Study of Epstein Barr virus (EBV) antibodies: IgG and IgM anti-VCA, IgG anti-EA and Ig anti-EBNA obtained with an original microtiter technique: --serological criterions of primary and recurrent EBV infections and follow-up of infectious mononucleosis--seroepidemiology of EBV in Belgium based on 5178 sera from patients

Increased antibody levels to stage-specific Epstein-Barr virus antigens in systemic autoimmune diseases reveal a common pathology

The immune responses to antigens from different stages of the Epstein-Barr virus (EBV) life cycle were investigated in systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjögren's syndrome (SS), and systemic sclerosis (SSc) to gain knowledge of EBV's involvement in the etiology of systemic autoimmune diseases (SADs) and for an overview of the humoral immune responses against EBV. Investigations were performed by the use of ELISA. IgM, IgA, and IgG antibody binding to 11 EBV antigens: EBNA1, EBNA2, BALF5, EAD, BALF2, EA/R, VCA p18, VCA p23, gB, gp350, and gp42 were examined in serum pools from SAD patients and healthy controls (HCs). Increased antibody levels against the 11 EBV antigens in the SAD pools were seen compared to the HC pool. Specifically, SLE was characterized by strongly increased IgA to EAD both compared to HCs and other SADs, and RA was characterized by increased IgM levels to several EBV antigens. The SADs may be partly distinguished by their differential immune responses to various antigens in the EBV life cycle. All together, these findings support an association between EBV infection and SADs.

Modeling of EBV Infection and Antibody Responses in Kenyan Infants With Different Levels of Malaria Exposure Shows Maternal Antibody Decay is a Major Determinant of Early EBV Infection

The combination of Epstein-Barr virus (EBV) infection and high malaria exposure are risk factors for endemic Burkitt lymphoma, and evidence suggests that infants in regions of high malaria exposure have earlier EBV infection and increased EBV reactivation. In this study we analyzed the longitudinal antibody response to EBV in Kenyan infants with different levels of malaria exposure. We found that high malaria exposure was associated with a faster decline of maternally derived immunoglobulin G antibody to both the EBV viral capsid antigen and EBV nuclear antigen, followed by a more rapid rise in antibody response to EBV antigens in children from the high-malaria-transmission region. We also observed the long-term persistence of anti-viral capsid antigen immunoglobulin M responses in children from the high-malaria region. More rapid decay of maternal antibodies was a major predictor of EBV infection outcome, because decay predicted time to EBV DNA detection, independent of high or low malaria exposure.

Serological diagnosis of Epstein-Barr virus infection: Problems and solutions

Serological tests for antibodies specific for Epstein-Barr virus (EBV) antigens are frequently used to define infection status and for the differential diagnosis of other pathogens responsible for mononucleosis syndrome. Using only three parameters [viral capsid antigen (VCA) IgG, VCA IgM and EBV nuclear antigen (EBNA)-1 IgG],it is normally possible to distinguish acute from past infection: the presence of VCA IgM and VCA IgG without EBNA-1 IgG indicates acute infection, whereas the presence of VCA IgG and EBNA-1 IgG without VCA IgM is typical of past infection. However, serological findings may sometimes be difficult to interpret as VCA IgG can be present without VCA IgM or EBNA-1 IgG in cases of acute or past infection, or all the three parameters may be detected simultaneously in the case of recent infection or during the course of reactivation. A profile of isolated EBNA-1 IgG may also create some doubts. In order to interpret these patterns correctly, it is necessary to determine IgG avidity, identify anti-EBV IgG and IgM antibodies by immunoblotting, and look for heterophile antibodies, anti-EA (D) antibodies or viral genome using molecular biology methods. These tests make it possible to define the status of the infection and solve any problems that may arise in routine laboratory practice.

Association between Epstein-Barr virus and Hodgkin's lymphoma in Belgium: a pathological and virological study

The association between Epstein-Barr virus (EBV) and classical Hodgkin's lymphoma (cHL) varies according to the geographic location. In this work we sought to characterize EBV involvement in a series of 111 cHL cases diagnosed in Belgium. The overall prevalence of EBV infection detected by in situ hybridization in Reed-Sternberg cells was 33%. EBV positivity correlated with older age at diagnosis (>54 years; p = 0.01), mixed cellularity subtype (p = 0.000001), male gender (p = 0.004) and tended to be associated with higher clinical stage (III/IV; p = 0.02). The molecular features of the virus in EBV-positive cHL were studied by comparison with a series of reactive tonsils. A 30-bp deletion within the LMP-1 gene was in 15/28 (53.6%) EBV-positive cHL cases, and in 41.7% of reactive tonsil samples. This variant did not correlate with any clinical or pathological feature. The EBV strain was type A in all cHL and reactive samples.

Prevalence of viral and mycobacterial co-infections in perinatally HIV-infected children

The progression of HIV disease may be affected by co-infection with other viruses. This study investigates the prevalence of Epstein-Barr virus (EBV); cytomegalovirus (CMV); herpes simplex virus (HSV) types 1 and 2; hepatitis A, B, and C (HA, HB, HC); and tuberculosis in perinatally HIV-infected children. Electrochemiluminescence Immunoassay (EIA) against EBV, CMV, HSV 1 and 2, HAV HBV HCV, and skin testing with purified protein derivative was performed on 45 perinatally HIV-infected children. CMVwas positive in 51%, EBVin 93.3%, HSV-1 in 62.2%, HSV-2 in 48.9%, HAV in 15.6%, HBVand HCV in 6.7% and PPD in 0%. HSV-2 prevalence was higher in females and Hispanics. The prevalence of CMV, EBV HSV-1, and tuberculosis was equivalent to rates reported in the general population. Prevalence of HSV-2 was significantly higher than in the general population (p < 0.001). Higher rates of HSV-2 infection and hepatitis may be secondary to high maternal co-infection rate and subsequent vertical transmission.

Differentiation of primary from secondary anti-EBNA-1-negative cases by determination of avidity of VCA-IgG

BACKGROUND

Serological techniques are used to determine Epstein Barr virus (EBV) etiology of a constellation of signs or symptoms related to lymphadenopathy, fever, respiratory tract infection, mononucleosis, hepatitis, thrombocytopenia or neurological disorder. Anti-Epstein Barr Nuclear antigen (EBNA)-1 is regularly negative during the first 3-4 weeks after the onset of clinical symptoms indicating acute EBV infection (primary anti-EBNA-1-negative). It may, however, also be negative in immunocompromised convalescent individuals (secondary anti-EBNA-1-negative) such as tumor patients, HIV-positive patients and transplant recipients.

OBJECTIVES

The aim of this study was to determine the frequency of secondary anti-EBNA-1-negative cases and to find a way to distinguish them from primary anti-EBNA-1-negative cases using anticomplementary immunofluorescence (ACIF) and enzyme immunoassay (EIA).

STUDY DESIGN

All sera sent to our institute for EBV serology during one year were routinely tested for Viral Capsid antibody (VCA)-IgM, VCA-IgG and anti-EBNA-1.

RESULTS

VCA-IgG-positive/anti-EBNA-1-negative cases (13.5% of total VCA-IgG-positive) comprised 55% primary and 45% secondary anti-EBNA-1-negative cases. Detection of secondary anti-EBNA-1-negative cases was independent of the method used, i.e., ACIF or EIA. VCA-IgG retained its high avidity in secondary anti-EBNA-1-negative cases, whereas primary anti-EBNA-1-negative cases taken during the early phase of acute infection showed low avidity of VCA-IgG.

CONCLUSION

Determination of the avidity of VCA-IgG routinely and in concert with standard serodiagnosis (VCA-IgG, VCA-IgM, anti-EBNA-1) can enable the differentiation of primary and secondary anti-EBNA-1-negative cases.

Epstein-Barr virus infection is not associated with development of allergy in children

BACKGROUND

Differences in concentrations of antibodies to Epstein-Barr virus (EBV) in atopic and nonatopic children have been observed, suggesting that EBV infection may play a role in allergic diseases. AIM To assess the association between EBV infection and atopy in Swedish children at 4 years of age.

MATERIALS AND METHODS

Were studied 2561 children born in 1994 through 1996 in Stockholm, Sweden. The children were enrolled in a prospective birth cohort study focusing on the relation of exposure to various environmental and life style factors during early childhood and development of atopy. Blood samples were obtained when the children were approximately 4 years old, and immunoglobulin G to EBV was determined by indirect immunofluorescence. The relationship between the seroprevalence to EBV and various allergic disorders was assessed, withthe use of logistic regression analysis to account for other risk factors.

RESULTS

Totally 1347 of 2561 (52%) children were EBV-seropositive. Associations between EBV seropositivity and the occurrence of asthma [adjusted odds ratio (OR(adj)), 1.10; 95% confidence interval (95% CI) 0.81 to 1.49] or suspected allergic rhinitis (OR(adj) 0.97; 95% CI 0.76 to 1.25) were not apparent. In children whose mothers were up to 25 years old, a higher EBV seroprevalence was observed than in children of older mothers (OR(adj) 1.34; 95% CI 1.04 to 1.71). Also in children whose mothers smoked, the seroprevalence was higher than in children of nonsmokers (OR(adj) 1.29; 95% CI 1.02 to 1.63).

CONCLUSIONS

The study does not support the hypothesis that EBV infection in early childhood plays an important role in the pathogenesis of allergic diseases in children.

A systematic study of Epstein-Barr virus serologic assays following acute infection

We determined the presence of IgG and IgM antibody to viral capsid antigen (VCA-IgG, VCA-IgM) and IgG antibody to the Epstein-Barr virus nuclear antigen (EBNA) by indirect immunofluorescence assay (IFA) and enzyme-linked immunosorbent assay (ELISA) during the acute illness and at 1, 2, 6, and 48 months in a prospective population-based case series of 95 persons with an acute illness serologically confirmed as Epstein-Barr virus infection. The acute illness was characterized by the presence of VCA-IgG and VCA-IgM (by ELISA) and by the absence of EBNA in most, but not all, patients. During follow-up, VCA-IgG antibodies remained detectable in all patients, while the proportion with VCA-IgM declined and the number with detectable EBNA antibodies steadily increased. The primary differences between the 2 serologic test methods were the increased persistence of VCA-IgM during follow-up by ELISA and the earlier detection of EBNA by IFA. Clinicians should consider the illness stage and the laboratory technique to appropriately interpret serologic test results in suspected cases of mononucleosis caused by the Epstein-Barr virus.

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 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.

Viral serologies in patients with chronic fatigue and chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is an illness characterized by disabling fatigue associated with complaints of fevers, sore throat, myalgia, lymphadenopathy, sleep disturbances, neurocognitive difficulties, and depression. A striking feature of CFS is its sudden onset following an acute, presumably viral, illness and the subsequent recurrent "flu-like" symptoms. It has been speculated that both CFS and debilitating chronic fatigue (CF) that does not meet strict criteria for CFS may be the direct or indirect result of viral infections. We therefore tested 548 chronically fatigued patients who underwent a comprehensive medical and psychiatric evaluation for antibodies to 13 viruses. Our objectives were to compare the seroprevalence and/or geometric mean titer (GMT) of antibodies to herpes simplex virus 1 and 2, rubella, adenovirus, human herpesvirus 6, Epstein-Barr virus, cytomegalovirus, and Cox-sackie B virus, types 1-6 in patients with CF to healthy control subjects. Other goals were to determine if greater rates of seropositivity or higher GMTs occurred among subsets of patients with CFS, fibromyalgia, psychiatric disorders, a self-reported illness onset with a viral syndrome, and a documented temperature > 37 degrees C on physical examination. Differences in the seroprevalence or GMTs of antibodies to 13 viruses were not consistently found in those with CF compared with control subjects, or in any subsets of patients including those with CFS, an acute onset of illness, or a documented fever. These particular viral serologies were not useful in evaluating patients presenting with CF.

Fibromyalgia and chronic fatigue syndrome: similarities and differences

CFS and FM are clinical conditions characterized by a variety of nonspecific symptoms including prominent fatigue, myalgia, and sleep disturbances. There are no diagnostic studies or widely accepted, pathogenic, explanatory models for either illness. Despite remarkably different diagnostic criteria, CFS and FM have many demographic and clinical similarities. More specifically, few differences exist in the domains of symptoms, examination findings, laboratory tests, functional status, psychosocial features, and psychiatric disorders. FM appears to represent an additional burden of suffering among those with CFS, however, underscoring the importance of recognizing concurrent CFS and FM. Further clarification of the similarities (and differences) between CFS and FM may be useful in studies of prognosis and help define subsets of patients who may benefit from specific therapeutic interventions.

Epstein-Barr virus infection and associated diseases in children. I. Pathogenesis, epidemiology and clinical aspects

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 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.

Epstein-Barr virus as a cause of autoimmune disease and other medical morbidity in patients with affective disorders

We hypothesize that psychiatric patients suffering from the major affective disorders (depression and manic-depressive illness) may commonly also suffer from a chronic active infection with the Epstein-Barr virus. This infection would be a consequence of the immune dysfunction known to be associated with these disorders of mood. According to this hypothesis, the increased medical morbidity and mortality reported in these psychiatric patients would be attributable in part to diseases in which Epstein-Barr virus is implicated or suspected as a cause.

Rapid diagnosis of acute Epstein-Barr virus infection by an indirect enzyme-linked immunosorbent assay for specific immunoglobulin M (IgM) antibody without rheumatoid factor and specific IgG interference

An indirect enzyme-linked immunosorbent assay (ELISA) for detection of Epstein-Barr virus-specific immunoglobulin M (IgM) antibody was developed with commercial reagents. Sera containing rheumatoid factor (RF) (as little as 0.5 IU/ml) coupled with specific IgG resulted in false-positives in the ELISA. This interference was eliminated by the use of anti-human IgG antibodies to remove RF and IgG. Thus, pathogen-specific IgG complexes to which IgM-RF could be bound during the subsequent test were inhibited, and competition between specific IgG and IgM was also prevented. Of the 1,672 serum specimens tested, 353 were found to be Epstein-Barr virus IgM antibody positive by indirect immunofluorescence (IF). Compared with the IF test, the ELISA showed 96.6% sensitivity, 99.7% specificity, and 99% accuracy. Further evidence indicated that most of the 12 ELISA false-negatives were IF false-positives. There was a linear correlation between mean ELISA values and increasing IF titers (r = 0.96). However, the IF test has the disadvantages that it lacks automated reading and requires considerable technical expertise, both of which restrict the range of laboratories performing the test. The indirect ELISA has the advantages that it is simple and rapid and can be automated. All the reagents used in this assay are commercially available, have been prestandardized, and are stable.

Subclass reactivity to Epstein-Barr virus capsid antigen in primary and reactivated EBV infections

A new method for analysis of virus-specific Immunoglobulin G (IgG) subclasses was developed using indirect immunofluorescence. Three hundred thirty-three serum samples from patients with different types of Epstein-Barr virus (EBV)-associated diseases and healthy controls were examined for subclass distribution to the virus capsid antigen (EBV VCA). EBV-VCA-expressing cell preparations were incubated with patient serum followed by monoclonal antibodies to human IgG1 through IgG4 and labelled anti-mouse IgG. Virus-specific IgG1 was found to be the dominant antibody. The titers for IgG1 and total Ig to EBV VCA correlated well. EBV VCA-specific IgG2 was not found. EBV VCA-specific IgG3 in a titer of greater than or equal to 10 was found in 33% of healthy seropositive donors, in 97% of patients with suspected reactivated EBV infection, and in 100% of symptomatic patients with suspected reactivated EBV infection. EBV VCA specific IgG3 occurred in 90% of placebo-treated compared to 30% in long-term acyclovir-treated bone marrow transplant recipients, indicating more frequent reactivations in the former group. IgG4 to VCA was infrequently found in seropositive persons. In serum samples from patients with nasopharyngeal carcinoma and high EBV VCA Ig and IgA titers, IgG4 to VCA was always present. Analysis of EBV VCA specific IgG subclasses seems to be valuable for the diagnosis of reactivated EBV infection.

Assessment of serologic markers for Epstein-Barr virus

Antibody responses to early antigen (EA) and viral capsid antigen (VCA) were analyzed in 48 proven cases of Epstein-Barr Virus infection and in 48 age- and sex-matched healthy controls to establish optimal cutoff values for diagnosing EBV infection. Predictive values were determined for individual EA and VCA antibody titers and for EA to VCA antibody ratios and the optimal dilution cutoff values for positivity of EA (1:20), VCA (1:640), and EA to VCA (0:031) were selected. When evaluated on a subset of 10 VCA IgM positive cases and 35 negative controls, the three selected cutoff values identified as infections nine of 10, four of 10, and 10 of 10 of the cases and one of 35, none of 35, and one of 35 of the controls, respectively. When evaluated individually on 22 cases of suspected EBV infection who were heterophile antibody-negative and presented with symptoms compatible with EBV infection, an equal number of VCA IgM-positive and negative cases were identified as EBV infections. Overall, the cutoffs EA, VCA, and ratio identified 19 of 22 (86.4%), 14 of 22 (63.6%), and 18 of 22 (81.8%), respectively, and all cases could be identified using combinations of these values. Although these serologic values may be used with some accuracy, until more definitive markers are described a combination of heterophile responses, lymphocyte analysis, clinical symptoms, and serologic cutoff values should be used to assess the role of EBV in patient evaluation.