Antibody response against the Epstein-Barr virus-coded nuclear antigen2 (EBNA2) in different groups of individuals

Antibody titers against EBNA1 and EBNA2 in relation to Hodgkin lymphoma and history of infectious mononucleosis

A role for Epstein Barr virus (EBV) in Hodgkin lymphoma (HL) pathogenesis is supported by the detection of EBV genome in about one-third of HL cases, but is not well defined. We previously reported that an elevated prediagnosis antibody titer against EBV nuclear antigens (EBNA) was the strongest serologic predictor of subsequent HL. For the present analysis, we measured antibody levels against EBNA components EBNA1 and EBNA2 and computed their titer ratio (anti-EBNA1:2) in serum samples from HL cases and healthy siblings. We undertook this analysis to examine whether titer patterns atypical of well-resolved EBV infection, such as an anti-EBNA1:2 ratio ≤ 1.0, simply reflect history of infectious mononucleosis (IM), an HL risk factor, or independently predict HL risk. Participants were selected from a previous population-based case-control study according to their history of IM. We identified 55 EBV-seropositive persons with a history of IM (IM+; 33 HL cases, 22 siblings) and frequency-matched a comparison series of 173 IM history-negative, EBV-seropositive subjects on HL status, gender, age and year of blood draw (IM-; 105 cases, 58 siblings). In multivariate logistic regression models, an anti-EBNA1:2 ratio ≤ 1.0 was significantly more prevalent in HL cases than siblings (odds ratio, 95% confidence interval = 2.43, 1.05-5.65); similar associations were apparent within the IM+ and IM- groups. EBNA antibodies were not significantly associated with IM history in HL cases or siblings. These associations suggest that chronic or more severe EBV infection is a risk factor for HL, independent of IM history.

Epstein-Barr virus and rheumatoid arthritis: is there a link?

Rheumatoid arthritis is a systemic autoimmune disease characterized by chronic, destructive, debilitating arthritis. Its etiology is unknown; it is presumed that environmental factors trigger development in the genetically predisposed. Epstein–Barr virus, a nearly ubiquitous virus in the human population, has generated great interest as a potential trigger. This virus stimulates polyclonal lymphocyte expansion and persists within B lymphocytes for the host's life, inhibited from reactivating by the immune response. In latent and replicating forms, it has immunomodulating actions that could play a role in the development of this autoimmune disease. The evidence linking Epstein–Barr virus and rheumatoid arthritis is reviewed.

Elevated immunoglobulin G antibodies to the proline-rich amino-terminal region of Epstein-Barr virus nuclear antigen-2 in sera from patients with systemic connective tissue diseases and from a subgroup of Sjögren's syndrome patients with pulmonary involvements

Associations of Epstein-Barr virus (EBV) and autoimmune diseases have been hypothesized. We have analysed IgG antibodies to EBV nuclear antigen (EBNA)-2 in sera from Japanese patients with autoimmune systemic connective tissue diseases (CTD), exemplified by systemic lupus erythematosus (SLE), primary Sjogren's syndrome (SS), rheumatoid arthritis (RA), systemic sclerosis (SSc) and secondary SS (classical CTDs complicated with SS). An enzyme-linked immunosorbent assay (ELISA) which uses glutathione-S-transferase polypeptides fused to EBV nuclear antigen (EBNA)-2 and EBNA-1 was developed. Ratios of IgG antibody reactivity to whole IgG concentrations of sera were calculated to normalize EBNA-2 and EBNA-1 antibody levels to the hypergammaglobulinaemia that occurs in CTD. The ELISA optical density OD(450) readings of IgG antibodies to both the amino-terminal aa 1-116 of EBNA-2 and carboxyl-terminal aa 451-641 of EBNA-1 were elevated significantly in patients with SLE, primary SS, RA, SSc and secondary SS when compared to EBNA-1. The OD readings were divided by serum IgG concentrations to normalize for the hypergammaglobulinaemia. The specific levels of IgG antibodies to the amino-terminal region of EBNA-2 were elevated in patients with SLE, primary SS or RA, as well as those with secondary SS complicated with SLE or RA. The EBNA-2 amino-terminal region contains a polyproline tract and a proline-rich sequence and has considerable amino acid sequence homology with many cellular proline-rich proteins. High ratios of EBNA-2 aa 1-116 to EBNA-1 aa 451-641 IgG antibody levels which probably suggest reactivation of EBV latent infection were associated significantly with pulmonary involvement in SS patients. These results are consistent with the hypothesis that the sequence similarity between the amino-terminal region of EBNA-2 and proline-rich cellular proteins is associated with pathogenesis in a subpopulation of CTD patients, possibly by the molecular mimicry-epitope shift mechanism.

Immune responses to Epstein-Barr virus lytic proteins in patients with nasopharyngeal carcinoma

Immune responses to three Epstein-Barr virus (EBV) lytic proteins, DNase, thymidine kinase (TK), and BMRF-1 gene products (50/52 kDa diffused early antigen, EA-D complex) were determined in EBV-infected control individuals and patients with nasopharyngeal carcinoma (NPC). Immunofluorescence assays (IFA) were used to detect their humoral immune responses using recombinant EBV lytic proteins expressed in a baculovirus system as antigens. Cell proliferation assays were performed to evaluate their cellular immune responses by monitoring 3H-thymidine incorporation. Seventy patients with NPC and 32 non-cancer controls were analyzed. The results of IFA showed antibody titers to all three EBV lytic proteins to be higher in the patients with NPC especially for the IgA class. Positivity rates of the three IgA antibodies also were higher in the patients with NPC population. Furthermore, the profiles of the IgA antibodies correlated with those to total early antigens (EA) expressed in the early phase and viral capsid antigen (VCA) expressed in the late phase, of EBV replication. The most interesting finding was that antibody titers to the three EBV lytic proteins were associated significantly with metastases of cervical lymph nodes in patients with NPC. As for cellular immunity to the EA-D complex and DNase, weak responses were observed in the cell proliferation assays. Peripheral blood cells from most individuals could not be stimulated to proliferate, except for a few patients with NPC whose antibody titers against the EA-D complex and DNase also were very high.

Maintenance of serum immunoglobulin G antibodies to Epstein-Barr virus (EBV) nuclear antigen 2 in healthy individuals from different age groups in a Japanese population with a high childhood incidence of asymptomatic primary EBV infection

Immunoglobulin G (IgG) antibodies to Epstein-Barr virus (EBV) nuclear antigens 2 and 1 (EBNA-2 and EBNA-1, respectively) were studied using sera from healthy individuals of a population with a high incidence of asymptomatic primary EBV infections during infancy or childhood in Japan. Two CHO-K1 cell lines expressing EBNA-2 and EBNA-1 were used for anticomplement and indirect immunofluorescence assays. The positivity rate for EBNA-2 IgG rose in the 1- to 2-year age group, increased and remained at a plateau ( approximately 45%) between 3 and 29 years of age (3- to 4-, 5- to 9-, 10- to 14-, and 15- to 29-year age groups), and then reached 98% by age 40 (>/== 40-year age group). Both seropositivity for EBNA-1 and seropositivity for EBNAs in Raji cells (EBNA/Raji) were detected in the 1- to 2-year age group, remained high, and finally reached 100% by age 40. The geometric mean titer (GMT) of EBNA-2 IgG reached a plateau in the 5- to 9- and 10- to 14-year-old groups and remained elevated in the older age groups (15 to 29 and >/== 40 years). The GMT of EBNA-1 IgGs increased to a plateau in the 1- to 2-year-old group and remained unchanged in the older age groups. The GMT of EBNA/Raji IgGs also reached a plateau in the 1- to 2-year-old group, remained level throughout the 3- to 14-year age groups, and decreased in the 15- to 29-year-olds. EBNA-2 IgGs emerged earlier than EBNA-1 IgGs in 8 of 10 patients with infectious mononucleosis, who were between 1 and 27 years old, and declined with time in three of eight cases. These results suggest that EBNA-2 IgG antibodies evoked in young children by asymptomatic primary EBV infections remain elevated throughout life, probably because of reactivation of latent and/or exogenous EBV superinfection.

Evaluation of an Epstein-Barr virus (EBV) immunoglobulin M enzyme-linked immunosorbent assay using a synthetic convergent peptide library, or mixotope, for diagnosis of primary EBV infection

An immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) was developed by using a 24-amino-acid peptide of the 18-kDa Epstein-Barr virus (EBV) viral capsid antigen (VCAp18). IgM detection was increased by 23% by using this antigen. Detection of IgM antibodies to the EBV proteins in the new ELISA was 100% specific and 95% sensitive.

Hodgkin disease occurring in a patient with extremely high serum antibody titers to Epstein-Barr virus--associated antigens without chronic illness

PURPOSE

We described for the first time a patient with long-lasting, extremely high serum antibody titer against Epstein-Barr virus (EBV) viral capsid antigen and early antigen without clinical symptoms suggestive of active EBV infection; the patient finally developed Hodgkin disease (HD) after 7 years of follow-up.

PATIENT AND METHODS

High serum EBV antibody titers were noted at 2 years of age. Immunological evaluation was performed at the age of 7 years. EBV-specific cytotoxic T-lymphocyte activity was normal. None of the other results showed any significant abnormalities except for the abnormal antibody titers against EBV-associated antigens.

RESULTS

The patient developed HD at the age of 9 years. In addition, EBV genomes were found in the nuclei of Hodgkin and Reed-Sternberg cells in the lymph node.

CONCLUSIONS

This case suggests that (a) a patient with extremely high serum antibody titers against EBV-associated antigens may develop HD after a prolonged period, even though no clinical symptom suggestive of active EBV infection is observed; (b) EBV may play an important role in the occurrence of HD.

Seroconversion to antibodies against Kaposi's sarcoma-associated herpesvirus-related latent nuclear antigens before the development of Kaposi's sarcoma

BACKGROUND

If Kaposi's sarcoma-associated herpesvirus (KSHV) is the cause of Kaposi's sarcoma, serologic evidence of infection should be present in patients before the disease develops.

METHODS

Using an immunoblot assay for two latent nuclear antigens of KSHV, we tested serum samples from homosexual male patients with the acquired immunodeficiency syndrome (AIDS) with and without Kaposi's sarcoma (HIV-infected men with hemophilia), HIV-seronegative blood donors, and HIV-seronegative patients with high titers of antibodies against Epstein-Barr virus (EBV). Serial serum samples obtained from patients with Kaposi's sarcoma before the diagnosis of the disease were tested for evidence of seroconversion.

RESULTS

Of 40 patients with Kaposi's sarcoma, 32 (80 percent) were positive for antibodies against KSHV antigens by the immunoblot assay, as compared with only 7 of 40 homosexual men (18 percent) without Kaposi's sarcoma immediately before the onset of AIDS. Of 122 blood donors, 22 EBV-infected patients, and 20 HIV-infected men with hemophilia, none were seropositive. When studied by the immunoblot assay over a period of 13 to 103 months, 21 of the 40 patients with Kaposi's sarcoma (52 percent) seroconverted 6 to 75 months before the clinical appearance of Kaposi's sarcoma. The median duration of antibody seropositivity for KSHV-related latent nuclear antigens before the diagnosis of Kaposi's sarcoma was 33 months.

CONCLUSIONS

In most patients with kaposi's sarcoma and AIDS, seroconversion to positivity for antibodies against KSHV-related nuclear antigens occurs before the clinical appearance of Kaposi's sarcoma. This supports the hypothesis that Kaposi's sarcoma results from infection with KSHV.

Detection of a nuclear antigen 2 (EBNA2)-variant Epstein-Barr virus strain in two siblings with fatal lymphoproliferative disease

An EBV type 1 variant strain was detected in two Turkish siblings (boy and girl), who both suffered and died from similar progressive Epstein-Barr virus (EBV)-associated lymphoproliferative disease. Molecular characterisation of this EBV isolate revealed a 51bp-deletion and six nucleotide changes within the Epstein-Barr nuclear antigen 2 (EBNA2). Both isolates contained EBV type 2 sequences in the Epstein-Barr virus-encoded small RNAs (EBER), which are 40 kb proximal to EBNA2. Sequencing of the EBV isolates in a region of Epstein-Barr nuclear antigen 3 (EBNA3a), which is 40 kb distal to EBNA2, revealed the normal EBV type 1 sequence of laboratory strain B95-8. This EBV isolate may represent a distinct wild type EBV strain with altered biological properties. It is suggested that this EBNA2-variant strain may be responsible at least in part for the severe clinical course in both affected children.

Immune regulation in Epstein-Barr virus-associated diseases

Epstein-Barr virus (EBV) is a member of the human herpesvirus family and, like many other herpesviruses, maintains a lifelong latent association with B lymphocytes and a permissive association with stratified epithelium in the oropharynx. Clinical manifestations of primary EBV infection range from acute infectious mononucleosis to an asymptomatic persistent infection. EBV is also associated with a number of malignancies in humans. This review discusses features of the biology of the virus, both in cell culture systems and in the natural host, before turning to the role of the immune system in controlling EBV infection in healthy individuals and in individuals with EBV-associated diseases. Cytotoxic T cells that recognize virally determined epitopes on infected cells make up the major effector arm and control the persistent infection. In contrast, the options for immune control of EBV-associated malignancies are more restricted. Not only is antigen expression restricted to a single nuclear antigen, EBNA1, but also these tumor cells are unable to process EBV latent antigens, presumably because of a transcriptional defect in antigen-processing genes (such as TAP1 and TAP2). The likelihood of producing a vaccine capable of controlling the acute viral infection and EBV-associated malignancies is also discussed.

Hodgkin's disease as an indicator of AIDS

Hodgkin's disease (HD) is not currently included within the Centers for Disease Control (CDC) classification system for AIDS. Upon HD diagnosis, HIV(human immunosuppressive virus)-positive patients are generally found within Stages III or IV of the Ann Arbor HD classification system, already exacerbating the problem of treatment. In contrast, HIV-negative patients diagnosed with HD are generally found within Stages I or II. Epidemiology and the presence of secondary lymphomas, opportunistic infections, or aggressive pathologies, accompanied by low survival rate and timing of HD diagnosis suggest that HD should be included among conditions indicating AIDS manifestation.

Development of a recombinant enzyme-linked immunosorbent assay for detection of antibodies against Epstein-Barr virus nuclear antigens 2A and 2B

The baculovirus expression system was used to produce full-length Epstein-Barr virus nuclear antigens (EBNAs) 2A and 2B. Recombinant baculoviruses that contained the EBNA-2A- and EBNA-2B-encoding sequences were constructed. The proteins were expressed in Spodoptera frugiperda SF-9 cells infected with the recombinant viruses and were characterized by using monoclonal and human polyclonal antibodies by immunoblotting and immunofluorescence techniques. Partially purified extracts of the EBNA-2A- and EBNA-2B-infected insect cells were used to establish a new enzyme-linked immunosorbent assay for the detection of antibodies against EBNA-2A and EBNA-2B. Preferential reactivity toward the type A or type B EBNA-2 protein was observed in 36% of serum specimens from Swiss patients with acute infectious mononucleosis and in 81% of Swiss patients with latent Epstein-Barr virus infection. Of the patients in the latter group, sera from 76% reacted preferentially with EBNA-2A, sera from 5% reacted preferentially with EBNA-2B, sera from 12% showed similar reactivities against both antigens, and sera from 7% were nonreactive.

Epstein-Barr virus infection in liver transplantation patients: correlation of histopathology and semiquantitative Epstein-Barr virus-DNA recovery using polymerase chain reaction

Epstein-Barr virus (EBV) infection may complicate orthotopic liver transplantation, and can lead to hepatitis with subsequent graft failure and to benign and malignant lymphoproliferative disorders. Early diagnosis allows for prevention or treatment of complications. Histopathologic features of EBV infection in the liver vary and may be difficult to recognize. To delineate the morphologic features that allow for recognition we studied 61 biopsy specimens from 37 patients, correlating the results of EBV-DNA demonstration after polymerase chain reaction with histopathology of formalin-fixed, hematoxylin-eosin-stained liver biopsy specimens. DNA was extracted from fresh liver biopsy samples, and polymerase chain reaction was carried out with EBV primers (capsid protein gp220) using standard techniques and 25-cycle amplification. Epstein-Barr virus-related sequences after polymerase chain reaction were detected by DNA blot assay. Histopathologic features were classified into three categories on the basis of the semiobjective determination of the number and distribution of immunoblasts and other immature lymphocytes in portal tracts and sinusoids: highly suggestive (three biopsy specimens), indeterminant (one biopsy specimen), and negative (57 biopsy specimens). Only the three highly suggestive biopsy specimens had high levels of EBV-DNA. We conclude that the histopathologic features of EBV infection after orthotopic liver transplantation can be relied on to establish the diagnosis.

Increased risk of malignant lymphoma indicated by elevated Epstein-Barr virus antibodies--a prospective study

We estimated Epstein-Barr virus (EBV) antibody-associated relative risks (RR) of malignant lymphoma/leukemia within a cohort of 39,000 healthy Finnish adults followed up for 12 years. Antibody analyses to EBV capsid antigen (VCA), early antigen (EA), and nuclear antigens (EBNA, EBNA1, and EBNA2) were based on concomitantly evaluated ELISA techniques. No increased risk was associated with mere EBV seropositivity. However, elevated EBV EA and EBNA antibody levels were associated with a statistically significant excess risk of malignant lymphoma/leukemia (RREA = 3.4, 95 percent confidence interval [CI] = 1.0-11.0; RREBNA = 4.5, CI = 1.2-16.9). These elevated antibody responses may be due either to destruction of neoplastic EBV positive B-cells and/or to activation of latent EBV infection early in the lymphomagenesis.

Expression of Epstein-Barr virus nuclear antigen 1,2A and 2B in the baculovirus expression system: serological evaluation of human antibodies to these proteins

The Epstein-Barr virus encoded nuclear antigens 1,2A, and 2B (EBNA 1, EBNA 2A, and EBNA 2B) were expressed in a baculovirus system. The full length recombinant proteins were recognized by polyclonal rabbit sera and by human sera. An immunofluorescence (IF) test for the differentiation between EBNA 1 and EBNA 2 antibodies in human sera was established with the expressed proteins. None of 55 sera of patients with infectious mononucleosis (IM) had anti-EBNA 1 antibodies while 36 of these sera had anti-EBNA 2A antibodies. Conversely, 47 of 51 sera from EBV-positive healthy carriers had anti-EBNA 1 antibodies and 18 of these sera had anti-EBNA 2A antibodies. The sensitivity and specificity of the EBNA 1 IF for the diagnosis of IM were higher as compared to conventional anti-complement immunofluorescence (ACIF). In the IF test differentiation between type A and type B EBV infection was only possible in sera from the IM patients. An immunoblot (IB) with low amounts of baculovirus expressed EBNA 2A and EBNA 2B antigen was carried out. Twenty-nine of 31 sera from IM patients or from healthy carriers with EBNA 2 antibodies reacted predominantly with EBNA 2A, whereas a known type B serum reacted strongly with EBNA 2B than with EBNA 2A.

Epstein-Barr virus infection and associated diseases in children. II. Diagnostic and therapeutic strategies

Epstein-Barr virus (EBV), an ubiquitous human B lymphotropic virus, is the cause of infectious mononucleosis. Moreover, EBV infection can be followed by lymphoproliferative diseases in patients with inherited and acquired immunodeficiencies. Primary EBV infection may be a threat to all children after marrow or organ transplantation or those receiving chronic immunosuppressive treatment for various other reasons. The virus has been also implicated in the pathogenesis of different malignant tumours such as Burkitt lymphoma, nasopharyngeal carcinoma, Hodgkin disease and also some T-cell lymphomas. This review focuses on various aspects of virus-host interactions, immune mechanisms of the host, and the still experimental therapeutic approaches in EBV-associated diseases.

Use of enzyme-linked immunosorbent assays with chimeric fusion proteins to titrate antibodies against Epstein-Barr virus nuclear antigen 1

Two new enzyme-linked immunosorbent assays (ELISAs) with chimeric fusion polypeptides for the detection of human antibodies specific to Epstein-Barr virus nuclear antigen 1 (EBNA-1) are described. One is an indirect ELISA with affinity-purified beta-galactosidase-EBNA-1 fusion protein as the antigen. The other is a "sandwich" assay based on the use of anti-beta-galactosidase antibody to capture beta-galactosidase-EBNA-1 fusion proteins in bacterial extracts. A good correlation was shown between antibody titers determined by the ELISA with the EBNA-1 fusion proteins and those determined by a conventional anticomplement immunofluorescence test which is being widely performed with Raji cells for the purpose of research and clinical diagnosis. The advantage of the ELISAs for seroepidemiologic studies on Epstein-Barr virus was demonstrated by sensitive detection of marginal immunoglobulin G antibody to the EBNA-1 domain in serum samples from patients with infectious mononucleosis.

Anti-Epstein-Barr virus-nuclear antigen-1, -2A and -2B antibodies in rheumatoid arthritis patients and their relatives

We have examined serum antibodies to Epstein-Barr virus Nuclear Antigen (EBNA)-1, -2A and -2B, in addition to antibodies to viral capsid antigen and early antigen in 100 rheumatoid arthritis patients and 50 of their relatives. Using indirect immunofluorescence on transfected cells and Western-blot technique, we have found increased frequency and titres of antibodies to EBNA-2B in patients and, to a lesser degree, in their family members, whereas other anti-Epstein-Barr virus antibodies appeared to be similar to controls. Cross-inhibition experiments were carried out and show that antibodies to EBNA-2A are distinct from those to -2B, and vice versa.

Regulated expression of Epstein-Barr virus nuclear antigen 3-encoding gene carried on stable episomal vectors in human cells

Recently a small number of Epstein-Barr viral (EBV) genes, characteristically expressed in latently infected, growth-transformed B-lymphocytes, have been cloned and several have been transiently expressed by DNA transfection. Here we demonstrate production of stable human cell lines containing episomal EBV vectors and expressing EBV nuclear antigen 3 from the adenovirus major late promoter or the mouse metallothionein promoter, which retains metal-regulation in the episomal state. This system has proved useful in an analysis of the role of these and other EBV genes implicated in immortalization and/or oncogenic transformation of human cells.

Relationship between clinical stage, histopathology and antibody titers against the second Epstein-Barr virus nuclear antigen (EBNA-2) in non-Hodgkin's lymphoma patients

Non-Hodgkin lymphoma (NHL) patients with centroblastic (Cb) or centroblastic-centrocytic (Cb/Cc)-diffuse lymphomas, immunocytoma (IC) and chronic lymphocytic leukemia (CLL) in clinical stages III-IV and with active disease (highly malignant group) were compared to NHL patients with CLL, IC, and centrocytic (Cc) or centroblastic-centrocytic (Cb-Cc)-diffuse/follicular lymphomas, in clinical stages I-II and with inactive disease (low malignant group) based on the presence of antibodies to Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA-1) and 2 (EBNA-2). In the highly malignant group, anti-EBNA-1 geometric mean titers (GMT) were 13.2 (range less than 2-80) and anti-EBNA-2 60.6 (range: 20-320). The ratio between the logarithms of anti-EBNA-1 and anti-EBNA-2 antibody titers was less than 1.0 (mean: 0.32) in all the patients examined. In 6 out of 8 patients of the low malignant group, anti-EBNA-1 titers were higher (mean: 30.1; range 10-160) than anti-EBNA-2 titers (mean: 4.3; range less than 2-80) and the EBNA 1/2 ratio was greater than 1.0. In healthy EBV-seropositive individuals, anti-EBNA-1 GMT were 49 (range: 10-320) and only 5 out of 17 individuals had detectable anti-EBNA-2 titers (GMT: 3; range less than 5-20). The EBNA-1/2 ratio was in all cases greater than 1. Among patients of the highly and low malignant groups, patients with follicular-cell-derived lymphomas had elevated antibody titers against the restricted component of early antigens (EA-R), whereas all patients with IC and 2 out of 4 CLL patients had elevated antibody titers against the diffuse component of early antigens (EA-D). The results indicate that the ratio between anti-EBNA-1 and anti-EBNA-2 antibody titers may be of diagnostic importance in patients with immunodeficiencies.