Evaluation of commercial EBV RecombLine assay for diagnosis of nasopharyngeal carcinoma

Serologic Profiling Using an Epstein-Barr Virus Mammalian Expression Library Identifies EBNA1 IgA as a Prediagnostic Marker for Nasopharyngeal Carcinoma

PURPOSE

The favorable prognosis of stage I and II nasopharyngeal carcinoma (NPC) has motivated a search for biomarkers for the early detection and risk assessment of Epstein-Barr virus (EBV)-associated NPC. Although EBV seropositivity is ubiquitous among adults, a spike in antibodies against select EBV proteins is a harbinger of NPC. A serologic survey would likely reveal which EBV antibodies could discriminate those at risk of developing NPC.

EXPERIMENTAL DESIGN

Lysates from a new EBV mammalian expression library were used in a denaturing multiplex immunoblot assay to survey antibodies against EBV in sera collected from healthy individuals who later developed NPC (incident cases) in a prospective cohort from Singapore and validated in an independent cohort from Shanghai, P.R. China.

RESULTS

We show that IgA against EBV nuclear antigen 1 (EBNA1) discriminated incident NPC cases from matched controls with 100% sensitivity and 100% specificity up to 4 years before diagnosis in both Singapore and Shanghai cohorts. Incident NPC cases had a greater IgG repertoire against lytic-classified EBV proteins, and the assortment of IgA against EBV proteins detected by the immunoblot assay increased closer to diagnosis.

CONCLUSIONS

Although NPC tumors consistently harbor latent EBV, the observed heightened systemic and mucosal immunity against lytic-classified antigens years prior to clinical diagnosis is consistent with enhanced lytic transcription. We conclude that an expanding EBV mucosal reservoir (which can be latent and/or lytic) is a risk factor for NPC. This presents an opportunity to identify those at risk of developing NPC using IgA against EBNA1 as a biomarker.

Deep Learning-Fuzzy Inference (DeLFI): An Interpretable Model for Detecting Indirect Immunofluorescence Patterns Associated with Nasopharyngeal Cancer

The detection of serum Epstein-Barr virus antibodies by immunofluorescence assay (IFA) is considered the gold standard screening test for nasopharyngeal cancer (NPC) in high-risk populations. Given the high survival rate after early detection in asymptomatic patients, compared to the poor prognosis in patients with late-stage NPC, screening using IFA has tremendous potential for saving lives in the general population. However, IFA requires visual interpretation of cellular staining patterns by trained pathology staff, making it labor intensive and hence nonscalable. In this study, an automated fuzzy inference (FI) system achieved high agreement with a human IFA expert in identifying cellular patterns associated with NPC (κ = 0.82). The integration of a deep-learning module into FI further improved the performance of FI (κ = 0.90) and reduced the number of uncertain cases that required manual evaluation. The performance of the resulting hybrid model, termed deep-learning FI (DeLFI), was then evaluated with a separate testing set of clinical samples. In this clinical validation, DeLFI outperformed human evaluation on the area under the curve (0.926 versus 0.821) and closely matched human performance on Youden J index (0.81 versus 0.80). It was concluded that the combination of deep learning with FI in DeLFI has the potential to improve the scalability and accuracy of NPC detection.

Accuracy Evaluation and Comparison of 14 Diagnostic Markers for Nasopharyngeal Carcinoma: A Meta-Analysis

The aim of the present study was to collect published studies and compare the diagnostic accuracy of different markers for nasopharyngeal carcinoma (NPC). We systematically searched PubMed/MEDLINE, EMBASE, Cochrane Library, CNKI, and Wanfang for relevant studies until April 29, 2020. The revised Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool was used to evaluate the methodological quality of the studies. The sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the curve (AUC) values of the diagnostic markers were combined by a bivariate mixed effect model to compare their diagnostic accuracy. We explored heterogeneity through meta-regression. In total, 244 records from 101 articles were included, with 49,432 total study subjects (13,109 cases and 36,323 controls). EA-IgG, Zta-IgG, and Epstein-Barr virus (EBV) DNA load in non-invasive nasopharyngeal brushings (EBV-DNA brushings) have both high sensitivity and specificity, EBNA1-IgG and VCA-IgG have only high sensitivity, and EBNA1-IgA, VCA-IgA, Rta-IgG, Zta-IgA, HSP70, and serum sialic acid (SA) have only high specificity. The bivariate mixed effect model of EA-IgA had a significant threshold effect. Meta-regression analysis showed that ethnicity affected EBNA1-IgA, EBNA1-IgG, VCA-IgA, and EBV DNA load in plasma, test methods affected EBNA1-IgG, publication year affected VCA-IgA, and sample size affected Rta-IgG. There was significant publication bias for VCA-IgA and Rta-IgG (P < 0.05). EA-IgG, Zta-IgG, and EBV-DNA brushings are good diagnostic markers for NPC. The diagnostic accuracy was influenced by publication year, sample size, test methods, and ethnicity.

From Anti-EBV Immune Responses to the EBV Diseasome via Cross-reactivity

Sequence analyses highlight a massive peptide sharing between immunoreactive Epstein-Barr virus (EBV) epitopes and human proteins that—when mutated, deficient or improperly functioning—associate with tumorigenesis, diabetes, lupus, multiple sclerosis, rheumatoid arthritis, and immunodeficiencies, among others. Peptide commonality appears to be the molecular platform capable of linking EBV infection to the vast EBV-associated diseasome via cross-reactivity and questions the hypothesis of the “negative selection” of self-reactive lymphocytes. Of utmost importance, this study warns that using entire antigens in anti-EBV immunotherapies can associate with autoimmune manifestations and further supports the concept of peptide uniqueness for designing safe and effective anti-EBV immunotherapies.

Tumor microenvironment contributes to Epstein-Barr virus anti-nuclear antigen-1 antibody production in nasopharyngeal carcinoma

Nuclear antigen-1 (NA1) protein of Epstein-Barr virus (EBV) is expressed in EBV-infected cells in the microenvironment of cancer. Since immune cells infiltrate abundantly in nasopharyngeal carcinoma (NPC) tumor tissues, we hypothesized that the local tumor microenvironment may perform an important role in the production of antibodies directed at NA1. Furthermore, we hypothesized that anti-NA1 antibody originating in the local microenvironment could be secreted into the saliva of patients with NPC. In the present study, 20 healthy controls and 39 patients with NPC treated with intensity-modulated radiation therapy were recruited for the study. Saliva and serum samples were collected from the NPC patients, and nasopharyngeal tissue samples from the patients with NPC. The titers of anti-NA1 antibody [immunoglobulin A (IgA)] were determined by ELISA. Expression of NA1, human leukocyte antigen-antigen D related (HLA-DR), cluster of differentiation (CD)80, CD86, CD3, CD4, CD19 and IgA was detected by immunohistochemical staining on paraffin-embedded nasopharyngeal tissue sections. Anti-NA1 antibodies were detected in the serum and saliva samples of the patients with NPC. In infiltrating cells, expression of HLA-DR, CD80, CD86, CD3, CD4, CD19 and IgA was detected, indicating that dendritic cells, T lymphocytes and B lymphocytes were all present in the local tumor tissues. Furthermore, expression of EBNA1 protein was detected on the membrane of the NPC tumor cells. Therefore, the NPC tumor microenvironment has the potential to initiate a humoral response to EBNA1 by producing IgA antibodies.

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.

EA-D p45-IgG as a potential biomarker for nasopharyngeal carcinoma diagnosis

AIM

To identify new biomarkers for NPC diagnosis with an anti-EBV Western blot test kit.

METHODS

Serum samples from 64 NPC patients and healthy subjects with four specific VCA-IgA/EA-IgA profiles were tested with an anti-EBV Western blot test kit from EUROIMMUN AG. Proteins were quantified with scores of intensity visually assigned to the protein bands. The markers which showed statistical differences between the NPC and non-NPC subjects were further evaluated in another 32 NPC patients and 32 controls in comparison with established biomarkers including VCA-IgA, EA-IgA, EBV-related protein IgG, and EBV DNA.

RESULTS

Among the markers screened, EA-D p45-IgG showed a statistically significant difference (p < 0.05) between NPC and non-NPC subjects with VCA-IgA positivy. In 32 VCA-IgA positive NPC patients and 32 control subjects, the diagnostic accuracy of EA-D p45-IgG was 78.1% with a positive predictive value of 77.8% and a negative predictive value of 78.6%. In the verification experiment, the specificity and sensitivity of EA-D p45-IgG were 75.0% and 90.6 %, respectively.

CONCLUSIONS

EA-D p45-IgG might be a potential biomarker for NPC diagnosis, especially among VCA-IgA positive subjects.

Generation and characterization of a novel recombinant antibody against LMP1-TES1 of Epstein-Barr virus isolated by phage display

Latent Membrane Protein 1 (LMP1) is a primary target for controlling tumorigenesis in Epstein-Barr virus related malignancies; in this study, we aimed to develop a specific antibody against the TES1 domain of the oncogenic LMP1. We screened a full human naïve Fab phage library against TES1 peptide, which consisted of C terminal-activating regions proximal 44 amino acids. After three rounds of panning, enrichment and testing by phage ELISA and further analyzed by DNA sequencing, we selected a phage clone with the highest affinity to LMP1-TES1 and designated it as htesFab. The positive clone was expressed in Escherichia coli and the purified htesFab was characterized for its binding specificity and affinity to LMP1. ELISA, immunofluorescence and FACS analysis confirmed that htesFab could recognize LMP1 TES1 both in vitro and in LMP1 expressing HNE2-LMP1 cells. Furthermore, MTT assay showed that htesFab inhibited the proliferation of HNE2-LMP1 cells in a dose-dependent manner. In summary, this study reported the isolation and characterization of human Fab, which specifically targets the C terminal region/TES1 of LMP1, and has potential to be developed as novel tool for the diagnosis and therapy of Epstein-Barr virus related carcinoma.

Longitudinal observation of Epstein-Barr virus antibodies in athletes during a competitive season

Epstein-Barr virus (EBV) serology continues to be the first diagnostic test when infectious mononucleosis is suspected. Due to possible mild immunosuppression in competitive athletes, EBV reactivation determined by increases in salivary viral load have been identified as one possible cause in recurrent respiratory infections. The long-term variation in EBV antibody levels in athletes compared to a control group remains unclear. The purpose of the study was to investigate the time course of changes in concentration of EBV antibodies in athletes with special emphasis on antibodies against early antigens (EAs) and avidity determination. During a competition season of approximately 12 months, the serological status of 15 biathletes (age 27 ± 3 years, 7 female, 8 male, international to Olympic level) was compared with 11 controls (age 23 ± 1 years; 1 female 10 male) at multiple time points. In addition, 43 healthy swimmers (age 22 ± 4 years, 18 female, 25 male, national to international level) were tested to validate the results with only two time points interspersed by approximately 6 months of intensive physical exercise. Analysis of quantitative antibody intensity bands revealed stable values during a competition season. In particular, IgG-antibodies against EAs may persist and were found in 15% of past infections in swimmers exhibiting fluctuations in concentration after 6 months. These results provide evidence that positive Anti-EA-IgG may persist in healthy athletes and thus, should not be used to diagnose EBV reactivations or to identify a compromised immune function.