Antibody responses to Epstein-Barr virus-determined nuclear antigen (EBNA)-1 and EBNA-2 in acute and chronic Epstein-Barr virus infection

Investigation of atypical serological profiles for Epstein-Barr virus (EBV)

BACKGROUND

Commercial immunoassays that detect IgG and IgM directed toward VCA and IgG EBNA are used in combination to assess EBV immune status. However, this strategy does not always confirm/exclude recent/past EBV infection or absence of immunity.

OBJECTIVES

The aim of our study was to perform complementary investigations on samples with atypical EBV serological profiles, in order to identify the clinical situation they correspond to.

STUDY DESIGN

EBV serology was performed using EBV VCA IgM/IgG and EBNA IgG LXL® DiaSorin assay. Complementary investigations included ELISA IgM VCA, immunoblots, CMV IgM/IgG and CMV IgG avidity, and EBV PCR.

RESULTS

In our study, 12810 EBV serological results were analyzed, and 3580 atypical profiles were detected (28 %). Among these latter, isolated VCA IgG represented 42.9 %, the three positive markers accounted for 29.1 %, isolated EBNA IgG represented 18.5 %, isolated VCA IgM accounted for 6.4 % and positive VCA IgM & positive EBNA IgG represented 3.1 %. VCA IgG detected alone were specific in 100 % cases and EBNA IgG detected alone were specific in 91.7 % cases. VCA IgM detected alone were false positive or due to a cross reaction with CMV in 52.8 % cases. The pattern positive VCA IgM and positive EBNA IgG correspond to a false positive in VCA IgM, EBNA IgG or both in 83.4 % cases. Positive EBV VCA IgM/IgG and EBNA IgG were unreliable to detect active EBV infection in 66.7 % cases.

DISCUSSION

Atypical EBV serological profiles may correspond to several clinical situations and complementary investigations allow to determine the immune status in more than 98.5 % cases.

Heightened Epstein-Barr virus immunity and potential cross-reactivities in multiple sclerosis

BACKGROUND

Epstein-Barr virus (EBV) is a likely prerequisite for multiple sclerosis (MS) but the underlying mechanisms are unknown. We investigated antibody and T cell responses to EBV in persons with MS (pwMS), healthy EBV-seropositive controls (HC) and post-infectious mononucleosis (POST-IM) individuals up to 6 months after disease resolution. The ability of EBV-specific T cell responses to target antigens from the central nervous system (CNS) was also investigated.

METHODS

Untreated persons with relapsing-remitting MS, POST-IM individuals and HC were, as far as possible, matched for gender, age and HLA-DRB1*15:01. EBV load was determined by qPCR, and IgG responses to key EBV antigens were determined by ELISA, immunofluorescence and Western blot, and tetanus toxoid antibody responses by multiplex bead array. EBV-specific T cell responses were determined ex vivo by intracellular cytokine staining (ICS) and cross-reactivity of in vitro-expanded responses probed against 9 novel Modified Vaccinia Ankara (MVA) viruses expressing candidate CNS autoantigens.

RESULTS

EBV load in peripheral blood mononuclear cells (PBMC) was unchanged in pwMS compared to HC. Serologically, while tetanus toxoid responses were unchanged between groups, IgG responses to EBNA1 and virus capsid antigen (VCA) were significantly elevated (EBNA1 p = 0.0079, VCA p = 0.0298) but, importantly, IgG responses to EBNA2 and the EBNA3 family antigens were also more frequently detected in pwMS (EBNA2 p = 0.042 and EBNA3 p = 0.005). In ex vivo assays, T cell responses to autologous EBV-transformed B cells and to EBNA1 were largely unchanged numerically, but significantly increased IL-2 production was observed in response to certain stimuli in pwMS. EBV-specific polyclonal T cell lines from both MS and HC showed high levels of autoantigen recognition by ICS, and several neuronal proteins emerged as common targets including MOG, MBP, PLP and MOBP.

DISCUSSION

Elevated serum EBV-specific antibody responses in the MS group were found to extend beyond EBNA1, suggesting a larger dysregulation of EBV-specific antibody responses than previously recognised. Differences in T cell responses to EBV were more difficult to discern, however stimulating EBV-expanded polyclonal T cell lines with 9 candidate CNS autoantigens revealed a high level of autoreactivity and indicate a far-reaching ability of the virus-induced T cell compartment to damage the CNS.

A high-throughput neutralizing assay for antibodies and sera evaluation against Epstein-Barr virus

BACKGROUND

Epstein-Barr virus (EBV) is a wide-spread human herpesvirus that is highly associated with infectious mononucleosis and several malignancies. Evaluation of EBV neutralizing antibody titers is important for serological studies, vaccine development and monoclonal antibody screening. The traditional method based on antibody inhibition of EBV transformation of B cells is very time-consuming. A more practical flow cytometry-based (FCM) approach to evaluate neutralizing titers is not amenable to achieving high-throughput evaluation of large-scale samples. A high-throughput approach is urgently needed.

RESULTS

Here, we present a rapid and high-throughput method based on high content imaging system (HCIS) analysis. EBV titers determined by the HCIS-based assay were similar to those obtained by the FCM-based assay. Neutralizing titers of sera and monoclonal antibodies measured by the HCIS-based assay strongly correlated with titers measured by the FCM-based assay. HCIS assays showed a strong correlation between B cell infection neutralizing titers and the anti-gp350 IgG titers in healthy EBV carriers and monkey sera. Finally, anti-gHgL IgG titers from sera of healthy EBV carriers significantly correlated with epithelial cell infection neutralizing titers.

CONCLUSIONS

This HCIS-based assay is a high-throughput assay to determine viral titers and evaluate neutralizing potentials of sera and monoclonal antibodies. This HCIS-based assay will aid the development of vaccines and therapeutic monoclonal antibody against EBV.

Longitudinal analysis reveals high prevalence of Epstein-Barr virus associated with multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system of unknown etiology. We tested the hypothesis that MS is caused by Epstein-Barr virus (EBV) in a cohort comprising more than 10 million young adults on active duty in the US military, 955 of whom were diagnosed with MS during their period of service. Risk of MS increased 32-fold after infection with EBV but was not increased after infection with other viruses, including the similarly transmitted cytomegalovirus. Serum levels of neurofilament light chain, a biomarker of neuroaxonal degeneration, increased only after EBV seroconversion. These findings cannot be explained by any known risk factor for MS and suggest EBV as the leading cause of MS.

Prophylactic and Therapeutic EBV Vaccines: Major Scientific Obstacles, Historical Progress, and Future Direction

The Epstein-Barr virus (EBV) infects more than 95% of adults worldwide and is associated with various malignant tumors and immune diseases, imparting a huge disease burden on the human population. Available EBV vaccines are imminent. Prophylactic vaccines can effectively prevent the spread of infection, whereas therapeutic vaccines mainly stimulate cell-mediated immunity and kill infected cells, thus curbing the development of malignant tumors. Nevertheless, there are still no approved EBV vaccines after decades of effort. The complexity of the EBV life cycle, the lack of appropriate animal models, and the limited reports on adjuvant selection and immune responses are gravely impeding progress in EBV vaccines. The soluble gp350 vaccine could reduce the incidence of infectious mononucleosis (IM), which seemed to offer hope, but could not prevent EBV infection. Continuous research and vaccine trials provide deep insights into the structural biology of viruses, the designs for immunogenicity, and the evolving vaccine platforms. Moreover, the new vaccine candidates are expected to achieve further success via combined immunization to elicit both a dual protection of B cells and epithelial cells, and sustainable immunization against infected cells at several phases of infection.

Affinity Tag Coating Enables Reliable Detection of Antigen-Specific B Cells in Immunospot Assays

Assessment of humoral immunity to SARS-CoV-2 and other infectious agents is typically restricted to detecting antigen-specific antibodies in the serum. Rarely does immune monitoring entail assessment of the memory B-cell compartment itself, although it is these cells that engage in secondary antibody responses capable of mediating immune protection when pre-existing antibodies fail to prevent re-infection. There are few techniques that are capable of detecting rare antigen-specific B cells while also providing information regarding their relative abundance, class/subclass usage and functional affinity. In theory, the ELISPOT/FluoroSpot (collectively ImmunoSpot) assay platform is ideally suited for antigen-specific B-cell assessments since it provides this information at single-cell resolution for individual antibody-secreting cells (ASC). Here, we tested the hypothesis that antigen-coating efficiency could be universally improved across a diverse set of viral antigens if the standard direct (non-specific, low affinity) antigen absorption to the membrane was substituted by high-affinity capture. Specifically, we report an enhancement in assay sensitivity and a reduction in required protein concentrations through the capture of recombinant proteins via their encoded hexahistidine (6XHis) affinity tag. Affinity tag antigen coating enabled detection of SARS-CoV-2 Spike receptor binding domain (RBD)-reactive ASC, and also significantly improved assay performance using additional control antigens. Collectively, establishment of a universal antigen-coating approach streamlines characterization of the memory B-cell compartment after SARS-CoV-2 infection or COVID-19 vaccinations, and facilitates high-throughput immune-monitoring efforts of large donor cohorts in general.

Guillain-Barré Syndrome in Suriname; Clinical Presentation and Identification of Preceding Infections

Guillain-Barré syndrome (GBS) is associated with various types of preceding infections including Campylobacter jejuni and cytomegalovirus, but there is also an association with arthropod borne viruses (arboviruses), such as Zika virus, that are endemic in tropical regions. Here we present the clinical characteristics of 12 GBS patients from Suriname that were hospitalized between the beginning of 2016 and half 2018. Extensive diagnostic testing was performed for pathogens that are commonly associated with GBS, but also for arboviruses, in order to identify the preceding infection that might have led to GBS. With this extensive testing algorithm, we could identify a recent infection in six patients of which four of them had evidence of a recent Zika virus or dengue virus infection. These results suggest that arboviruses, specifically Zika virus but possibly also dengue virus, might be important causative agents of GBS in Suriname. Furthermore, we found that more accessibility of intravenous immunoglobulins or plasma exchange could improve the treatment of GBS in Suriname.

Recombinant Epstein-Barr virus glycoprotein 350 as a serological antigen

Epstein-Barr virus (EBV) glycoprotein 350 (gp350) is the most abundant glycoprotein expressed on the EBV envelope, the major target for neutralizing antibodies and also essential for virion attachment to B lymphocytes. Several studies have addressed EBV gp350 as a vaccine candidate, but less commonly as a potential antigen for serological assays. The aim of the current study was to develop a diagnostic tool to quantify EBV gp350-specific IgG in previously EBV-infected individuals. A construct encoding the extracellular domain of EBV gp350 (amino acid (aa) 1-860) was developed for expression in Chinese hamster ovary cells. Serum samples (n = 360) with known IgG serostatus against viral capsid antigen (VCA) and Epstein-Barr nuclear antigen 1 (EBNA1) were divided into three groups based on the differences in their serostatus: VCA + EBNA1+ (n = 120), VCA + EBNA1- (n = 120) and VCA-EBNA1- (n = 120). The samples were analyzed by indirect ELISA using recombinant EBV gp350 aa 1-860 as antigen. A clear majority, 108 of the 120 VCA + EBNA1+ samples, had detectable EBV gp350-specific IgG. Of the 120 VCA + EBNA1- samples, 79 had detectable EBV gp350-specific IgG. Only 2 of the 120 VCA-EBNA1- samples had detectable EBV gp350-specific IgG. The results reported here show that use of the EBV gp350 aa 1-860 ELISA can serve as a sensitive method for EBV-specific IgG detection in serum samples.

Recent Advances in Diagnostic Approaches for Epstein-Barr Virus

Epstein-Barr virus (EBV) is the causative agent of many diseases including infectious mononucleosis (IM), and it is associated with different subtypes of lymphoma, sarcoma and carcinoma such as Hodgkin's lymphoma, non-Hodgkin's lymphoma, nasopharyngeal carcinoma, and gastric carcinoma. With the advent of improved laboratory tests for EBV, a timelier and accurate diagnosis could be made to aid better prognosis and effective treatment. For histopathological lesions, the in situ hybridization (ISH) of EBV-encoded RNA (EBER) in biopsy tissues remains the gold standard for detecting EBV. Methods such as the heterophile antibody test, immunofluorescence assays, enzyme immunoassays, Western blot, and polymerase chain reaction (PCR) are also employed in the detection of EBV in different types of samples. The determination of EBV viral load using PCR, however, is gaining more prominence in the diagnosis of EBV-associated diseases. Given the challenge of false positive/negative results that are sometimes experienced during the detection of EBV, variability in results from different laboratories, and the impact of factors such as sample type and the immunological status of patients from whom samples are collected, the need to critically examine these present methods is invaluable. This review thus presents current advances in the detection of EBV, detailing the advantages and disadvantages of the various techniques. In addition, fundamental virological concepts are highlighted to enhance the greater understanding, the proper application, and the interpretation of EBV tests.

Evaluation of the antibody response to the EBV proteome in EBV-associated classical Hodgkin lymphoma

The humoral immune response to Epstein-Barr virus (EBV) in classical Hodgkin lymphoma (cHL) stratified by EBV tumor status is unclear. We examined IgG and IgA antibody responses against 202 protein sequences representing 86 EBV proteins using a microarray and sera from 139 EBV-positive cHL cases, 70 EBV-negative cHL cases and 141 population-based controls frequency matched to EBV-positive cHL cases on sex and age by area (UK, Denmark and Sweden). We leveraged existing data on the proportion of circulating B-cells infected by EBV and levels of serum CCL17, a chemokine secreted by cHL tumor cells, from a subset of the cHL cases in the UK. Total IgG but not IgA response level was significantly different between EBV-positive cHL cases and controls. The distinct serological response included significant elevations in 16 IgG antibodies and 2 IgA antibodies, with odds ratios_{highest vs. lowest tertile > 3} observed for the following EBV proteins: LMP1 (oncogene), BcLF1 (VCAp160, two variants) and BBLF1 (two variants). Our cHL IgG signature correlated with the proportion of circulating EBV-infected B-cells, but not serum CCL17 levels. We observed no differences in the anti-EBV antibody profile between EBV-negative cHL cases and controls. BdRF1(VCAp40)-IgG and BZLF1(Zta)-IgG were identified as the serological markers best able to distinguish EBV-positive from EBV-negative cHL tumors. Our results support the hypothesis that differences in the EBV antibody profile are specific to patients with EBV-positive cHL and are not universally observed as part of a systematically dysregulated immune response present in all cHL cases.

Anti-C1q Antibodies as Occurring in Systemic Lupus Erythematosus Could Be Induced by an Epstein-Barr Virus-Derived Antigenic Site

Previous infection with Epstein-Barr virus (EBV) is believed to trigger autoimmunity and to drive autoantibody generation as occurring in patients with systemic lupus erythematosus (SLE). Complement C1q and autoantibodies targeting it (anti-C1q) are also considered to be involved in the pathogenesis of SLE, independently of the impact of environmental insults. Still, the circumstances under which these autoantibodies arise remain elusive. By studying a major antigenic site of C1q targeted by anti-C1q (A08), we aimed to determine environmental factors and possible mechanisms leading to the development of anti-C1q. First, we determined antigenic residues of A08 that were critical for the binding of anti-C1q; importantly, we found the binding to depend on amino-acid-identity. Anti-C1q of SLE patients targeting these critical antigenic residues specifically cross-reacted with the EBV-related EBNA-1 (Epstein-Barr virus nuclear antigen 1)-derived peptide EBNA348. In a cohort of 180 SLE patients we confirmed that patients that were seropositive for EBV and recognized the EBNA348 peptide had increased levels of anti-A08 and anti-C1q, respectively. The correlation of anti-EBNA348 with anti-A08 levels was stronger in SLE patients than in matched healthy controls. Finally, EBNA348 peptide-immunization of C1q^−/− mice induced the generation of cross-reactive antibodies which recognized both the A08 epitope of C1q and intact C1q. These findings suggest that anti-C1q in SLE patients could be induced by an EBV-derived epitope through molecular mimicry, thereby further supporting the pathogenic role of EBV in the development of SLE. Considering the role of C1q and anti-C1q, modifying the anti-EBV response might be a promising strategy to improve the course of the disease.

The T-cell Response to Epstein-Barr Virus-New Tricks From an Old Dog

Epstein-Barr virus (EBV) infects most people and establishes life-long infection controlled by the host's immune system. The genetic stability of the virus, deep understanding of the viral antigens and immune epitopes recognized by the host's T-cell system and the fact that recent infection can be identified by the development of symptomatic infectious mononucleosis makes EBV a powerful system in which to study human immunology. The association between EBV and multiple cancers also means that the lessons learned have strong translational potential. Increasing evidence of a role for resident memory T-cells and non-conventional γδ T-cells in controlling EBV infection suggests new opportunities for research and means the virus will continue to provide exciting new insights into human biology and immunology into the future.

Antibodies to Human Herpesviruses in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients

Myalgic encephalomyelitis, also referred to as chronic fatigue syndrome (ME/CFS) is a debilitating disease characterized by myalgia and a sometimes severe limitation of physical activity and cognition. It is exacerbated by physical and mental activity. Its cause is unknown, but frequently starts with an infection. The eliciting infection (commonly infectious mononucleosis or an upper respiratory infection) can be more or less well diagnosed. Among the human herpesviruses (HHV-1-8), HHV-4 (Epstein-Barr virus; EBV), HHV-6 (including HHV-6A and HHV-6B), and HHV-7, have been implicated in the pathogenesis of ME/CFS. It was therefore logical to search for serological evidence of past herpesvirus infection/reactivation in several cohorts of ME/CFS patients (all diagnosed using the Canada criteria). Control samples were from Swedish blood donors. We used whole purified virus, recombinant proteins, and synthetic peptides as antigens in a suspension multiplex immunoassay (SMIA) for immunoglobulin G (IgG). The study on herpesviral peptides based on antigenicity with human sera yielded novel epitope information. Overall, IgG anti-herpes-viral reactivities of ME/CFS patients and controls did not show significant differences. However, the high precision and internally controlled format allowed us to observe minor relative differences between antibody reactivities of some herpesviral antigens in ME/CFS versus controls. ME/CFS samples reacted somewhat differently from controls with whole virus HHV-1 antigens and recombinant EBV EBNA6 and EA antigens. We conclude that ME/CFS samples had similar levels of IgG reactivity as blood donor samples with HHV-1-7 antigens. The subtle serological differences should not be over-interpreted, but they may indicate that the immune system of some ME/CFS patients interact with the ubiquitous herpesviruses in a way different from that of healthy controls.

Detection of EBV DNA in Non-Hodgkin Lymphoma Patients in Bulgaria

Epstein-Barr virus is the first human oncogenic virus associated with a broad range of different malignant diseases but its role in non-Hodgkin lymphomas (NHL) development still needs to be fully understood. High expression levels of EBV major genes are found in NHL tumor cells and free viral DNA circulates in the plasma of such individuals. In the current study we detected EBV DNA levels in plasma samples from NHL patients in order to validate its significance as a laboratory marker for disease monitoring. We investigated a cohort of 52 patients diagnosed with NHL in The University Hospital "St. Marina" Varna, Bulgaria. Viral DNA was extracted from single plasma samples using Kit Ribo Virus (Sacace Biotechnologies S.r.l., Como, Italy) and amplified with EBV Real-TM Quant (Sacace Biotechnologies S.r.l., Como, Italy). Plasma samples of the same patients were tested for presence of EBV VCA IgM/IgG antibodies with indirect ELISA tests (Euroimmun, Luebeck, Germany). We found 15.4% (95% CI 6.9-28.1%, n = 8) of the samples from NHL patients to be positive in quantitative PCR (range 674-221,333 copies/ml). The diffuse large B cell lymphomas and peripheral T cell lymphomas were most often associated (although not statistically significant, p = 0.167) with detectable plasma EBV DNA levels. To our knowledge, this is the first study about the role of EBV in NHL development in Bulgaria. The results we have obtained should stimulate new, larger investigations to apply the quantitative PCR technique in the routine laboratory EBV diagnosis.

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.

A study of Epstein-Barr virus infection in the Chinese tree shrew(Tupaia belangeri chinensis)

Background

Epstein–Barr virus (EBV) is closely associated with many human diseases, including a variety of deadly human malignant tumours. However, due to the lack of ideal animal models,the biological characteristics of EBV, particularly its function in tumourigenesis, have not been determined. Chinese tree shrews (Tupaia belangeri chinensis), which are similar to primates, have been used to establish a variety of animal models and have recently received much attention. Here, we established tree shrews as a model for EBV infection by intravenous injection.

Methods

Ten tree shrews were inoculated with EBV by intravenous injection,and blood was collected at regular intervals thereafter from the femoral artery or vein to detect EBV markers.

Results

Eight of 10 tree shrews showed evidence of EBV infection. In the 8 EBV-infected tree shrews, EBV copy number increased intermittently or transiently, EBV-related gene expression was detected, and anti-EBV antibodies increased to varying degrees. Macroscopic hepatomegaly was observed in 1 tree shrew, splenomegaly was observed in 4 tree shrews, and enlarged mesenteric lymph nodes were observed in 3 tree shrews. Haematoxylin and eosin (HE) staining showed splenic corpuscle hyperplasia in the spleens of 4 tree shrews and inflammatory cell infiltration of the liver of 1 tree shrew and of the mesenteric lymph nodes of 3 tree shrews. EBER in situ hybridization(ISH) and immunohistochemical (IHC) staining showed that EBER-, LMP1- and EBNA2- positive cells were present in the spleens and mesenteric lymph nodes of some tree shrews. Western blotting (WB) revealed EBNA1-positive cells in the spleens of 4 tree shrews. EBV markers were not detected by HE, EBER-ISH or IHC in the lung or nasopharynx.

Conclusions

These findings suggest that EBV can infect tree shrews via intravenous injection. The presented model offers some advantages for exploring the pathophysiology of EBV infection in humans.

Multiparametric Detection of Antibodies against Different EBV Antigens to Predict Risk for Nasopharyngeal Carcinoma in a High-Risk Population of China

In this study, we aimed to use the combined detection of multiple antibodies against Epstein-Barr virus (EBV) antigens to develop a model for screening and diagnosis of nasopharyngeal carcinoma (NPC). Samples of 300 nasopharyngeal carcinoma patients and 494 controls, including 294 healthy subjects (HC), 99 non-nasopharyngeal carcinoma cancer patients (NNPC), and 101 patients with benign nasopharyngeal lesions (BNL), were incubated with the EUROLINE Anti-EBV Profile 2, and band intensities were used to establish a risk prediction model. The nasopharyngeal carcinoma risk probability analysis based on the panel of VCAgp125 IgA, EBNA-1 IgA, EA-D IgA, EBNA-1 IgG, EAD IgG, and VCAp19 IgG displayed the best performance. When using 26.1% as the cutoff point in ROC analysis, the AUC value and sensitivity/specificity were 0.951 and 90.7%/86.2%, respectively, in nasopharyngeal carcinoma and all controls. In nasopharyngeal carcinoma and controls without the non-nasopharyngeal carcinoma and BNL groups, the AUC value and sensitivity/specificity were 0.957 and 90.7%/88.1%, respectively. The diagnostic specificity and sensitivity of the EUROLINE Anti-EBV Profile 2 assay for both nasopharyngeal carcinoma and early-stage nasopharyngeal carcinoma were higher than that of mono-antibody detection by immune-enzymatic assay and real-time PCR (EBV DNA). In the VCA-IgA-negative group, 82.6% of nasopharyngeal carcinoma patients showed high probability for nasopharyngeal carcinoma, and the negative predictive value was 97.1%. In the VCA-IgA-positive group, 73.3% of healthy subjects showed low probability. The positive predictive value reached 98.2% in this group. The nasopharyngeal carcinoma risk probability value determined by the EUROLINE Anti-EBV Profile 2 might be a suitable tool for nasopharyngeal carcinoma screening. Cancer Prev Res; 10(9); 542-50. ©2017 AACR.

Serological profiling of the EBV immune response in Chronic Fatigue Syndrome using a peptide microarray

BACKGROUND

Epstein-Barr-Virus (EBV) plays an important role as trigger or cofactor for various autoimmune diseases. In a subset of patients with Chronic Fatigue Syndrome (CFS) disease starts with infectious mononucleosis as late primary EBV-infection, whereby altered levels of EBV-specific antibodies can be observed in another subset of patients.

METHODS

We performed a comprehensive mapping of the IgG response against EBV comparing 50 healthy controls with 92 CFS patients using a microarray platform. Patients with multiple sclerosis (MS), systemic lupus erythematosus (SLE) and cancer-related fatigue served as controls. 3054 overlapping peptides were synthesised as 15-mers from 14 different EBV proteins. Array data was validated by ELISA for selected peptides. Prevalence of EBV serotypes was determined by qPCR from throat washing samples.

RESULTS

EBV type 1 infections were found in patients and controls. EBV seroarray profiles between healthy controls and CFS were less divergent than that observed for MS or SLE. We found significantly enhanced IgG responses to several EBNA-6 peptides containing a repeat sequence in CFS patients compared to controls. EBNA-6 peptide IgG responses correlated well with EBNA-6 protein responses. The EBNA-6 repeat region showed sequence homologies to various human proteins.

CONCLUSION

Patients with CFS had a quite similar EBV IgG antibody response pattern as healthy controls. Enhanced IgG reactivity against an EBNA-6 repeat sequence and against EBNA-6 protein is found in CFS patients. Homologous sequences of various human proteins with this EBNA-6 repeat sequence might be potential targets for antigenic mimicry.

Designing an effective vaccine to prevent Epstein-Barr virus-associated diseases: challenges and opportunities

INTRODUCTION

Epstein-Barr virus (EBV) is a ubiquitous herpesvirus associated with a number of clinical manifestations. Primary EBV infection in young adolescents often manifests as acute infectious mononucleosis and latent infection is associated with multiple lymphoid and epithelial cancers and autoimmune disorders, particularly multiple sclerosis. Areas covered: Over the last decade, our understanding of pathogenesis and immune regulation of EBV-associated diseases has provided an important platform for the development of novel vaccine formulations. In this review, we discuss developmental strategies for prophylactic and therapeutic EBV vaccines which have been assessed in preclinical and clinical settings. Expert commentary: Major roadblocks in EBV vaccine development include no precise understanding of the clinical correlates of protection, uncertainty about adjuvant selection and the unavailability of appropriate animal models. Recent development of new EBV vaccine formulations provides exciting opportunities for the formal clinical assessment of novel formulations.

Association between human herpesvirus & human endogenous retrovirus and MS onset & progression

This review discusses the role of Epstein-Barr virus (EBV), human herpesvirus 6 (HHV6) and human endogenous retroviruses (HERVs) in the onset and progression of multiple sclerosis (MS). Although EBV has been established as one of the causal factors in MS onset, its role in MS progression is still uncertain. Moreover, interactions between EBV and other risk factor on MS development still need more investment. With less consistent evidence than EBV, HHV6 has also been implicated in the pathogenesis of MS; moreover, it showed a closer connection with the disease activity. Recent studies found that HERVs were associated with the development and progression of MS. Some antiviral treatments have shown promise for clinical interventions in the future. Future studies are yet needed to fully clarify the role of these agents in MS onset and disease course and the modes by which they realise these effects.

Kinetics of Epstein-Barr Virus (EBV) Neutralizing and Virus-Specific Antibodies after Primary Infection with EBV

Prospective studies of antibodies to multiple Epstein-Barr virus (EBV) proteins and EBV neutralizing antibodies in the same individuals before, during, and after primary EBV infection have not been reported. We studied antibody responses to EBV in college students who acquired primary EBV infection during prospective surveillance and correlated the kinetics of antibody response with the severity of disease. Neutralizing antibodies and enzyme-linked immunosorbent assay (ELISA) antibodies to gp350, the major target of neutralizing antibody, reached peak levels at medians of 179 and 333 days after the onset of symptoms of infectious mononucleosis, respectively. No clear correlation was found between the severity of the symptoms of infectious mononucleosis and the peak levels of antibody to individual viral proteins or to neutralizing antibody. In summary, we found that titers of neutralizing antibody and antibodies to multiple EBV proteins increase over many months after primary infection with EBV.

The epidemiology of multiple sclerosis: insights to a causal cascade

MS-pathogenesis involves both genetic-susceptibility and environmental determinants. Three (or more) sequential environmental-factors are implicated. The first acts near birth, the second acts during childhood/adolescence, and the third acts subsequently. Two candidate factors (vitamin D deficiency and Epstein-Barr viral infection) seem particularly well-suited to the first two environmental-events but other factors (e.g., obesity and smoking behavior) seem also to be involved in the causal scheme. MS-pathogenesis can be modeled by incorporating both the environmental and genetic-factors into a causal scheme, which can then help to explain some of the changes in MS-epidemiology (e.g., increasing disease-prevalence, changing sex-ratio, and regional-variations in monozygotic-twin-concordance-rates), which have been taking place recently. This model suggests that genetic-susceptibility is overwhelmingly the most important determinant of MS and that, at least, 92.5% of individuals (and likely much more) are, essentially, incapable of developing MS, regardless of their specific environmental-exposures. Nevertheless, the genetics is complex and the contribution of any specific gene to MS-susceptibility seems to be quite modest. Thus, even for the DRB1*1501 allele (the strongest known MS-susceptibility marker), most carriers are not in the genetically-susceptible group. Moreover, 45-50% of individuals with MS lack this allele entirely and some of the haplotypes that carry this allele don't also confer any disease-risk. Finally, because the prevalence of genetic-susceptibility seems to be so similar throughout North America and Europe, and despite the crucial importance of a person's genetic make-up to disease pathogenesis, it is the environmental-factors, which largely responsible for the observed regional variations in disease-characteristics. Thus, despite MS being more common in women, men are more likely to be genetically-susceptible. This apparent paradox seems to relate to the fact that women are much more responsive than men to the recent changes in environmental-exposure (whatever these have been). These gender-differences may help to explain changes in the sex-ratio and the increasing disease-prevalence, which have both been observed recently. The potential importance of these conclusions regarding the role of environment in MS-pathogenesis is that they open the door to the possibility of pursuing strategies for primary primary disease prevention in the future.

Serodiagnosis for tumor viruses

The known human tumor viruses include the DNA viruses Epstein-Barr virus (EBV), Kaposi sarcoma herpesvirus (KSHV), Merkel cell polyomavirus (MCPyV), human papillomavirus (HPV), and hepatitis B virus (BV). RNA tumor viruses include human T-cell lymphotrophic virus type 1 (HTLV-1) and hepatitis C virus (HCV). The serological identification of antigens/antibodies in serum is a rapidly progressing field with utility for both scientists and clinicians. Serology is useful for conducting seroepidemiology studies and to inform on the pathogenesis and host immune response to a particular viral agent. Clinically, serology is useful for diagnosing current or past infection and for aiding in clinical management decisions. Serology is useful for screening blood donations for infectious agents and for monitoring the outcome of vaccination against these viruses. Serodiagnosis of human tumor viruses has improved in recent years with increased specificity and sensitivity of the assays, as well as reductions in cost and the ability to assess multiple antibody/antigens in single assays. Serodiagnosis of tumor viruses plays an important role in our understanding of the prevalence and transmission of these viruses and ultimately in the ability to develop treatments/preventions for these globally important diseases.

The immunology of Epstein-Barr virus-induced disease

Epstein-Barr virus (EBV) is usually acquired silently early in life and carried thereafter as an asymptomatic infection of the B lymphoid system. However, many circumstances disturb the delicate EBV-host balance and cause the virus to display its pathogenic potential. Thus, primary infection in adolescence can manifest as infectious mononucleosis (IM), as a fatal illness that magnifies the immunopathology of IM in boys with the X-linked lymphoproliferative disease trait, and as a chronic active disease leading to life-threatening hemophagocytosis in rare cases of T or natural killer (NK) cell infection. Patients with primary immunodeficiencies affecting the NK and/or T cell systems, as well as immunosuppressed transplant recipients, handle EBV infections poorly, and many are at increased risk of virus-driven B-lymphoproliferative disease. By contrast, a range of other EBV-positive malignancies of lymphoid or epithelial origin arise in individuals with seemingly intact immune systems through mechanisms that remain to be understood.

Infectious mononucleosis

Infectious mononucleosis is a clinical entity characterized by pharyngitis, cervical lymph node enlargement, fatigue and fever, which results most often from a primary Epstein-Barr virus (EBV) infection. EBV, a lymphocrytovirus and a member of the γ-herpesvirus family, infects at least 90% of the population worldwide, the majority of whom have no recognizable illness. The virus is spread by intimate oral contact among adolescents, but how preadolescents acquire the virus is not known. During the incubation period of approximately 6 weeks, viral replication first occurs in the oropharynx followed by viremia as early as 2 weeks before onset of illness. The acute illness is marked by high viral loads in both the oral cavity and blood accompanied by the production of immunoglobulin M antibodies against EBV viral capsid antigen and an extraordinary expansion of CD8(+) T lymphocytes directed against EBV-infected B cells. During convalescence, CD8(+) T cells return to normal levels and antibodies develop against EBV nuclear antigen-1. A typical clinical picture in an adolescent or young adult with a positive heterophile test is usually sufficient to make the diagnosis of infectious mononucleosis, but heterophile antibodies are not specific and do not develop in some patients especially young children. EBV-specific antibody profiles are the best choice for staging EBV infection. In addition to causing acute illness, long-term consequences are linked to infectious mononucleosis, especially Hodgkin lymphoma and multiple sclerosis. There is no licensed vaccine for prevention and no specific approved treatment. Future research goals are development of an EBV vaccine, understanding the risk factors for severity of the acute illness and likelihood of developing cancer or autoimmune diseases, and discovering anti-EBV drugs to treat infectious mononucleosis and other EBV-spurred diseases.

Infectious Mononucleosis

Infectious mononucleosis is a clinical entity characterized by sore throat, cervical lymph node enlargement, fatigue, and fever most often seen in adolescents and young adults and lasting several weeks. It can be caused by a number of pathogens, but this chapter only discusses infectious mononucleosis due to primary Epstein-Barr virus (EBV) infection. EBV is a γ-herpesvirus that infects at least 90% of the population worldwide. The virus is spread by intimate oral contact among teenagers and young adults. How preadolescents acquire the virus is not known. A typical clinical picture with a positive heterophile test is usually sufficient to make the diagnosis, but heterophile antibodies are not specific and do not develop in some patients. EBV-specific antibody profiles are the best choice for staging EBV infection. In addition to causing acute illness, there can also be long-term consequences as the result of acquisition of the virus. Several EBV-related illnesses occur including certain cancers and autoimmune diseases, as well as complications of primary immunodeficiency in persons with the certain genetic mutations. A major obstacle to understanding these sequelae has been the lack of an efficient animal model for EBV infection, although progress in primate and mouse models has recently been made. Key future challenges are to develop protective vaccines and effective treatment regimens.

Epstein-Barr Virus-Specific Humoral Immune Responses in Health and Disease

Epstein-Barr virus (EBV) is widely distributed in the world and associated with a still increasing number of acute, chronic, malignant and autoimmune disease syndromes. Humoral immune responses to EBV have been studied for diagnostic, pathogenic and protective (vaccine) purposes. These studies use a range of methodologies, from cell-based immunofluorescence testing to antibody-diversity analysis using immunoblot and epitope analysis using recombinant or synthetic peptide-scanning. First, the individual EBV antigen complexes (VCA , MA, EA(D), EA(R) and EBNA) are defined at cellular and molecular levels, providing a historic overview. The characteristic antibody responses to these complexes in health and disease are described, and differences are highlighted by clinical examples. Options for EBV vaccination are briefly addressed. For a selected number of immunodominant proteins, in particular EBNA1, the interaction with human antibodies is further detailed at the epitope level, revealing interesting insights for structure, function and immunological aspects, not considered previously. Humoral immune responses against EBV-encoded tumour antigens LMP1, LMP2 and BARF1 are addressed, which provide novel options for targeted immunotherapy. Finally, some considerations on EBV-linked autoimmune diseases are given, and mechanisms of antigen mimicry are briefly discussed. Further analysis of humoral immune responses against EBV in health and disease in carefully selected patient cohorts will open new options for understanding pathogenesis of individual EBV-linked diseases and developing targeted diagnostic and therapeutic approaches.

EBV & HHV6 reactivation is infrequent and not associated with MS clinical course

BACKGROUND

Among the environmental factors associated with multiple sclerosis (MS) causation, some of the strongest associations are with Epstein-Barr virus (EBV), and to a lesser extent human herpesvirus 6 (HHV6). Associations with clinical course are less conclusive, however.

METHODS

We evaluated serum anti-EBV-EA-R IgG and anti-HHV6 IgM, and EBV and HHV6 viral load (VL) for their associations with relapse, disability, and progression in disability in a prospective cohort of 198 participants with clinically definite MS.

RESULTS

Anti-EBV-EA-R IgG was detected in 81.8% of cases at study entry, and titers remained essentially unchanged during the study. Anti-HHV6 IgM was detected in only one participant, and EBV-VL (29%) and HHV6-VL (1.8%) were detected in a minority of samples, and where detected levels were low. Our previously demonstrated association between anti-HHV6 IgG and relapse hazard was not affected by adjustment for parameters of reactivation. We found no evidence that any of the viral markers were associated with disability or progression in disability. In relation to relapse, only EBV-VL was positively associated, although this was strongly influenced by a single individual.

CONCLUSION

Using a prospective cohort design, we found no convincing evidence that reactivation parameters of EBV or HHV6 were associated with subsequent MS relapse hazard or progression in disability, confirming previous findings, and indicating that herpesvirus reactivation is not an important driver of relapse or disability in this established MS population.

Epstein-Barr virus antibodies and the risk of associated malignancies: review of the literature

Epstein-Barr virus (EBV), a ubiquitous herpes virus that infects 90% of humans by adulthood, is linked to the development of various cancers, including nasopharyngeal carcinoma, gastric cancer, Burkitt lymphoma, non-Hodgkin lymphoma (NHL), and Hodgkin lymphoma. We reviewed the literature published since 1980 regarding an association between antibodies against EBV proteins and the risk of EBV-associated malignancies. Immunoglobulin A antibody levels that are elevated before diagnosis have consistently been associated with the risk of nasopharyngeal carcinoma, and patients with Hodgkin lymphoma have significantly higher immunoglobulin G antibody levels than disease-free controls. However, the link between the immune response to EBV and other EBV-associated malignancies was less clear. Although evidence of an association between the risk of Burkitt lymphoma and immunoglobulin G antibodies was consistent for available studies, the sample sizes were limited. Evidence for a link between antibodies against EBV and risk of either gastric cancer or NHL was inconsistent. Future investigations should account for tumor EBV status because only 7%-10% of gastric tumors and select NHL subtypes are related to EBV infection. Comparing differences in the associations between the humoral immune response to EBV and disease risk across cancers may help elucidate how this ubiquitous virus contributes to distinct tumors globally.

The epidemiology of multiple sclerosis: insights to disease pathogenesis

The purpose of studying the epidemiology of multiple sclerosis (MS) is twofold. First, it is important to understand clearly the natural history of the illness in order to assist patients in making decisions about their future with respect to issues such as family planning, the importance of securing lifelong healthcare, their ability to get and maintain employment, and making appropriate choices of therapy for their particular circumstances. This is not to suggest that, even with the best possible information, the ultimate prognosis for any individual can be predicted with absolute accuracy. It cannot. Nevertheless, accurate information can be very helpful both to reassure patients that many individuals with MS do remarkably well in the long term (perhaps, especially, with current and future therapies) and also to empower individuals with respect to their ability to make their own life choices. Second, and arguably the more important purpose for studying the epidemiology of MS, is to gain insights to the underlying causes of the disease. Indeed, if the principal mechanisms of disease pathogenesis were to be understood clearly, then it might be possible to entertain notions of either a cure for existing disease or the primary prevention of future disease. Much of our current understanding of disease pathogenesis, as discussed in other chapters of this volume, has been derived from basic science investigations of animal models of MS such as experimental autoimmune encephalomyelitis (EAE), and these models have provided considerable insight both to the complexity of the mammalian immune system and to the mechanisms underlying its dysfunction in inflammatory autoimmune conditions. Nevertheless, MS is a disease of humans without any known, naturally occurring, counterpart in any nonhuman species. For this reason, the clues to disease pathogenesis provided by a study of basic epidemiologic facts regarding MS (and by a systematic consideration of their implications) are essential to a comprehensive understanding of the human illness we call MS.

Performance of the architect EBV antibody panel for determination of Epstein-Barr virus infection stage in immunocompetent adolescents and young adults with clinical suspicion of infectious mononucleosis

The Architect EBV antibody panel is a new chemiluminescence immunoassay system used to determine the stage of Epstein-Barr virus (EBV) infection based on the detection of IgM and IgG antibodies to viral capsid antigen (VCA) and IgG antibodies against Epstein-Barr nuclear antigen 1 (EBNA-1). We evaluated its diagnostic accuracy in immunocompetent adolescents and young adults with clinical suspicion of infectious mononucleosis (IM) using the RecomLine EBV IgM and IgG immunoblots as the reference standard. In addition, the use of the antibody panel in a sequential testing algorithm based on initial EBNA-1 IgG analysis was assessed for cost-effectiveness. Finally, we investigated the degree of cross-reactivity of the VCA IgM marker during other primary viral infections that may present with an EBV IM-like picture. High sensitivity (98.3% [95% confidence interval {CI}, 90.7 to 99.7%]) and specificity (94.2% [95% CI, 87.9 to 97.8%]) were found after testing 162 precharacterized archived serum samples. There was perfect agreement between the use of the antibody panel in sequential and parallel testing algorithms, but substantial cost savings (23%) were obtained with the sequential strategy. A high rate of reactive VCA IgM results was found in primary cytomegalovirus (CMV) infections (60.7%). In summary, the Architect EBV antibody panel performs satisfactorily in the investigation of EBV IM in immunocompetent adolescents and young adults, and the application of an EBNA-1 IgG-based sequential testing algorithm is cost-effective in this diagnostic setting. Concomitant testing for CMV is strongly recommended to aid in the interpretation of EBV serological patterns.

Cellular immune controls over Epstein-Barr virus infection: new lessons from the clinic and the laboratory

Epstein-Barr virus (EBV), a human herpesvirus with potent B cell growth transforming ability, induces multiple cellular immune responses in the infected host. How these host responses work together to prevent virus pathogenicity, and how immune imbalance predisposes to disease, remain poorly understood. Here, we describe three ongoing lines of enquiry that are shedding new light on these issues. These focus on: (i) patients with infectious mononucleosis or its fatal equivalent, X-linked lymphoproliferative disease; (ii) EBV infection in a range of new, genetically defined, primary immune deficiency states; and (iii) experimental infection in two complementary animal models, the rhesus macaque and the human haemopoietic stem cell reconstituted mouse.

Deficient EBV-specific B- and T-cell response in patients with chronic fatigue syndrome

Epstein-Barr virus (EBV) has long been discussed as a possible cause or trigger of Chronic Fatigue Syndrome (CFS). In a subset of patients the disease starts with infectious mononucleosis and both enhanced and diminished EBV-specific antibody titers have been reported. In this study, we comprehensively analyzed the EBV-specific memory B- and T-cell response in patients with CFS. While we observed no difference in viral capsid antigen (VCA)-IgG antibodies, EBV nuclear antigen (EBNA)-IgG titers were low or absent in 10% of CFS patients. Remarkably, when analyzing the EBV-specific memory B-cell reservoir in vitro a diminished or absent number of EBNA-1- and VCA-antibody secreting cells was found in up to 76% of patients. Moreover, the ex vivo EBV-induced secretion of TNF-α and IFN-γ was significantly lower in patients. Multicolor flow cytometry revealed that the frequencies of EBNA-1-specific triple TNF-α/IFN-γ/IL-2 producing CD4(+) and CD8(+) T-cell subsets were significantly diminished whereas no difference could be detected for HCMV-specific T-cell responses. When comparing EBV load in blood immune cells, we found more frequently EBER-DNA but not BZLF-1 RNA in CFS patients compared to healthy controls suggesting more frequent latent replication. Taken together, our findings give evidence for a deficient EBV-specific B- and T-cell memory response in CFS patients and suggest an impaired ability to control early steps of EBV reactivation. In addition the diminished EBV response might be suitable to develop diagnostic marker in CFS.

MHC II tetramers visualize human CD4+ T cell responses to Epstein-Barr virus infection and demonstrate atypical kinetics of the nuclear antigen EBNA1 response

Characterization of the human EBV-specific CD4⁺ T cell response using MHC II tetramers reveals the latent EBV antigen response is more frequent than the lytic response with a delayed EBNA1 response that coincides with diminished cross-presentation.

Virus-specific CD4⁺ T cells are key orchestrators of host responses to viral infection yet, compared with their CD8⁺ T cell counterparts, remain poorly characterized at the single cell level. Here we use nine MHC II–epitope peptide tetramers to visualize human CD4⁺ T cell responses to Epstein–Barr virus (EBV), the causative agent of infectious mononucleosis (IM), a disease associated with large virus-specific CD8⁺ T cell responses. We find that, while not approaching virus-specific CD8⁺ T cell expansions in magnitude, activated CD4⁺ T cells specific for epitopes in the latent antigen EBNA2 and four lytic cycle antigens are detected at high frequencies in acute IM blood. They then fall rapidly to values typical of life-long virus carriage where most tetramer-positive cells display conventional memory markers but some, unexpectedly, revert to a naive-like phenotype. In contrast CD4⁺ T cell responses to EBNA1 epitopes are greatly delayed in IM patients, in line with the well-known but hitherto unexplained delay in EBNA1 IgG antibody responses. We present evidence from an in vitro system that may explain these unusual kinetics. Unlike other EBNAs and lytic cycle proteins, EBNA1 is not naturally released from EBV-infected cells as a source of antigen for CD4⁺ T cell priming.

Atypical prediagnosis Epstein-Barr virus serology restricted to EBV-positive Hodgkin lymphoma

An altered anti-Epstein-Barr virus (EBV) serologic profile preceding diagnosis is associated with an increased risk of Hodgkin lymphoma. It is unknown whether this atypical pattern predicts Hodgkin lymphoma risk further subdivided by determination of EBV in tumor cells. A nested case-control study of 128 incident Hodgkin lymphoma cases and 368 matched controls from active-duty military personnel with archived serum in the US Department of Defense Serum Repository was conducted to determine whether a panel of anti-EBV antibody titers differed in EBV(+) and EBV(-) Hodgkin lymphoma. Among 40 EBV(+) Hodgkin lymphoma cases and matched controls, statistically significant increased risks were associated with elevated anti-EBV VCA IgG antibody titers (relative risk = 3.1; 95% confidence interval [CI], 1.1-8.7), and an anti-EBNA-1/anti-EBNA-2 antibody ratio ≤ 1.0 versus > 1.0 (relative risk = 4.7; 95% CI, 1.6-13.8). In contrast, no significant associations were found among 88 EBV(-) Hodgkin lymphoma cases relative to their matched controls. In case-case analysis, EBV(+) disease was significantly associated with a low anti-EBNA-1/anti-EBNA-2 antibody ratio. This distinctive serologic response to EBV latent antigens, indicative of immune dysfunction in other clinical settings, is associated with an increased risk of developing EBV(+) but not EBV(-) Hodgkin lymphoma.

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.

Deciphering the role of Epstein-Barr virus in the pathogenesis of T and NK cell lymphoproliferations

Epstein-Barr virus (EBV) is a highly successful herpesvirus, colonizing more than 90% of the adult human population worldwide, although it is also associated with various malignant diseases. Primary infection is usually clinically silent, and subsequent establishment of latency in the memory B lymphocyte compartment allows persistence of the virus in the infected host for life. EBV is so markedly B-lymphotropic when exposed to human lymphocytes in vitro that the association of EBV with rare but distinct types of T and NK cell lymphoproliferations was quite unexpected. Whilst relatively rare, these EBV-associated T and NK lymphoproliferations can be therapeutically challenging and prognosis for the majority of patients is dismal. In this review, we summarize the current knowledge on the role of EBV in the pathogenesis of these tumours, and the implications for treatment.

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.

The viral load of Epstein-Barr virus (EBV) DNA in peripheral blood predicts for biological and clinical characteristics in Hodgkin lymphoma

PURPOSE

The Epstein-Barr virus (EBV) is present in the malignant Hodgkin/Reed-Sternberg (HRS) cells of 20% to 40% cases of Hodgkin lymphoma (HL) in Western countries. We were interested in the detection and quantification of cell-free plasma EBV-DNA as an indicator of biological and clinical characteristics in EBV-associated HL.

EXPERIMENTAL DESIGN

EBV was detected in peripheral blood compartments (whole blood, plasma, and mononuclear cells) at diagnosis by real-time PCR for the EBNA (EB nuclear antigen) region (n = 93) and in HRS cells by in situ hybridization for EBV-encoded small RNAs (EBER; n = 63). These data were correlated to histological and clinical characteristics, EBV serology, circulating cell-free DNA, and interleukin (IL)-6 levels.

RESULTS

Detection of EBV-DNA in plasma had a high specificity (90%), but a relatively low sensitivity (65%) to predict for EBV association. The viral load was higher in patients with advanced stage disease, older age in the presence of B-symptoms, and international prognostic score more than 2. The presence of EBV in HRS cells and higher plasma EBV-DNA copy numbers correlated to an increased frequency of tumor-infiltrating CD68+ macrophages in lymph node biopsies. Plasma EBV-DNA load correlated to circulating cell-free DNA and IL-6 levels, and inversely correlated to lymphocyte counts and EBNA1 antibody titers.

CONCLUSION

Although the presence of EBV-DNA in peripheral blood cannot be regarded as a surrogate marker for EBER, the plasma EBV-DNA load at HL diagnosis is an indicator of disease activity and biological characteristics associated with negative prognosis. Moreover, the inverse correlation to EBNA1 antibody titers and lymphocyte counts may indicate a reduction in immunosurveillance, favoring the expansion of EBV-HRS cells in HL.

A prospective study of Epstein-Barr virus antibodies and risk of non-Hodgkin lymphoma

Severe immunosuppression is an established risk factor for non-Hodgkin lymphoma (NHL), but an association with subclinical immune dysfunction is unclear. We conducted a case-control study nested in the Physicians' Health Study and the Nurses' Health Study cohorts to determine whether patterns of antibody response to Epstein-Barr virus (EBV) were associated with NHL risk. We measured antibody titers against viral capsid antigen, early antigen, and Epstein-Barr nuclear antigen (EBNA-1 and EBNA-2) in blood samples collected before diagnosis from 340 cases and 662 matched controls. Using conditional logistic regression, we estimated rate ratios (RRs) and 95% confidence intervals (CIs) for elevated versus normal titers and the ratio of anti-EBNA-1 to anti-EBNA-2 titers (≤ 1.0 vs > 1.0). We found no association between EBV serostatus, elevated titers, or an EBNA-1/EBNA-2 ratio ≤ 1.0 and NHL risk overall. For chronic lymphocytic leukemia/small lymphocytic lymphoma, suggestive associations were noted for elevated anti-EBNA-2 (RR, 1.74; 95% CI, 0.99-3.05), anti-viral capsid antigen (RR, 1.58; 95% CI, 0.79-3.14), and EBNA-1/EBNA-2 ratio ≤ 1.0 (RR, 1.52; 95% CI, 0.91-2.55). There was no evidence of heterogeneity by subtype. Overall, we found no evidence that EBV antibody profile predicts NHL risk in immunocompetent persons, with the possible exception of chronic lymphocytic leukemia/small lymphocytic lymphoma.

Epstein-Barr virus can infect rabbits by the intranasal or peroral route: an animal model for natural primary EBV infection in humans

Epstein-Barr virus (EBV) is spread universally in humans, and it causes infectious mononucleosis and sometimes induces serious EBV-associated disease. The detailed mechanism of primary infection in humans has remained unclear, because it is difficult to examine the dynamics of EBV in vivo. In this study, a natural EBV-infection rabbit model by intranasal or peroral inoculation is described. Ten male rabbits were examined for EBV-DNA or mRNA expression and anti-EBV antibodies in blood. Four of 10 rabbits showed the evidence of EBV infection; detection of EBV-DNA or EBV-related genes mRNA in peripheral blood mononuclear cells, increased EBV antibodies in the plasma, and the presence of lymphocytes expressing EBER1 and EBV-related gene proteins in the lymphoid tissues of a rabbit. Three of four infected rabbits were detected transiently EBV-DNA and/or mRNA of EBV-related genes such as EBNA1, EBNA2, BZLF1, and EA in blood, while in one of four, EBV-DNA and/or mRNA were detected for more than 200 days after viral inoculation. The level of EA-IgG increased and its level was maintained in all infected rabbits, whereas those of VCA-IgM and VCA-IgG increased transiently, and EBNA-IgG was not elevated. Pathological examination of a rabbit infected transiently revealed some scattered lymphocytes expressing EBER1, LMP1, and EBNA2 in the spleen and lymph nodes. EA expression was also observed in the spleen. These findings suggest that EBV can infect the rabbit by the intranasal or peroral route, and that this rabbit model is useful for examining the pathophysiology of natural primary EBV infection in humans.

Elevated Epstein-Barr virus-encoded nuclear antigen-1 immune responses predict conversion to multiple sclerosis

OBJECTIVE

The aims of the study were to determine the immune responses to candidate viral triggers of multiple sclerosis (MS) in patients with clinically isolated syndromes (CISs), and to evaluate their potential value in predicting conversion to MS.

METHODS

Immune responses to Epstein-Barr virus (EBV), human herpesvirus 6, cytomegalovirus (HCMV), and measles were determined in a cohort of 147 CIS patients with a mean follow-up of 7 years and compared with 50 demographically matched controls.

RESULTS

Compared with controls, CIS patients showed increased humoral (p < 0.0001) and cellular (p = 0.007) immune responses to the EBV-encoded nuclear antigen-1 (EBNA1), but not to other EBV-derived proteins. Immunoglobulin G (IgG) responses to other virus antigens and frequencies of T cells specific for HCMV and influenza virus gene products were unchanged in CIS patients. EBNA1 was the only viral antigen with which immune responses correlated with number of T2 lesions (p = 0.006) and number of Barkhof criteria (p=0.001) at baseline, and with number of T2 lesions (p = 0.012 at both 1 and 5 years), presence of new T2 lesions (p = 0.003 and p = 0.028 at 1 and 5 years), and Expanded Disability Status Scale score (p = 0.015 and p = 0.010 at 1 and 5 years) during follow-up. In a univariate Cox regression model, increased EBNA1-specific IgG responses predicted conversion to MS based on McDonald criteria (hazard ratio [95% confidence interval], 2.2 [1.2-4.3]; p = 0.003).

INTERPRETATION

Our results indicate that elevated immune responses toward EBNA1 are selectively increased in CIS patients and suggest that EBNA1-specific IgG titers could be used as a prognostic marker for disease conversion and disability progression.

Combined effects of smoking, anti-EBNA antibodies, and HLA-DRB1*1501 on multiple sclerosis risk

OBJECTIVE

To examine the interplay between smoking, serum antibody titers to the Epstein-Barr virus nuclear antigens (anti-EBNA), and HLA-DR15 on multiple sclerosis (MS) risk.

METHODS

Individual and pooled analyses were conducted among 442 cases and 865 controls from 3 MS case-control studies-a nested case-control study in the Nurses' Health Study/Nurses' Health Study II, the Tasmanian MS Study, and a Swedish MS Study. Conditional logistic regression models were used to calculate odds ratios (ORs) and 95% CIs for the association between smoking, anti-EBNA titers, HLA-DR15, and MS risk. Study estimates were pooled using inverse variance weights to determine a combined effect and p value.

RESULTS

Among MS cases, anti-EBNA titers were significantly higher in ever smokers compared to never smokers. The increased risk of MS associated with high anti-EBNA Ab titers was stronger among ever smokers (OR = 3.9, 95% CI = 2.7-5.7) compared to never smokers (OR = 1.8, 95% CI = 1.4-2.3; p for interaction = 0.001). The increased risk of MS associated with a history of smoking was no longer evident after adjustment for anti-EBNA Ab titers. No modification or confounding by HLA-DR15 was observed. The increased risk of MS associated with ever smoking was only observed among those who had high anti-EBNA titers (OR = 1.7, 95% CI = 1.1-2.6).

CONCLUSIONS

Smoking appears to enhance the association between high anti-EBNA titer and increased multiple sclerosis (MS) risk. The association between HLA-DR15 and MS risk is independent of smoking. Further work is necessary to elucidate possible biologic mechanisms to explain this finding.

Immunological fingerprinting method for differentiation of serum samples in research-oriented biobanks

An immunoenzymatic serum fingerprinting method was developed to establish a serum sample fingerprint based on IgG titers obtained with three different antigens. Three widely expressed antigens were selected for their capacity to induce long-lasting humoral immune responses. This fingerprinting method may be used to differentiate between two serum samples and to determine whether they come from the same primary blood specimen. The method showed a specificity of 99.5%. This method is suitable as a quality control method for biobanked serum samples.

Seroepidemiology of EBV and interpretation of the "isolated VCA IgG" pattern

The presence of VCA IgG in the absence of VCA IgM and EBNA-1 IgG antibodies makes classifying EBV infection more difficult as this serological picture can be seen in the case of past infection with EBNA-1 IgG loss or non-appearance, or acute infections with the early disappearance or delayed onset of VCA IgM. The aim of this study was to assess the prevalence of this pattern in 2,422 outpatients with suspected EBV infection examined in 2005-2006, and to interpret its significance by means of immunoblotting. One hundred and seventy-seven (7.3%) of the patients were VCA IgG-positive, VCA IgM-negative and EBNA-1 IgG-negative, 15 of whom (8.5%) presented with heterophile antibodies. Analysis by age class showed that the prevalence of isolated VCA IgG ranged from 4.5% in the subjects aged 1-10 years to 9% in those aged >60 years. Immunoblotting allowed 18.9% of the cases to be classified as acute and 81.1% as past infections, the latter being observed in about 37% of the patients aged less than 10 years and in 100% of those aged >30 years. Therefore, in our case series, the presence of isolated VCA IgG was associated usually with past infection, particularly among adults. In children aged less than 10 years, it was associated mainly with acute infection but as past infection may be present in about one-third of such children, this possibility should not be overlooked.

The causal cascade to multiple sclerosis: a model for MS pathogenesis

BACKGROUND

MS pathogenesis seems to involve both genetic susceptibility and environmental risk factors. Three sequential factors are implicated in the environmental risk. The first acts near birth, the second acts during childhood, and the third acts long thereafter. Two candidate factors (vitamin D deficiency and Epstein-Barr viral infection) seem well suited to the first two environmental events.

METHODOLOGY/PRINCIPAL FINDINGS

A mathematical Model for MS pathogenesis is developed, incorporating these environmental and genetic factors into a causal scheme that can explain some of the recent changes in MS-epidemiology (e.g., increasing disease prevalence, a changing sex-ratio, and regional variations in monozygotic twin concordance rates).

CONCLUSIONS/SIGNIFICANCE

This Model suggests that genetic susceptibility is overwhelmingly the most important determinant of MS pathogenesis. Indeed, over 99% of individuals seem genetically incapable of developing MS, regardless of what environmental exposures they experience. Nevertheless, the contribution of specific genes to MS-susceptibility seems only modest. Thus, despite HLA DRB1*1501 being the most consistently identified genetic marker of MS-susceptibility (being present in over 50% of northern MS patient populations), only about 1% of individuals with this allele are even genetically susceptible to getting MS. Moreover, because genetic susceptibility seems so similar throughout North America and Europe, environmental differences principally determine the regional variations in disease characteristics. Additionally, despite 75% of MS-patients being women, men are 60% more likely to be genetically-susceptible than women. Also, men develop MS at lower levels of environmental exposure than women. Nevertheless, women are more responsive to the recent changes in environmental-exposure (whatever these have been). This explains both the changing sex-ratio and the increasing disease prevalence (which has increased by a minimum of 32% in Canada over the past 35 years). As noted, environmental risk seems to result from three sequential components of environmental exposure. The potential importance of this Model for MS pathogenesis is that, if correct, a therapeutic strategy, designed to interrupt one or more of these sequential factors, has the potential to markedly reduce or eliminate disease prevalence in the future.

Population differences in immune marker profiles associated with human T-lymphotropic virus type I infection in Japan and Jamaica

The natural history of human T-lymphotropic virus type I (HTLV-I) has been shown to differ markedly by geographic area. The differences include contrasting patterns of risk of adult T-cell lymphoma (ATL) and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), which may be due in part to differences in host immune response to infection. To characterize variations in host immunity across populations, we compared serologic immune marker patterns in HTLV-I-endemic populations in Japan and Jamaica. We matched 204 participants with archived blood from the Miyazaki Cohort Study (Japan) and the Food Handlers Study (Jamaica)-i.e., 51 HTLV-I-positive ("carriers") and 51 HTLV-I-negative individuals ("noncarriers") from each population-by age, sex and blood collection year. We compared plasma concentrations of markers of T-cell-mediated (antigen-specific) and nonspecific immunity using regression models and correlation coefficients. Compared to Jamaican HTLV-I noncarriers, Japanese noncarriers had higher covariate-adjusted mean levels of T-cell activation markers, including antibody to Epstein-Barr virus nuclear antigen-1 (reciprocal titer 27 vs. 71, respectively, p=0.005), soluble interleukin-2 receptor-alpha (477 vs. 623 pg/mL, p=0.0008) and soluble CD30 (34 vs. 46 U/mL, p=0.0001) and lower levels of C-reactive protein (1.1 vs. 0.43 microg/mL, p=0.0004). HTLV-I infection was associated with activated T-cell immunity in Jamaicans but with diminished T-cell immunity in Japanese persons. The observed population differences in background and HTLV-I-related host immunity correspond closely to the divergent natural histories of infection observed among HTLV-I carriers in Japan and Jamaica and corroborate a role for host immune status in the contrasting patterns of ATL and HAM/TSP risk.