologically by standard IF methods.

RESULTS

Although by IF, VCA-IgM was detected in only 37 of 70 (52.9%) of the sera from the acute phase of the disease, by ELISA, EA-IgM was detected in 65/70 (92.9%) of these sera. Among infants less than 12 months of age. EA-IgM was positive in 11/13 cases (84.6%) while VCA-IgM was detected in only 3/13 cases (23.1%). Anti-Epstein-Barr virus nuclear antigen 1-IgG was not detected by ELISA in the sera from the acute phase of infectious mononucleosis. Anti-EBNA was not detected by IF in about one-third of the sera during 6-8 months after onset of the disease, whereas by ELISA, EBNA1-IgG was detected in 93.0%. Sera that were positive or negative for both EA-IgM and EBNA1-IgG by ELISA were observed in several cases after the patients recovered from the disease.

CONCLUSIONS

Although serodiagnosis by the combination of ELISA for EA-IgM and EBNAI-IgG was more sensitive than IF methods, especially in the case of infants and young children, several patients during convalescence and recovery might be judged as seronegative or as being in highly reactivated states.

Epstein-Barr viral gene expression in B-lymphocytes

The strategy of the Epstein-Barr virus to persist lifelong in the host depends on establishing a reservoir, which cannot be detected by the immune system but allows reactivation of the virus for shedding and transmission to a new host. Epithelial cells and B-cells play a major role in this viral strategy of EBV, since differentiating epithelial tissues were shown to be permissive for lytic replication in vivo, whereas the B-lymphocytes become predominantly latently infected. However, which cells are the reservoir and which the sites of lytic replication are not quite clear. With the technique of reverse transcription, PCR and immunohistochemistry, we demonstrated that the B-cells of the peripheral blood are a major site of virus production during the primary infection during infectious mononucleosis. These permissive B-cells were also detected after convalescence, however, the absence of any lytic transcripts suggested an efficient immunological control very early in the viral lytic cycle. Serological data on reactivation of EBV correlated with the detection of lytic cycle transcripts in the blood and thus demonstrated that the site of virus production during infectious mononucleosis must be different from that of the persistent state. In those cases, where the infection takes a chronic active course, control of lytic replication is insufficient, either on the level of immune surveillance or of viral gene regulation. We have demonstrated a virus strain with a lytic phenotype in an individual suffering chronic active infection. The impaired capability of this virus to immortalise B-cells correlated with an enhanced expression of the lytic switch gene BZLF-1 and down-regulation of latent regulatory genes in the early phase of infection.

The use of semi-automated EBV IgG avidity determination for the diagnosis of infectious mononucleosis

The diagnosis of acute Epstein-Barr virus (EBV) infection is based frequently on the combination of positive viral capsid antigen (VCA) IgM antibodies and negative EB viral nuclear antigen 1 (EBNA-1) IgG antibodies. However, both VCA IgM and EBNA-1 IgG can provide false positive and false negative results. Therefore, situations in which the EBV serology remains unclear are not uncommon. Determination of EBV IgG avidity can clarify the EBV status in these patients. So far, mainly immunofluorescence assays have been used for this purpose. These tests are laborious, their evaluation is subjective, and automation is difficult. Therefore, two commercially available microtiter plate enzyme immunoassays (EIA) were compared for their usefulness for semi-automated EBV IgG avidity determination. One assay is based on a mixture of EBV antigens, the other assay uses a synthetic peptide of the VCA-complex. Patient sera of confirmed acute and past EBV infections were tested for avidity by both assays. The results with the antigen mixture assay proved to be highly sensitive (100%) and specific (100%). Avidity index calculations on the basis of one-point-quantification titers gave better results than calculations using OD values. Determination of EBV IgG avidity by the peptide assay was complicated by the fact that it was less sensitive than the antigen mixture assay for IgG detection in acute EBV infections. On the other hand, about 30% of the samples had to be retested with the peptide assay in a higher dilution because the IgG units in initial testing fell outside the range covered by the standard curve. Using OD values of the peptide EIA, the sensitivity was 99% but the specificity of detection of acute EBV infections was only 86%. Thus, while the peptide EBV avidity assay is unsuitable as a confirmatory assay, avidity testing with the antigen mixture assay is a useful tool to resolve equivocal EBV serologies. Avidity assays on the basis of EIA can be automated which should lead to wider use of this methodology.

Evaluation of three commercial enzyme-linked immunosorbent assays and two latex agglutination assays for diagnosis of primary Epstein-Barr virus infection

Three commercially available enzyme-linked immunosorbent assays (ELISAs) from Gull, Biotest, and Behring (Enzygnost) and two latex agglutination tests for heterophile antibodies (Monolatex [Biotest] and Mono-Lex [Trinity Laboratories]) were evaluated for the diagnosis of primary Epstein-Barr virus (EBV) infection and EBV seropositivity. Two hundred fourteen consecutive samples from 197 patients with symptoms of primary EBV infection were analyzed by the five assays at a clinical microbiology laboratory. The samples were also analyzed independently by immunofluorescence methods at a reference laboratory. According to the reference methods, 37 patients (40 serum samples) had primary EBV infections, 120 patients (127 serum samples) had had past EBV infections, 33 patients (36 serum samples) were seronegative, and 7 patients (11 serum samples) exhibited atypical reactions. The respective sensitivities and specificities for the diagnosis of primary EBV infection were 95 and 100% for the Gull assays, 100 and 94% for the Biotest assays, and 100 and 89%, for the Enzygnost assays. The Monolatex and Mono-Lex methods showed similar sensitivities and specificities (78 to 85% and 100 to 99%, respectively) for the diagnosis of primary EBV infection. This study demonstrates the usefulness of commercially available assays for the rapid diagnosis of primary EBV infection, but also the importance of large-scale testing of routine samples before choosing an assay.

Specific diagnostic methods for herpesvirus infections of the central nervous system: a consensus review by the European Union Concerted Action on Virus Meningitis and Encephalitis

BACKGROUND

Herpesvirus infections of the central nervous system are often severe but are fortunately rare. The incidence of these infections has however, increased in recent years as a consequence of an increase in the number of immune-compromised individuals. New diagnostic procedures have improved our ability to diagnose these infections and herpesviruses may yet be implicated as the cause of further neurological diseases with no known aetiology. Methodological standards for selection and evaluation of patient materials are essential to the provision of reliable diagnosis, yet few studies have addressed this important issue.

OBJECTIVES

To describe and define methodological standards and reference methodology for diagnosis of herpesvirus infections of the CNS.

STUDY DESIGN

Information gathered by literature review.

RESULTS

Only for herpes simplex encephalitis is there sufficient data to allow the definition of reference methodology. Good methodological standards exist but few studies have adhered to these standards. As methods for the detection of specific intrathecal antibody synthesis are well established yet under-used in diagnostic virology, the principle of these measurements is reviewed in some detail.

CONCLUSIONS

Herpesvirus infections of the CNS are of increasing importance. High quality, multi-centre studies are needed to establish the value of the new diagnostic test procedures if further improvement in the diagnostic sensitivity and specificity of these procedures is to be achieved.

Lymphoepithelioma-like carcinoma of the uterine cervix: association with Epstein-Barr virus and human papillomavirus

BACKGROUND

The presence of Epstein-Barr virus (EBV) has not been documented in previous reports of lymphoepithelioma-like carcinoma (LELC) of the uterine cervix by either polymerase chain reaction or in situ hybridization, and the histogenesis of the tumor remains unknown. Additionally, a relationship between human papillomavirus (HPV) and cervical LELC also has not been reported.

METHODS

In this article, the authors describe the clinical and histopathologic findings for 15 patients with cervical carcinoma that had a histologic pattern of LELC. The polymerase chain reaction detected the presence of EBV and HPV DNA sequences in cervical LELC.

RESULTS

All 15 tumors showed a typical syncytial growth pattern of undifferentiated cells with prominent lymphocytic infiltration. The detection rate of the EBV gene sequence in tissue samples from patients with LELC was more frequent than that in control patients with squamous cell carcinoma of the cervix (11 of 15 patients, 73.3%, vs. 4 of 15 patients, 26.7%; P = 0.01). However, the detection rate of HPV-16 and HPV-18 DNA was significantly lower in patients with LELC tumors than in patients with cervical squamous cell carcinoma (3 of 15 patients, 20.0%, vs. 12 of 15 patients, 80.0%; P = 0.001). After a median follow-up of 3.9 years (range, 1.8-5.3 years), the 15 patients showed no evidence of disease or metastasis after radical hysterectomy or radiotherapy.

CONCLUSIONS

The finding of EBV associations in cervical LELC supports the hypothesis that EBV may be involved in the pathogenesis of tumors that arise in the cervix. It is possible that cervical LELC may follow a different pathway in the pathogenesis of LELC in Asian women as compared with the more common forms of squamous cell carcinoma.

Antarctic isolation: immune and viral studies

Stressful environmental conditions are a major determinant of immune reactivity. This effect is pronounced in Australian National Antarctic Research Expedition populations exposed to prolonged periods of isolation in the Antarctic. Alterations of T cell function, including depression of cutaneous delayed-type hypersensitivity responses and a peak 48.9% reduction of T cell proliferation to the mitogen phytohaemagglutinin, were documented during a 9-month period of isolation. T cell dysfunction was mediated by changes within the peripheral blood mononuclear cell compartment, including a paradoxical atypical monocytosis associated with altered production of inflammatory cytokines. There was a striking reduction in the production by peripheral blood mononuclear cells of the predominant pro-inflammatory monokine TNF-alpha and changes were also detected in the production of IL-1, IL-2, IL-6, IL-1ra and IL-10. Prolonged Antarctic isolation is also associated with altered latent herpesvirus homeostasis, including increased herpesvirus shedding and expansion of the polyclonal latent Epstein-Barr virus-infected B cell population. These findings have important long-term health implications.

High susceptibility of an Epstein-Barr virus-converted Burkitt's lymphoma cell line to cytotoxic drugs

Susceptibility to cytotoxic drugs was studied using an Epstein-Barr virus (EBV) genome-negative Burkitt's lymphoma (BL) cell line (Ramos) originating from the tumor cells and an in vitro EBV-converted Ramos cell line (B7). Decreased doubling time (DT) with increased saturation density (SD) and elevated [3H]thymidine incorporation were shown in B7, indicating more rapid cell proliferation and growth. However, B7 was highly susceptible to cytotoxic drugs when compared to Ramos. These results indicated whether the presence or absence of EBV genome in tumor cells may be beneficial for evaluation of susceptibility to cytotoxic chemotherapy in patients with BL.

Epstein-Barr virus-associated dural leiomyosarcoma in a man infected with human immunodeficiency virus. Case report

A 35-year-old man infected with human immunodeficiency virus presented with cervical myelopathy of 2 months duration. Clinical and radiographic evaluation revealed a discrete, subdural mass at C-6. At surgery, the mass proved to have a dural attachment and thus clinically, radiographically, and grossly, it resembled meningioma. Histopathological analysis revealed a leiomyosarcoma that stained diffusely for muscle-specific actin. Electron microscopy revealed basal lamina surrounding the tumor cells and intracytoplasmic bundles of myofilaments. Epstein-Barr virus (EBV) was demonstrated within tumor cell nuclei by in situ hybridization for EBER1 messenger RNA and immunohistochemical staining for EBNA2 protein. Epstein-Barr virus latent membrane protein (LMP1) was not detected. This is the first documentation of an EBV-associated smooth-muscle tumor of the dura, and the first demonstration that tumors in this location contain EBV in an unusual form of latency not seen in lymphoid cell lines. With increasing numbers of individuals being afflicted with long-term immunosuppression, EBV-associated dural leiomyoma and leiomyosarcoma may be encountered more frequently in the future.

Lytic Replication of Epstein-Barr Virus in the Peripheral Blood: Analysis of Viral Gene Expression in B Lymphocytes During Infectious Mononucleosis and in the Normal Carrier State

Epstein-Barr virus (EBV) has been shown to establish latency in resting B lymphocytes of the peripheral blood. This creates a virus reservoir in contrast to lytic virus replication, which is thought to be restricted to differentiated epithelial cells in vivo. So far, the route of transmission between B cells and the production of progeny virus in the epithelial tissue has remained unclear. Reverse transcriptase–polymerase chain reaction (RT-PCR) and immunohistochemistry analysis of 16 patients with acute infectious mononucleosis (IM) and 25 healthy seropositive donors was performed to detect lytic replication gene products in B lymphocytes of the peripheral blood. Transcriptional activity was found in peripheral blood B lymphocytes (PBLs) for BZLF1 in 88%, BALF2 in 50%, and BcLF1 in 25% of the tested IM patients. All positive results were further confirmed in enriched B-cell populations by antigen determination using immunostaining with the APAAP technique. Furthermore, we detected transcripts for BZLF1 in 72% and for BALF2 in 16% of peripheral B lymphocytes of healthy seropositive donors. In contrast to patients with IM, no signals for BcLF1 were ever found in healthy seropositive donors. In these individuals, lytic replication of EBV is probably restricted by immunologic and gene regulatory mechanisms, whereas in the absence of immunologic control, reflected here by IM patients, the production of infectious virus becomes visible in PBLs.

Lytic Replication of Epstein-Barr Virus in the Peripheral Blood: Analysis of Viral Gene Expression in B Lymphocytes During Infectious Mononucleosis and in the Normal Carrier State

Epstein-Barr virus (EBV) has been shown to establish latency in resting B lymphocytes of the peripheral blood. This creates a virus reservoir in contrast to lytic virus replication, which is thought to be restricted to differentiated epithelial cells in vivo. So far, the route of transmission between B cells and the production of progeny virus in the epithelial tissue has remained unclear. Reverse transcriptase–polymerase chain reaction (RT-PCR) and immunohistochemistry analysis of 16 patients with acute infectious mononucleosis (IM) and 25 healthy seropositive donors was performed to detect lytic replication gene products in B lymphocytes of the peripheral blood. Transcriptional activity was found in peripheral blood B lymphocytes (PBLs) for BZLF1 in 88%, BALF2 in 50%, and BcLF1 in 25% of the tested IM patients. All positive results were further confirmed in enriched B-cell populations by antigen determination using immunostaining with the APAAP technique. Furthermore, we detected transcripts for BZLF1 in 72% and for BALF2 in 16% of peripheral B lymphocytes of healthy seropositive donors. In contrast to patients with IM, no signals for BcLF1 were ever found in healthy seropositive donors. In these individuals, lytic replication of EBV is probably restricted by immunologic and gene regulatory mechanisms, whereas in the absence of immunologic control, reflected here by IM patients, the production of infectious virus becomes visible in PBLs.

Therapeutic approaches for severe Epstein-Barr virus infection

Epstein-Barr virus, (EBV) is one of the eight known human herpesviruses and is associated with diseases in a spectrum from benign to lethal. Until recently, there has been no definite treatment for severe EBV infection. However, many therapeutic approaches have been attempted, and some of them seem to be beneficial for a certain EBV-associated disease. This review introduces them and provides a more rational basis for the treatment of severe EBV infection.

Post-transplant EBV induced lymphoproliferative disorders

Epstein Barr virus induced lymphoproliferative disease (EBV-LPD) is a heterogeneous disorder, ranging from polyclonal lymphoproliferations to malignant lymphoma, typically seen in individuals with inadequate cellular immunity to EBV. The diagnosis of EBV-LPD following transplant requires a high index of suspicion in those patients at risk. Unlike organ transplant patients, in whom lymphomas are generally of host origin and respond to decreases in immunosuppression, bone marrow transplant recipients have donor origin tumors that are not as responsive to conservative treatment modalities. For the latter group, adoptive immunotherapy with donor lymphocytes is the treatment of choice and generally results in complete eradication of these tumors. Whether adoptive immunotherapy can be used for EBV-LPD in patients following organ transplantation is currently being investigated.

Epstein-Barr virus-associated hemophagocytic syndrome and fatal infectious mononucleosis

Virus-associated hemophagocytic syndrome (VAHS) has been thought to be a distinct clinical entity, characterized by intermittent fever, enlarged liver and spleen, and the appearance of hemophagocytosis. Hemopoietic cells are actively ingested by monocytes/macrophages in various organs, including lymph nodes, bone marrow, liver, and spleen. Epstein-Barr virus (EBV) is now thought to be one of the major causes for the development of this unique syndrome. Additionally, VAHS is often associated with fatal infectious mononucleosis (IM). The relationship between EBV-associated VAHS and fatal IM is discussed in this concise review.

Epstein-Barr virus in tumours

The Epstein-Barr virus (EBV) is the best characterized human virus known to infect most people all over the world. In most cases, primary infection with EBV is asymptomatic and the virus persists life-long without causing any disease. The availability of sensitive detection methods, however has led to the identification of a wide array of EBV-associated disease entities. Although nearly 9000 publications have been written since the first description of this virus in 1964, many questions concerning its function and infection patterns remain unanswered. The direct involvement of EBV in the pathogenesis of a disease has only been established for infectious mononucleosis and lymphoproliferative disorders in the setting of congenital or acquired immunodeficiency. Extensive investigations on the role of EBV infection in the pathogenesis of all other EBV-associated lymphoid and epithelial proliferations have led to the conclusion that EBV is not the primary causative agent but it can promote tumour development. Since the early steps in neoplastic development are difficult to assess, further studies are required to clarify the precise role of EBV infection. Furthermore, the clinical significance of the presence of EBV in neoplasia is largely unknown.

Direct detection of Epstein-Barr viral antigen in nasopharyngeal swabs from patients with infectious mononucleosis

OBJECTIVE

To determine whether direct immunologic detection of Epstein-Barr virus (EBV) early antigen diffuse component (EA-D) from nasopharyngeal swabs is a feasible approach to the development of a rapid diagnostic test for infectious mononucleosis (IM).

METHODS

Nasopharyngeal swabs from 20 patients presenting with a presumptive diagnosis of IM (having the classic triad of symptoms-acute pharyngitis, fever, and lymphadenopathy) and 5 controls were assayed for EA-D. EBV serologic testing and a heterophil antibody titer (HAT) test also were performed. EA-D was assayed by polyacrylamide gel electrophoresis and subsequent transfer to a nylon membrane, followed by immunoblotting with a monoclonal antibody.

RESULTS

EA-D was detected in 17 of 20 patients (85%) with presumptive diagnoses of IM and in 1 of 5 normal subjects and was highly significant in predicting IM (p < 0.01). There was no significant difference in numbers of positive and negative results using either EA-D assay or HAT test in patients with IM (p < 0.35). Pharyngeal exudate in the 17 pharyngitis patients with this variable documented was significantly correlated with positive EA-D (p < 0.01), but not with the HAT test (p < 1.00).

CONCLUSIONS

Immunologic detection of EBV-derived antigens from nasopharyngeal swabs is a potential early diagnostic tool for clinically suspected IM. Sensitivity and specificity in pediatric and adult populations, patients with other viral etiologies, and patients with streptoccocal pharyngitis should be determined in subsequent investigations.

Detection of an Epstein-Barr-virus variant in T-cell-lymphoma tissues identical to the distinct strain observed in nasopharyngeal carcinoma in the Taiwanese population

An EBV variant has been identified in NPC tissues in Taiwan. This EBV variant contains a point mutation in exon I of the LMP I gene. This mutation results in the loss of an XhoI site at nt 169,426, which is present in strain B95-8. In addition, this variant contains a 30-bp deletion in exon 3 of the gene. The recent demonstration of the prevalence of EBV-containing nasal and peripheral T-cell lymphoma in this region drove us to evaluate the presence of this NPC-EBV strain in 7 cases of T-cell lymphoma, as well as in 48 NPC tissues, 2 cases of Hodgkin's disease and I B-cell lymphoma. Four samples of normal lymph node tissue, 40 of normal nasopharynx tissue and 78 throat washings of healthy individuals were included for comparison. We used sequence-specific primers and the polymerase chain reaction (PCR) method to amplify LMP I gene fragments containing these variations. Mutations were then confirmed by restriction-enzyme digestion and the DNA sequencing analysis. Our results showed that 57 of 58 tumor-tissues samples were EBV-positive. Among them, 56, including 6 T-cell-lymphoma samples, belonged to the NPC strain. This strain of EBV was also present in 92% of EBV-positive normal nasopharynx tissues and in 84% of EBV-positive throat washings of the healthy individuals tested. These results suggest that the NPC-EBV strain is prominently present in Taiwan.

The presence of Epstein-Barr virus in multiple organs in a fatal case of virus-associated haemophagocytic syndrome

We describe a case report of a 21-year-old male with fatal Epstein-Barr virus-associated haemophagocytic syndrome. Virus is detected in multiple organs by polymerase chain reaction and in the tissue-specific cells of those organs by in situ hybridisation. It is suggested that organ failure may be a direct response to infection.

Simple assay for evaluation of Epstein-Barr virus specific cytotoxic T lymphocytes

Epstein-Barr virus (EBV)-specific cytotoxic T lymphocytes (CTL) are considered to be one of major defenses against the activation of EBV infection. We have developed a simple assay for evaluation of EBV-CTL by means of culturing peripheral blood mononuclear cells at the concentration of 2 x 10(6) cells/ml infected by B95-8 EBV, in the presence or absence of cyclosporin A (CSA). No lymphoblastoid cell line was established from ten EBV-seropositive healthy individuals in the absence of CSA. In contrast, cell lines were established from ten EBV-seronegative healthy individuals in the absence of CSA, indicating lack of EBV-CTL in these individuals. Methods described herein are simple and correlate well with EBV-CTL activity when compared to conventional methods, such as outgrowth regression or chromium-51 release assays.

Epstein-Barr virus (EBV) hypersensitivity of peripheral B lymphocytes in patients with EBV genome-positive Burkitt's lymphoma

Peripheral blood mononuclear cells (PBMC) from four Japanese patients with Epstein-Barr virus (EBV) genome-positive Burkitt's lymphoma (BL) during remission were exposed to the B95-8 strain of EBV. Maximum concentrations of the EBV-determined nuclear antigen (EBNA) before cellular DNA synthesis were similar to those of healthy counterparts. Subsequently, EBV-immortalised cell lines were established. These immortalised lymphoblastoid cells were treated with 12-O-tetradecanoylphorbol-13-acetate (TPA) and superinfected with the P3HR-1 strain of EBV. EBV early antigens (EA) and viral capsid antigen (VCA) were expressed in approximately 3-10 fold higher concentrations by these lymphoblastoid cells than by those from patients with other types of malignant neoplasia including EBV genome-negative BL and from healthy counterparts. Moderate to extremely high IgG antibody titres to EBV VCA as well as IgG antibodies to EA were demonstrated in these patients during the study. These results suggest that defective underlying cellular mechanisms for regulating the replication of EBV may be present in patients with EBV genome-positive BL.

Peripheral blood lymphocyte subpopulations in three infants with hepatosplenomegaly caused by cytomegalovirus infection

Mononucleosis is defined as atypical lymphocyte proliferation which causes clinical symptoms such as tonsillitis, lymphadenopathy, or hepatosplenomegaly. Mononucleosis syndrome is caused by cytomegalovirus (CMV), Toxoplasma, hepatitis virus, adenovirus, or other agents as well as by Epstein-Barr virus. The syndrome is immunologically characterized by the proliferation of activated T cells (HLA-DR+ T cells). We encountered three infants with hepatosplenomegaly who were diagnosed as primary CMV infection by the detection of anti-CMV IgM antibody. Although the patients were otherwise asymptomatic, analysis of lymphocyte subpopulations showed a decreased ratio of CD4+ to CD8+ T cells and augmented expression of HLA-DR antigen on T cells characteristic of infectious mononucleosis. We conclude that inapparent CMV disease may affect the immunologic status of infected children even if it is asymptomatic.

Avidity of EBV VCA-specific IgG antibodies: distinction between recent primary infection, past infection and reactivation

A commercial Epstein-Barr virus (EBV) antivirus capsid antigen (VCA) IgG antibody ELISA and an 'in-house' EBV VCA IgG immunofluorescence antibody assay (IFA) were used to detect EBV VCA IgG antibodies in 100 serum samples collected from organ transplant recipients and immunocompetent individuals. The avidity of EBV VCA IgG antibodies was determined in the IFA and ELISA using the mild reducing agent 8 M urea to remove low avidity antibodies. The samples were collected from patients who had previously been identified with a primary EBV infection, a reactivation of latent infection or evidence of a past EBV infection by means of EBV-specific serology. Using the ELISA, the antibody avidity was low in samples collected from patients with recent EBV infection and high in samples collected from patients with a past infection or a reactivation. There was a statistically significant difference of means (P < 0.001) of percentage reduction in optical density values, measured in the presence of 8 M urea, obtained with samples collected from patients with recent infection compared with samples from patients with a past infection or a reactivation of latent infection.

Epstein-Barr virus as an agent of haematological disease

Epstein-Barr virus (EBV) encodes genes that permit its persistence in human B lymphocytes and genes that ensure its replication in epithelial cells. Immune restraints on the virus are usually so effective that most EBV infections are limited to a minute fraction of B lymphocytes and of epithelial cells. As a result, most EBV infections are never symptomatic. Occasionally, the virus causes disease, often with the cooperation of the immune system or other less characterized cofactors. Infectious mononucleosis, a generally self-limited lymphoproliferative illness common in adolescents and young adults, is due to primary EBV infection and to the brisk cellular immune response it elicits. Lymphoproliferative disorders of EBV-infected B cells arise almost exclusively when cellular immunity is grossly compromised. EBV-positive Burkitt's lymphoma contain a translocated and deregulated c-myc oncogene and EBV-positive non-Hodgkin's lymphomas are characterized by the presence of Reed-Sternberg's and Hodgkin's cells, features that have not been directly linked to EBV. Many recent observations, however, including evidence that virus infection precedes malignant transformation and is often associated with a characteristic pattern of viral gene expression, provide continued interest in the relationship between the virus and these haematological malignancies.

Epstein-Barr virus latent messages with shuffled leader exons: remnants of circumgenomic transcription?

The EBNA transcription unit which is active in Epstein-Barr virus-immortalized latently infected B lymphocytes covers approximately 60% of the 172-kb genome. Since the genome exists as a circular double-stranded DNA molecule in latently infected cells, it is conceivable that complete copies are made during transcription. Rather than attempt to detect gigantic RNA molecules directly, we used RNA-PCR to detect incorporation of leader exons into mRNA in a shuffled order. The downstream U leader exon was detected spliced upstream of the internal repeat leader exons W1 and W2 in the polyadenylated RNA fraction of spontaneous lymphoblastoid cell lines, restricted phenotype BL cell lines Wanyanyi and Wewak2, and in B95-8, Raji, and Akata cells. Quantitative competitive RNA-PCR showed that the ratio of U exon-containing EBNA1 messages to U exon-shuffled leader messages was approximately 10:1, with large variation from cell line to cell line, and was not affected by induction of the lytic cycle in B95-8, Raji, or Akata cells. Messages with shuffled exons contained only the C2W1 alternative splice, which does not produce an initiator AUG methionine codon for EBNA4 gene expression. The results provide evidence for long-range exon skipping and imply that genome-length transcripts may occur and participate in viral gene expression in latency.

Decreased cytoplasmic immunoglobulin A production during Epstein-Barr virus immortalization on lymphocytes from patients with ataxia-telangiectasia

Previously, we have reported significantly lower immunoglobulin (Ig) A production in supernatants of cultured lymphoblastoid cells using enzyme-linked immunosorbent assay from patients with ataxia-telangiectasia (AT) when compared to that of age- and sex-matched healthy individuals. Here, we further assess the degree of cytoplasmic Ig production in these cells and also analyze it during the early phase of Epstein-Barr virus immortalization. All classes of cytoplasmic IgM, IgG, and IgA productions were demonstrated in cells from healthy controls. In contrast, cells from patients with AT showed only cytoplasmic IgM and IgG with low or nondetectable levels of IgA during and after the immortalizing process. These results suggest B lymphocytes bearing IgA are functionally immature and/or defective in patients with AT.

Acute thrombocytopenic purpura associated with primary Epstein-Barr virus infection

Acute idiopathic thrombocytopenic purpura (ITP) often appears to be related to the sensitization by some viral infections. However, the causative viral agents are not identified in most cases. Although the primary infection with Epstein-Barr virus (EBV) occurs during early childhood in Japan, the majority of cases are usually asymptomatic. A minority are associated with acute infectious mononucleosis (IM), which is characterized by fever, tonsillitis, lymphadenopathy, splenomegaly and liver dysfunction. In this report, three cases are described of children with EBV-induced ITP who clinically had atypical findings of IM. Their primary EBV infections were confirmed by serological test and, in addition, were verified by the enhanced expression of activation antigens (HLA-DR and CD45RO) on T cells as well as the inverted ratio of CD4+ to CD8+ subsets. These observations imply that ITP can occur as one of the host responses during primary EBV infections, irrespective of clinical manifestations. Evaluation of lymphocyte subpopulations may be useful for the assessment of primary EBV infection in ITP.

Clinical characteristics of post-transplant lymphoproliferative disorders

PURPOSE

To study the histopathologic findings, clinical course, and therapeutic outcome of patients who developed a lymphoproliferative disorder after undergoing solid organ transplantation.

PATIENTS AND METHODS

A series of 26 patients who developed a lymphoproliferative disorder after solid organ transplant during a 27-year period were studied.

RESULTS

The 26 patients ranged in age from 6 to 68 years (median 42 years). The lymphoproliferative disorder was diagnosed from 1 to 211 months (median 80 months) after transplantation. The type of transplant was kidney (n = 21), heart or heart-lung (n = 4), or liver (n = 1). Most patients received azathioprine and prednisone, in addition to antilymphocyte globulin or cyclosporine, for post-transplant immunosuppression. Eight patients had lymphoma that could be classified according to the International Working Formulation (IWF-F, IWF-G, IWF-H). Sixteen patients had polymorphic lymphoma, and 2 patients were classified as having polymorphic lymphoid hyperplasia. Patients were staged by the Ann Arbor staging system. Nine patients had stage I disease, 4 stage II, 6 stage III, and 7 stage IV. Central nervous system, lung, or marrow involvement was present in 27%, 23%, and 14% of patients, respectively. In the 17 patients studied, immunophenotype was monoclonal B-cell (n = 12), malignant T-cell (n = 2), or polyclonal B-cell (n = 3). The initial therapeutic approach was generally a reduction in immunosuppression, but, thereafter, the approach to therapy varied. In patients with localized disease, surgical excision and/or involved field radiotherapy were utilized as applicable. For patients with more extensive disease, other approaches such as high-dose acyclovir, combination chemotherapy, or alpha interferon were utilized. Overall, 15 of 26 patients (58%) responded to systemic therapy or were rendered disease-free either by surgery or radiation, including 8 (31%) with a complete remission (CR). Only 3 of 9 patients responded to chemotherapy, whereas 4 of 13 patients responded to acyclovir (including 3 patients who experienced CR). Remission duration ranged from 8 to 122 months (median 32+ months). Twenty-one of 26 patients (81%) have died. Survival ranged from less than 1 to 122 months (median 14 months).

CONCLUSION

The outcome of patients with post-solid organ transplant lymphoproliferative disorders is poor, and the optimal approach to therapy is not clear. Newer therapeutic approaches are thus needed to improve the outcome of these patients.