Establishment of VCA and EBNA1 IgA-based combination by enzyme-linked immunosorbent assay as preferred screening method for nasopharyngeal carcinoma: a two-stage design with a preliminary performance study and a mass screening in southern China

Kinetics of EBV antibody-based NPC risk scores in Taiwan NPC multiplex families

Nasopharyngeal carcinoma (NPC) risk prediction models based on Epstein-Barr virus (EBV)-antibody testing have shown potential for screening of NPC; however, the long-term stability is unclear. Here, we investigated the kinetics of two EBV-antibody NPC risk scores within the Taiwan NPC Multiplex Family Study. Among 545 participants with multiple blood samples, we evaluated the stability of a 2-marker enzyme-linked immunosorbent assay score and 13-marker multiplex serology score using the intra-class correlation coefficient (ICC) by fitting a linear mixed model that accounted for the clustering effect of multiple measurements per subject and age. We also estimated the clustering of positive tests using Fleiss's kappa statistic. Over an average 20-year follow-up, the 2-marker score showed high stability over time, whereas the 13-marker score was more variable (p < .05). Case-control status is associated with the kinetics of the antibody response, with higher ICCs among cases. Positive tests were more likely to cluster within the same individual for the 2-marker score than the 13-marker score (p < .05). The 2-marker score had an increase in specificity from ~90% for single measurement to ~96% with repeat testing. The 13-marker score had a specificity of ~73% for a single measurement that increased to ~92% with repeat testing. Among individuals who developed NPC, none experienced score reversion. Our findings suggest that repeated testing could improve the specificity of NPC screening in high-risk NPC multiplex families. Further studies are required to determine the impact on sensitivity, establish optimal screening intervals, and generalize these findings to general population settings in high-risk regions.

The serological diagnostic value of EBV-related IgA antibody panels for nasopharyngeal carcinoma: a diagnostic test accuracy meta-analysis

BACKGROUND

Nasopharyngeal carcinoma (NPC) is diagnosed relatively late and has a poor prognosis, requiring early detection to reduce the disease burden. This diagnostic test accuracy meta-analysis evaluated the serological diagnostic value of nine EBV-related IgA antibody panels (EBNA1-IgA, VCA-IgA, EA-IgA, Zta-IgA, EBNA1-IgA + VCA-IgA, VCA-IgA + EA-IgA, VCA-IgA + Rta-IgG, EBNA1-IgA + VCA-IgA + Zta-IgA and VCA-IgA + EA-IgA + Rta-IgG), aiming to identify suitable serological detection biomarkers for NPC screening.

METHODS

PubMed, Embase, China National Knowledge Infrastructure and Chinese BioMedical Literature Database were searched from January 1st, 2000 to September 30th, 2023, with keywords nasopharyngeal carcinoma, IgA, screening, early detection, early diagnosis, sensitivity and specificity. Articles on the diagnostic value of serum EBV-related IgA antibody panels for NPC were included. Study selection, data extraction, and quality assessment were performed independently by two researchers, and a third researcher was consulted in the case of disagreement. Bivariate models were used for statistical analysis. The quality of included studies was evaluated through Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2).

RESULTS

A total of 70 articles were included, involving 11 863 NPC cases and 34 995 controls. Among the nine EBV-related IgA antibody panels, EBNA1-IgA + VCA-IgA [0.928 (0.898, 0.950)], VCA-IgA + Rta-IgG [0.925 (0.890, 0.949)], EBNA1-IgA + VCA-IgA + Zta-IgA [0.962 (0.909, 0.985)] and VCA-IgA + EA-IgA + Rta-IgG [0.945 (0.918, 0.964)] demonstrated higher pooled sensitivity (95%CI). In terms of diagnostic odds ratio (DOR) (95%CI), EBNA1-IgA + VCA-IgA [107.647 (61.173, 189.430)], VCA-IgA + Rta-IgG [105.988 (60.118, 186.857)] and EBNA1-IgA + VCA-IgA + Zta-IgA [344.450 (136.351, 870.153)] showed superior performance. Additionally, the SROC curves for EBNA1-IgA + VCA-IgA and VCA-IgA + Rta-IgG were more favorable. However, publication bias was detected for VCA-IgA (P = 0.005) and EBNA1-IgA + VCA-IgA (P = 0.042).

CONCLUSIONS

In general, parallel detection of serum EBNA1-IgA, VCA-IgA and Zta-IgA antibodies using ELISA demonstrates better pooled sensitivity and DOR among the studied panels. In the cases where fewer indicators are used, serum VCA-IgA and EBNA1-IgA/Rta-IgG antibody panel exhibits a comparable performance.

TRIAL REGISTRATION

The International Prospective Register of Systematic Reviews registration number: CRD42023426984, registered on May 28, 2023.

Detection of Epstein‒Barr virus DNA methylation as tumor markers of nasopharyngeal carcinoma patients in saliva, oropharyngeal swab, oral swab, and mouthwash

Saliva biopsy of nasopharyngeal carcinoma (NPC) has been developed in our latest study, indicating the application of oral sampling in NPC detection. Further exploration of the potential for self-sampling from the oral cavity is necessary. A total of 907 various samples from oral cavity, including saliva (n = 262), oropharyngeal swabs (n = 250), oral swabs (n = 210), and mouthwash (n = 185), were collected. Epstein‒Barr virus (EBV) DNA methylation at the 12,420 bp CpG site in EBV genome from the repeat-copy W promoter (Wp) region and at the 11,029 bp CpG site in the single-copy C promoter (Cp) region were simultaneously detected in these samples. A significant increase in EBV methylation, no matter at Wp or Cp region, was found in all types of samples from NPC patients. However, EBV DNA methylation in saliva and oropharyngeal swab showed a better diagnostic performance in detecting NPC. The combination of these two sample types and two markers could help to improve the detection of NPC. Our study further explored the optimal self-sampling methods and detection target in the detection of NPC and may facilitate the application of EBV DNA methylation detection in a home-based large-scale screening of NPC.

Clinical performance of a prefabricated immunofluorescence assay for nasopharyngeal cancer screening

BACKGROUND

Epstein-Barr virus (EBV) IgA serology for viral capsid antigen (VCA) and early antigen (EA) aids early detection of nasopharyngeal cancer (NPC), resulting in improved survival. We evaluated the diagnostic performance of a prefabricated immunofluorescent assay (IFA) for NPC screening in high-risk individuals.

METHODS

Sera from 96 biopsy-proven patients with NPC diagnosed at the outpatient clinic and 96 healthy family members were tested for EBV-VCA IgA and EBV-EA IgA using the prefabricated IFA from EUROIMMUN (EI) and the traditional immunofluorescence method.

RESULTS

The AUC of EI EBV-VCA IgA and EBV-EA IgA was 0.907 (95% confidence interval [CI]: 0.894-0.965) and 0.898 (95% CI: 0.848-0.947), respectively. Combined testing with the prefabricated assay at a threshold of VCA ≥1:320 or EA ≥1:10 showed 92.7% sensitivity and 81.2% specificity. Overall, the traditional EBV-EA IgA assay demonstrated the best accuracy (sensitivity 91.7% and specificity 96.9%) at a threshold of ≥1:5.

CONCLUSION

While the traditional IFA method was more accurate, the prefabricated IFA test kit can be a useful tool for NPC screening in high-risk populations.

Recent advances in early detection of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) arises from the mucosal epithelium of the nasopharynx and is frequently located in the pharyngeal crypts. This is a highly aggressive malignant tumor that frequently leads to distant metastases in many cases and poses a significant public health challenge, particularly in certain geographic regions globally. This review discusses the epidemiology, risk factors, diagnosis, and treatment options for NPC, emphasizing the importance of early detection and comprehensive management strategies in improving patient outcomes. Moreover, the article explores the intricate mechanisms that cause NPC. Comprehending these fundamental principles can assist in creating specific prevention and therapy approaches for NPC. Recent advances in diagnostic methods, including imaging tests and molecular biomarkers, are emphasized to improve early diagnosis and individualized treatment strategies for individuals with NPC. The review also explores the most recent advancements in treating early-stage (stage I and II) NPC patients, highlighting the changing landscape of individualized therapy approaches for this particular set of patients.

Multiplex assays reveal anti-EBV antibody profile and its implication in detection and diagnosis of nasopharyngeal carcinoma

Epstein-Barr virus (EBV) is detected in nearly 100% of nonkeratinizing nasopharyngeal carcinoma (NPC) and EBV-based biomarkers are used for NPC screening in endemic regions. Immunoglobulin A (IgA) against EBV nuclear antigen 1 (EBNA1) and viral capsid antigen (VCA), and recently identified anti-BNLF2b antibodies have been shown to be the most effective screening tool; however, the screening efficacy still needs to be improved. This study developed a multiplex serological assay by testing IgA and immunoglobulin G (IgG) antibodies against representative EBV antigens that are highly transcribed in NPC and/or function crucially in viral reactivation, including BALFs, BNLF2a/b, LF1, LF2, and Zta (BZLF1). Among them, BNLF2b-IgG had the best performance distinguishing NPC patients from controls (area under the curve: 0.951, 95% confidence interval [CI]: 0.913-0.990). Antibodies to lytic antigens BALF2 and VCA were significantly higher in advanced-stage than in early-stage tumors; in contrast, antibodies to latent protein EBNA1 and early lytic antigen BNLF2b were not correlated with tumor progression. Accordingly, a novel strategy combining EBNA1-IgA and BNLF2b-IgG was proposed and validated improving the integrated discrimination by 15.8% (95% CI: 9.8%-21.7%, p < .0001) compared with the two-antibody method. Furthermore, we found EBV antibody profile in patients was more complicated compared with that in healthy carriers, in which stronger correlations between antibodies against different phases of antigens were observed. Overall, our serological assay indicated that aberrant latent infection of EBV in nasopharyngeal epithelial cells was probably a key step in NPC initiation, while more lytic protein expression might be involved in NPC progression.

VLDL and LDL Subfractions Enhance the Risk Stratification of Individuals Who Underwent Epstein-Barr Virus-Based Screening for Nasopharyngeal Carcinoma: A Multicenter Cohort Study

Serological tests for Epstein-Barr virus (EBV) antibodies have been widely conducted for the screening of nasopharyngeal carcinoma (NPC) in endemic areas. Further risk stratification of NPC can be achieved through plasma lipoprotein and metabolic profiles. A total of 297 NPC patients and 149 EBV-positive participants are enrolled from the NCT03919552 and NCT05682703 cohorts for plasma nuclear magnetic resonance (NMR) metabolomic analysis. Small, dense very low density lipoprotein particles (VLDL-5) and large, buoyant low density lipoprotein particles (LDL-1) are found to be closely associated with nasopharyngeal carcinogenesis. Herein, an NMR-based risk score (NRS), which combines lipoprotein subfractions and metabolic biomarkers relevant to NPC, is developed and well validated within a multicenter cohort. Combining the median cutoff value of the NRS (N50) with that of the serological test for EBV antibodies, the risk stratification model achieves a satisfactory performance in which the area under the curve (AUC) is 0.841 (95% confidence interval: 0.811-0.871), and the positive predictive value (PPV) reaches 70.08% in the combined cohort. These findings not only suggest that VLDL-5 and LDL-1 particles can serve as novel risk factors for NPC but also indicate that the NRS has significant potential in personalized risk prediction for NPC.

Antibody Profiling of Pan-Cancer Viral Proteome Reveals Biomarkers for Nasopharyngeal Carcinoma Diagnosis and Prognosis

Diagnosing, predicting disease outcome, and identifying effective treatment targets for virus-related cancers are lacking. Protein biomarkers have the potential to bridge the gap between prevention and treatment for these types of cancers. While it has been shown that certain antibodies against EBV proteins could be used to detect nasopharyngeal carcinoma (NPC), antibodies targeting are solely a tiny part of the about 80 proteins expressed by the EBV genome. Furthermore, it remains unclear what role other viruses play in NPC since many diseases are the result of multiple viral infections. For the first time, this study measured both IgA and IgG antibody responses against 646 viral proteins from 23 viruses in patients with NPC and control subjects using nucleic acid programmable protein arrays. Candidate seromarkers were then validated by ELISA using 1665 serum samples from three clinical cohorts. We demonstrated that the levels of five candidate seromarkers (EBV-BLLF3-IgA, EBV-BLRF2-IgA, EBV-BLRF2-IgG, EBV-BDLF1-IgA, EBV-BDLF1-IgG) in NPC patients were significantly elevated than controls. Additional examination revealed that NPC could be successfully diagnosed by combining the clinical biomarker EBNA1-IgA with the five anti-EBV antibodies. The sensitivity of the six-antibody signature at 95% specificity to diagnose NPC was comparable to the current clinically-approved biomarker combination, VCA-IgA, and EBNA1-IgA. However, the recombinant antigens of the five antibodies are easier to produce and standardize compared to the native viral VCA proteins. This suggests the potential replacement of the traditional VCA-IgA assay with the 5-antibodies combination to screen and diagnose NPC. Additionally, we investigated the prognostic significance of these seromarkers titers in NPC. We showed that NPC patients with elevated BLLF3-IgA and BDLF1-IgA titers in their serum exhibited significantly poorer disease-free survival, suggesting the potential of these two seromarkers as prognostic indicators of NPC. These findings will help develop serological tests to detect and treat NPC in the future.

Host genetic variants, Epstein-Barr virus subtypes, and the risk of nasopharyngeal carcinoma: Assessment of interaction and mediation

Epstein-Barr virus (EBV) and human leukocyte antigen (HLA) polymorphisms are well-known risk factors for nasopharyngeal carcinoma (NPC). However, the combined effects between HLA and EBV on the risk of NPC are unknown. We applied a causal inference framework to disentangle interaction and mediation effects between two host HLA SNPs, rs2860580 and rs2894207, and EBV variant 163364 with a population-based case-control study in NPC-endemic southern China. We discovered the strong interaction effects between the high-risk EBV subtype and both HLA SNPs on NPC risk (rs2860580, relative excess risk due to interaction [RERI] = 4.08, 95% confidence interval [CI] = 2.03-6.14; rs2894207, RERI = 3.37, 95% CI = 1.59-5.15), accounting for the majority of genetic risk effects. These results indicate that HLA genes and the high-risk EBV have joint effects on NPC risk. Prevention strategies targeting the high-risk EBV subtype would largely reduce NPC risk associated with EBV and host genetic susceptibility.

Development and analytical validation of a novel nasopharynx swab-based Epstein-Barr virus C promoter methylation quantitative assay for nasopharyngeal carcinoma detection

OBJECTIVES

Epstein-Barr virus (EBV) C promoter (Cp) hypermethylation, a crucial factor for EBV latent infection of nasopharyngeal epithelial cells, has been recognized as a promising biomarker for nasopharyngeal carcinoma (NPC) detection. In this study, we develop a novel EBV Cp methylation quantification (E-CpMQ) assay and evaluate its diagnostic performance for NPC detection.

METHODS

A novel qPCR assay for simultaneous quantification of methylated- and unmethylated EBV Cp was developed by the combinational modification of MethyLight and QASM, with an innovative calibrator to improve the detection accuracy and consistency. The NP swab samples and synthetic standards were used for the analytical validation of the E-CpMQ. The diagnostic efficacy of the developed E-CpMQ assay was validated in 137 NPC patients and 137 non-NPC controls.

RESULTS

The E-CpMQ assay can detect the EBV Cp methylation ratio in one reaction system under 10 copies with 100 % recognition specificity, which is highly correlated to pyrosequencing with a correlation coefficient over 0.99. The calibrated E-CpMQ assay reduces the coefficient of variation by an average of 55.5 % with a total variance of less than 0.06 units standard deviation (SD). Linear methylation ratio detection range from 4.76 to 99.01 %. The sensitivity and specificity of the E-CpMQ respectively are 96.4 % (95 % CI: 91.7-98.8 %), 89.8 % (95 % CI: 83.5-94.3 %).

CONCLUSIONS

The developed E-CpMQ assay with a calibrator enables accurate and reproducible EBV Cp methylation ratio quantification and offers a sensitive, specific, cost-effective method for NPC early detection.

Serum Anti-Zta and Anti-LMP1 Antibodies in Oropharyngeal Cancer Related to Epstein-Barr Virus-Diagnostic Usefulness

BACKGROUND

The role of the Epstein-Barr virus (EBV), the first known human oncogenic virus, in the development of nasopharyngeal cancer (NPC) is already well documented. There are few studies in the available scientific literature on oropharyngeal cancer associated with EBV infection. Due to the lack of an effective vaccine against EBV, it is necessary to search for new markers for the early diagnosis and prognosis of this disease. The aim of current study was to determine the usefulness of anti-Zta and anti-LMP1 antibodies as diagnostic and prognostic markers in EBV positive OPSCC patients.

METHODS

For this purpose, experiments were carried out to determine both the prevalence and level of EBVCA, EBNA1, EA, Zta, and LMP1 antibodies in serum patients depending on histological differentiation-grading and TNM classification (ELISA assay).

RESULTS

Based on the obtained results, we showed that OPSCC EBV positive patients are characterized by a higher level of anti-Zta antibodies than in the EBV negative group. Their level depended on the clinical stage. Moreover, a ROC analysis confirmed the diagnostic accuracy of anti-Zta antibodies.

CONCLUSIONS

Anti-Zta and anti-LMP1 antibodies may be useful in the diagnosis of OPSCC. It seems that combined antibody testing should be performed to increase diagnostic accuracy.

Clinical significance of anti-Epstein-Barr virus antibodies in systemic chronic active Epstein-Barr virus disease

Systemic chronic active Epstein-Barr virus disease (sCAEBV) is a rare and fatal neoplasm, involving clonally proliferating Epstein-Barr virus (EBV)-infected T cells or natural killer cells. Patients with sCAEBV have abnormal titers of anti-EBV antibodies in their peripheral blood, but their significance is unknown. We retrospectively investigated titers and their relationship with the clinical features of sCAEBV using the data collected by the Japanese nationwide survey. Eighty-four patients with sCAEBV were analyzed. The anti-EBV nuclear antigen (EBNA) antibody, targeting EBNA-expressing EBV-positive cells, was found in 87.5% of children (<15 years old), 73.7% of adolescents and young adults (15-39 years old), and 100% of adults (≥40 years old). Anti-EBNA antibody titers were significantly lower and anti-VCA-IgG antibody titers significantly higher in patients with sCAEBV than those in healthy controls (p < 0.0001). Patients with high anti-VCA-IgG and anti-early antigen-IgG antibody (antibodies against the viral particles) levels had significantly better 3-year overall survival rates than those with low titers, suggesting that patients with sCAEBV have a reduced immune response to EBV-infected cells.

Early screening of nasopharyngeal carcinoma

The low positive predictive value (PPV) of early screening of nasopharyngeal carcinoma (NPC) is the problems that need to be solved urgently. The combination of cell-free DNA (cfDNA) methylation testing and Epstein-Barr virus (EBV) serological testing is the key to solve this problem. This paper reviews recent advances in early screening for NPC and cfDNA methylation, with future perspectives. Pubmed was searched for the literature related to early screening of NPC and cfDNA methylation in the past 5 years. The results of these studies were summarized. Despite these efforts, the PPV is still low (10%). Previous studies have shown that cfDNA methylation analysis has good specificity and accuracy across a variety of tumors. The combination of cfDNA methylation and EBV detection helps to improve the PPV for early screening of NPC. The combination of cfDNA methylation and EBV serological testing is key to addressing the low PPV of NPC early screening.

Performance and Operational Feasibility of Epstein-Barr Virus-Based Screening for Detection of Nasopharyngeal Carcinoma: Direct Comparison of Two Alternative Approaches

PURPOSE

Two Epstein-Barr virus (EBV)-based testing approaches have shown promise for early detection of nasopharyngeal carcinoma (NPC). Neither has been independently validated nor their performance compared. We compared their diagnostic performance in an independent population.

METHODS

We tested blood samples from 819 incident Taiwanese NPC cases (213 early-stage, American Joint Committee on Cancer version 7 stages I and II) diagnosed from 2010 to 2014 and from 1,768 controls from the same region, frequency matched to cases on age and sex. We compared an EBV antibody score using immunoglobulin A antibodies measured by enzyme-linked immunosorbent assay (EBV antibody score) and plasma EBV DNA load measured by real-time PCR followed by next-generation sequencing (NGS) among EBV DNA-positive individuals (EBV DNA algorithm).

RESULTS

EBV antibodies and DNA load were measured for 2,522 (802 cases; 1,720 controls) and 2,542 (797 cases; 1,745 controls) individuals, respectively. Of the 898 individuals positive for plasma EBV DNA and therefore eligible for NGS, we selected 442 (49%) for NGS testing. The EBV antibody score had a sensitivity of 88.4% (95% CI, 86.1 to 90.6) and a specificity of 94.9% (95% CI, 93.8 to 96.0) for NPC. The EBV DNA algorithm yielded significantly higher sensitivity (93.2%; 95% CI, 91.3 to 94.9; P = 1.33 × 10-4) and specificity (98.1%; 95% CI, 97.3 to 98.8; P = 3.53 × 10-7). For early-stage NPC, the sensitivities were 87.1% (95% CI, 82.7 to 92.4) for the EBV antibody score and 87.0% (95% CI, 81.9 to 91.5) for the EBV DNA algorithm (P = .514). For regions with a NPC incidence of 20-100/100,000 person-years (eg, residents in southern China and Hong Kong), these two approaches yielded similar numbers needed to screen (EBV antibody score: 5,656-1,131; EBV DNA algorithm: 5,365-1,073); positive predictive values ranged from 0.4% to 1.7% and 1.0% to 4.7%, respectively.

CONCLUSION

We demonstrated high sensitivity and specificity of EBV antibody and plasma EBV DNA for NPC detection, with slightly inferior performance of the EBV antibody score. Cost-effectiveness studies are needed to guide screening implementation.

Saliva biopsy: Detecting the difference of EBV DNA methylation in the diagnosis of nasopharyngeal carcinoma

Saliva sampling is a non-invasive method, and could be performed by donors themselves. However, there are few studies reporting biomarkers in saliva in the diagnosis of NPC. A total of 987 salivary samples were used in this study. First, EBV DNA methylation was profiled by capture sequencing in the discovery cohort (n = 36). Second, a q-PCR based method was developed and five representative EBV DNA CpG sites (11 029 bp, 45 849 bp, 57 945 bp, 66 226 bp and 128 102 bp) were selected and quantified to obtain the methylated density in the validation cohort1 (n = 801). Third, a validation cohort2 (n = 108) was used to further verify the differences of EBV methylation in saliva. A significant increase of EBV methylation was found in NPC patients compared with controls. The methylated score of EBV genome obtained by capture sequencing could distinguish NPC from controls (sensitivity 90%, specificity 100%). Further, the methylated density of EBV DNA CpG sites revealed by q-PCR showed a good diagnostic performance. The sensitivity and specificity of detecting a single CpG site (11 029 bp) could reach 75.4% and 99.7% in the validation cohort1, and 78.2% and 100% in the validation cohort2. Besides, the methylated density of the CpG site was found to decrease below the COV in NPC patients after therapy, and increase above the COV after recurrence. Our study provides an appealing alternative for the non-invasive detection of NPC without clinical setting. It paves the way for conducting a home-based large-scale screening in the future.

Combining Epstein-Barr virus antibodies for early detection of nasopharyngeal carcinoma: A meta-analysis

OBJECTIVE

Epstein-Barr virus-related antibody seromarkers including VCA-IgA, EA-IgA, EBNA1-IgA, and Rta-IgG are used as markers for the detection of nasopharyngeal carcinoma (NPC). This meta-analysis was conducted to evaluate the diagnostic performance of their use in combined assays.

METHODS

Computerized searching of five electronic databases, supplemented by manual searching methods, was performed to identify pertinent articles. Diagnostic accuracy parameters, including sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the curve (AUC), were calculated with corresponding 95% confidence intervals (CIs).

RESULTS

Twenty-one studies with 4753 NPC cases and 31875 non-NPC controls were included. The pooled sensitivities for VCA-IgA+EA-IgA, VCA-IgA+EBNA1-IgA, VCA-IgA+Rta-IgG, and VCA-IgA+ EA-IgA+Rta-IgG were 0.89, 0.93, 0.94, and 0.94, respectively. Pooled specificities were 0.89, 0.88, 0.90, and 0.95, respectively. The PLRs were 8.1, 7.6, 9.4, and 17.4, respectively. Pooled NLRs were 0.12, 0.08, 0.07, and 0.07, respectively. Pooled DORs were 66, 95, 135, and 261, respectively. Pooled AUCs were 0.94, 0.96, 0.97, and 0.94, respectively.

CONCLUSION

These four combined assays based on EBV-related antibodies show diagnostic accuracy. The three-marker assay of VCA-IgA, EA IgA, and Rta-IgG has the best performance. Given the aspect of cost-benefit, VCA-IgA combined with EBNA1-IgA or Rta-IgG could become the preferred serodiagnostic strategy for NPC screening and early diagnosis.

Development of a Duplex Serological Multiplex Assay for the Simultaneous Detection of Epstein-Barr Virus IgA and IgG Antibodies in Nasopharyngeal Carcinoma Patients

Epstein-Barr virus (EBV) IgA and IgG antibodies in serum from nasopharyngeal carcinoma (NPC) patients are well-established markers for EBV-positive NPC. Luminex-based multiplex serology can analyze antibodies to multiple antigens simultaneously; however, the detection of both IgA and IgG antibodies requires separate measurements. Here we describe the development and validation of a novel duplex multiplex serology assay, which can analyze IgA and IgG antibodies against several antigens simultaneously. Secondary antibody/dye combinations, as well as serum dilution factors, were optimized, and 98 NPC cases matched to 142 controls from the Head and Neck 5000 study (HN5000) were assessed and compared to data previously generated in separate IgA and IgG multiplex assays. EBER in situ hybridization (EBER-ISH) data available for 41 tumors was used to calibrate antigen-specific cut-offs using receiver operating characteristic (ROC) analysis with a prespecified specificity of ≥90%. A directly R-Phycoerythrin-labeled IgG antibody in combination with a biotinylated IgA antibody and streptavidin-BV421 reporter conjugate was able to quantify both IgA and IgG antibodies in a duplex reaction in a 1:1000 serum dilution. The combined assessment of IgA and IgG antibodies in NPC cases and controls from the HN5000 study yielded similar sensitivities as the separate IgA and IgG multiplex assays (all > 90%), and the duplex serological multiplex assay was able to unequivocally define the EBV-positive NPC cases (AUC = 1). In conclusion, the simultaneous detection of IgA and IgG antibodies provides an alternative for the separate IgA/IgG antibody quantification and may present a promising approach for larger NPC screening studies in NPC endemic areas.

The role of Epstein-Barr virus in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a metastasis-prone malignancy closely associated with the Epstein-Barr virus (EBV). Despite ubiquitous infection of EBV worldwide, NPC incidences displayed predominance in certain ethnic groups and endemic regions. The majority of NPC patients are diagnosed with advanced-stage disease, as a result of anatomical isolation and non-specific clinical manifestation. Over the decades, researchers have gained insights into the molecular mechanisms underlying NPC pathogenesis as a result of the interplay of EBV infection with several environmental and genetic factors. EBV-associated biomarkers were also used for mass population screening for the early detection of NPC. EBV and its encoded products also serve as potential targets for the development of therapeutic strategies and tumour-specific drug delivery. This review will discuss the pathogenic role of EBV in NPC and efforts in exploiting the potential of EBV-associated molecules as biomarkers and therapeutic targets. The current knowledge on the role of EBV and its associated products in NPC tumorigenesis, development and progression will offer a new outlook and potential intervention strategy against this EBV-associated malignancy.

Resistin Promotes Nasopharyngeal Carcinoma Metastasis through TLR4-Mediated Activation of p38 MAPK/NF-κB Signaling Pathway

NPC is a type of malignant tumor with a high risk of local invasion and early distant metastasis. Resistin is an inflammatory cytokine that is predominantly produced from the immunocytes in humans. Accumulating evidence has suggested a clinical association of circulating resistin with the risk of tumorigenesis and a relationship between blood resistin levels and the risk of cancer metastasis. In this study, we explored the blood levels and the role of resistin in NPC. High resistin levels in NPC patients were positively associated with lymph node metastasis, and resistin promoted the migration and invasion of NPC cells in vitro. These findings were also replicated in a mouse model of NPC tumor metastasis. We identified TLR4 as a functional receptor in mediating the pro-migratory effects of resistin in NPC cells. Furthermore, p38 MAPK and NF-κB were intracellular effectors that mediated resistin-induced EMT. Taken together, our results suggest that resistin promotes NPC metastasis by activating the TLR4/p38 MAPK/NF-κB signaling pathways.

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.

Association between solid fuel use and seropositivity against Epstein-Barr virus in a high-risk area for nasopharyngeal carcinoma

Epstein-Barr virus (EBV) is one of the risk factors of nasopharyngeal carcinoma (NPC), and understanding the modifiable risk factors of EBV activation is crucial in the prevention of NPC. In this study, we aimed to investigate the association between solid fuel use and EBV seropositivity in a high-risk area of NPC. Our study was based on the baseline findings from an ongoing population-based prospective cohort in Sihui county in Southern China. We explored the association between current use of solid fuel in cooking and EBV seropositivity, and NPC-related EBV activation, using logistic regression models. Stratification analyses were further conducted to assess potential effect modifiers. We also examined the impact of frequency and duration of solid fuel use, and switch in fuel types, on EBV seropositivity among ever users. Of the 12,579 participants included in our analysis, 4088 (32.5%) were EBV seropositive and 421 (3.3%) were high risk for NPC-related EBV activation. Solid fuel use was associated with a higher risk of EBV seropositivity and NPC-related EBV activation, with odds ratios (ORs) of 1.33 (95%CI: 1.01, 1.76) and 1.81 (95%CI: 1.03, 3.18), respectively. Higher risk of EBV seropositivity was observed for those who did not use ventilation apparatus and those who consumed salted food. Among ever users, OR was highest for participants with more than 40 years of solid fuel exposure (1.17, 95%CI: 1.00-1.37) and who have been constantly using solid fuel (1.30, 95%CI: 0.96-1.75). We did not find a statistically significant impact of cooking frequency on EBV seropositivity. The identification of solid fuel as a risk factor for EBV activation is of great value for understanding the etiology of NPC. Our findings also have important public health implications given the fact that a third of the global population still lack access to clean cooking, especially in low resource settings.

Integration Profiling Between Plasma Lipidomics, Epstein–Barr Virus and Clinical Phenomes in Nasopharyngeal Carcinoma Patients

Plasma lipidomics has been commonly used for biomarker discovery. Studies in cancer have suggested a significant alteration of circulating metabolite profiles which is correlated with cancer characteristics and treatment outcome. However, the lipidomics characteristics of nasopharyngeal carcinoma (NPC) have rarely been studied. We previously described the phenomenon of lipid droplet accumulation in NPC cells and showed that such accumulation could be regulated by latent infection of Epstein–Barr virus (EBV). Here, we compared the plasma lipidome of NPC patients to that of healthy controls by liquid chromatography-tandem mass spectrometry (LC–MS/MS). We found 19 lipids (e.g., phosphatidylinositols 18:0/20:4 and 18:0/18:2 and free fatty acid 22:6) to be remarkably decreased, whereas 2 lipids (i.e., diacylglycerols 16:0/16:1 and 16:0/20:3) to be increased, in the plasma of NPC patients, compared with controls. Different lipid profiles were also observed between patients with different titers of EBV antibodies (e.g., EA-IgA and VCA-IgA) as well as between patients with and without lymph node or distant organ metastasis. In conclusion, plasma lipidomics might help to differentiate NPC cases from controls, whereas EBV infection might influence the risk and prognosis of NPC through modulating lipid metabolism in both tumor cells and peripheral blood.

Nasopharyngeal carcinoma patients from Norway show elevated Epstein-Barr virus IgA and IgG antibodies prior to diagnosis

BACKGROUND

IgA antibodies against few Epstein-Barr virus (EBV) proteins are established serological markers for nasopharyngeal carcinoma (NPC). We recently validated a novel, comprehensive EBV marker panel and showed that IgA, but also IgG antibodies against multiple EBV proteins are highly sensitive and specific for EBV-positive NPC at diagnosis. However, data about these novel biomarkers as prospective markers for NPC are sparse.

METHODS

This study included 30 incident NPC cases and 60 matched controls from the Norwegian Janus Serum Bank. For 21 NPCs, molecular EBV and human papillomavirus (HPV) status were assessed by EBER-ISH and HPV DNA/RNA testing by PCR, respectively. IgA and IgG serum antibodies against 17 EBV antigens were analyzed in prediagnostic sera of cases (median lead time 14 years) and controls using multiplex serology. Sensitivities were calculated using receiver operating characteristic analysis pre-specified to yield 90% specificity in the control group. From 10 cases, serial samples were available.

RESULTS

Quantitative EBV antibody levels were significantly elevated among all cases (p < 0.05) for three IgA and six IgG antibodies. The highest sensitivities for defining 12 EBER-ISH-positive NPCs were observed for BGLF2 IgA (67%) and BGLF2 IgG (83%). Increased IgA and IgG antibody levels between the first and last draw before diagnosis were observed for EBER-ISH positive, but not for EBER-ISH negative NPCs. Among 21 molecularly analyzed NPCs, 4 EBER-ISH negative NPCs showed concomitant positivity to HPV type-specific DNA and RNA; 3 NPCs were HPV16 and 1 NPC was HPV18 positive.

CONCLUSION

Both, EBV IgA and IgG antibody levels are significantly elevated many years before diagnosis of EBV-positive NPCs in Norway, an NPC low-incidence region. This study provides insights into one of the largest available prospective sample collections of NPCs in a non-endemic country.

Environmental factors for Epstein-Barr virus reactivation in a high-risk area of nasopharyngeal carcinoma: a population-based study

Background

Epstein-Barr virus (EBV) reactivation from latent to lytic infection has been considered as a key step in nasopharyngeal carcinoma oncogenesis. However, epidemiological evidence regarding environmental risk factors for EBV reactivation on a population level remains largely lacking.

Methods

We enrolled 1916 randomly selected adults from the general population of Guangdong and Guangxi, China, from 2010 to 2014. Information on environmental factors was collected via a structured interview. Serum immunoglobulin A antibodies against EBV viral capsid antigen and nuclear antigen 1 were measured by enzyme-linked immunosorbent assay to evaluate EBV reactivation status. We used logistic regression to calculate odds ratios (ORs) with 95% confidence intervals (CIs) for the associations of EBV reactivation with various environmental factors.

Results

No associations were observed between EBV reactivation and extensive environmental factors, including alcohol or tea drinking, a history of chronic ear/nose/throat diseases, use of medications or herbs, consumption of salted fish or preserved foods, oral hygiene, sibship structure, and various residential and occupational exposures. Only cigarette smoking was associated with EBV reactivation (current smokers vs never smokers; OR = 1.37; 95% CI = 1.02–1.83), with positive exposure-response trends with increasing intensity, duration, and pack-years of smoking.

Conclusions

Consistent with previous studies, we found an association between cigarette smoking and EBV reactivation. Other examined exposures were not associated with EBV reactivation. These null results could suggest either more complex interactions between exposures and EBV reactivation or a predominant role of host and/or viral genetic variation.

Adiponectin suppresses tumor growth of nasopharyngeal carcinoma through activating AMPK signaling pathway

BACKGROUND

Adiponectin is an adipocyte-secreted cytokine that enhances insulin sensitivity and attenuates inflammation. Although circulating adiponectin level is often inversely associated with several malignancies, its role in the development of nasopharyngeal carcinoma (NPC) remains unclear. Here, we investigated the clinical association between circulating adiponectin level and NPC, and examined the impact of adiponectin, as well as the underlying mechanisms, on NPC growth both in vitro and in vivo.

METHODS

The association between circulating adiponectin level and the risk of developing NPC was assessed in two different cohorts, including a hospital-based case-control study with 152 cases and 132 controls, and a nested case-control study with 71 cases and 142 controls within a community-based NPC screening cohort. Tumor xenograft model, cell proliferation and cycle assays were applied to confirm the effects of adiponectin on NPC growth in cultured cells and in xenograft models. We also investigated the underlying signaling mechanisms with various specific pharmacological inhibitors and biochemistry analysis.

RESULTS

High adiponectin levels were associated with a monotonic decreased trend of NPC risk among males in both the hospital-based case-control study and a nested case-control study. In vitro, recombinant human full-length adiponectin significantly inhibited NPC cell growth and arrested cell cycle, which were dependent on AMPK signaling pathway. The growth of xenograft of NPC tumor was sharply accelerated in the nude mice carrying genetic adiponectin deficiency. An adiponectin receptor agonist, AdipoRon, displayed strong anti-tumor activity in human xenograft models.

CONCLUSIONS

These findings demonstrated for the first time that circulating adiponectin is not only inversely associated with NPC, but also controls the development of NPC via AMPK signaling pathway. Stimulation of adiponectin function may become a novel therapeutic modality for NPC.

A potent and protective human neutralizing antibody targeting a novel vulnerable site of Epstein-Barr virus

Epstein-Barr virus (EBV) is associated with a range of epithelial and B cell malignancies as well as autoimmune disorders, for which there are still no specific treatments or effective vaccines. Here, we isolate EBV gH/gL-specific antibodies from an EBV-infected individual. One antibody, 1D8, efficiently neutralizes EBV infection of two major target cell types, B cells and epithelial cells. In humanized mice, 1D8 provides protection against a high-dose EBV challenge by substantially reducing viral loads and associated tumor burden. Crystal structure analysis reveals that 1D8 binds to a key vulnerable interface between the D-I/D-II domains of the viral gH/gL protein, especially the D-II of the gH, thereby interfering with the gH/gL-mediated membrane fusion and binding to target cells. Overall, we identify a potent and protective neutralizing antibody capable of reducing the EBV load. The novel vulnerable site represents an attractive target that is potentially important for antibody and vaccine intervention against EBV infection.

Advances in pathogenesis and precision medicine for nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a squamous carcinoma with apparent geographical and racial distribution, mostly prevalent in East and Southeast Asia, particularly concentrated in southern China. The epidemiological trend over the past decades has suggested a substantial reduction in the incidence rate and mortality rate due to NPC. These results may reflect changes in lifestyle and environment, and more importantly, a deeper comprehension of the pathogenic mechanism of NPC, leading to much progress in the preventing, screening, and treating for this cancer. Herein, we present the recent advances on the key signal pathways involved in pathogenesis of NPC, the mechanism of Epstein‐Barr virus (EBV) entry into the cell, and the progress of EBV vaccine and screening biomarkers. We will also discuss in depth the development of various therapeutic approaches including radiotherapy, chemotherapy, surgery, targeted therapy, and immunotherapy. These research advancements have led to a new era of precision medicine in NPC.

Association Between Traditional Herbal Diet and Nasopharyngeal Carcinoma Risk: A Prospective Cohort Study in Southern China

Introduction

Prospective evidence for herbal diet and nasopharyngeal carcinoma (NPC) development is absent. We therefore evaluated the associations of herbal soup and herbal tea with NPC in a prospective cohort study in southern China.

Methods

Based on an NPC screening cohort established in 2008-2015, information on herbal diet consumption, potential confounding factors, and Epstein-Barr virus (EBV) antibody levels were collected from 10,179 individuals aged 30-69 years in Sihui city, southern China. Cox regression models were performed to examine herbal diet with NPC risk, and logistic regression models were used to examine herbal diet with EBV reactivation.

Results

During a median of 7.54 years of follow-up, 69 participants developed NPC. Herbal soup consumption was associated with decreased NPC risk, with HRs of 0.31 (95% confidence interval (CI): 0.15-0.62) for the highest intake frequency and 0.29 (95% CI: 0.16-0.51) for a longer duration. However, herbal tea was not significantly associated. Moreover, we identified herbal soup was inversely associated with EBV seropositivity among all the participants at baseline, with the adjusted ORs being 0.78 (95% CI: 0.65-0.93) for immunoglobulin A antibodies against EBV capsid antigens (VCA-IgA) and 0.76 (95% CI: 0.64-0.91) for nuclear antigen 1 (EBNA1-IgA) in those with the highest frequency and 0.70 (95% CI: 0.59-0.84) for VCA-IgA and 0.64 (95% CI: 0.54-0.77) for EBNA1-IgA in those with the longer duration. Inverse associations were also observed in non-NPC individuals.

Conclusions

With inhibition of EBV reactivation by plants, herbal soup could significantly decrease the risk of NPC in endemic areas.

A comprehensive risk score for effective risk stratification and screening of nasopharyngeal carcinoma

Using Epstein-Barr virus (EBV)-based markers to screen populations at high risk for nasopharyngeal carcinoma (NPC) is an attractive preventive approach. Here, we develop a comprehensive risk score (CRS) that combines risk effects of EBV and human genetics for NPC risk stratification and validate this CRS within an independent, population-based dataset. Comparing the top decile with the bottom quintile of CRSs, the odds ratio of developing NPC is 21 (95% confidence interval: 12-37) in the validation dataset. When combining the top quintile of CRS with EBV serology tests currently used for NPC screening in southern China, the positive prediction value of screening increases from 4.70% (serology test alone) to 43.24% (CRS plus serology test). By identifying individuals at a monogenic level of NPC risk, this CRS approach provides opportunities for personalized risk prediction and population screening in endemic areas for the early diagnosis and secondary prevention of NPC.

Development and validation of a flexible DNA extraction (PAN) method for liquid biopsy of multiple sample types

BACKGROUND

Liquid biopsy is gaining increasing popularity in cancer screening and diagnosis. However, there is no relatively mature DNA isolation method or commercial kit available that is compatible with different LB sample types. This study developed a PAN-sample DNA isolation method (PAN method) for liquid biopsy samples.

METHODS

The PAN method has two key steps, including biosample-specific pretreatments for various LB sample types and high concentration guanidine thiocyanate buffer for lysis and denaturation procedure. Subsequently, the performance of PAN method was validated by a series of molecular analyses.

RESULTS

The PAN method was used to isolate DNA from multiple sample types related to LB, including plasma, serum, saliva, nasopharyngeal swab, and stool. All purified DNA products showed good quality and high quantity. Comparison of KRAS mutation analysis using DNA purified using PAN method versus QIAamp methods showed similar efficiency. Epstein-Barr virus DNA was detected via Q-PCR using DNA purified from serum, plasma, nasopharyngeal swab, and saliva samples collected from nasopharyngeal carcinoma patients. Similarly, methylation sequencing of swab and saliva samples revealed good coverage of target region and high methylation of HLA-DPB1 gene. Finally, 16S rDNA gene sequencing of saliva, swab, and stool samples successfully defines the relative abundance of microbial communities.

CONCLUSIONS

This study developed and validated a PAN-sample DNA isolation method that can be used for different LB samples, which can be applied to molecular epidemiological research and other areas.

Comparison of new magnetic resonance imaging grading system with conventional endoscopy for the early detection of nasopharyngeal carcinoma

BACKGROUND

Although stratifying individuals with respect to nasopharyngeal carcinoma (NPC) risk with Epstein-Barr virus-based markers is possible, the performance of diagnostic methods for detecting lesions among screen-positive individuals is poorly understood.

METHODS

The authors prospectively evaluated 882 participants aged 30 to 70 years who were enrolled between October 2014 and November 2018 in an ongoing, population-based NPC screening program and had an elevated NPC risk. Participants were offered endoscopy and magnetic resonance imaging (MRI), and lesions were identified either by biopsy at a follow-up endoscopy or further contact and linkage to the local cancer registry through December 31, 2019. The diagnostic performance characteristics of endoscopy and MRI for NPC detection were investigated.

RESULTS

Eighteen of 28 identified NPC cases were detected by both methods, 1 was detected by endoscopy alone, and 9 were detected by MRI alone. MRI had significantly higher sensitivity than endoscopy for NPC detection overall (96.4% vs 67.9%; P_difference = .021) and for early-stage NPC (95.2% vs 57.1%; P = .021). The sensitivity of endoscopy was suggestively lower among participants who had previously been screened in comparison with those undergoing an initial screening (50.0% vs 81.2%; P = .11). The authors observed a higher overall referral rate by MRI versus endoscopy (17.3% vs 9.1%; P < .001). Cases missed by endoscopy had early-stage disease and were more commonly observed for tumors originating from the pharyngeal recess.

CONCLUSIONS

MRI was more sensitive than endoscopy for NPC detection in the context of population screening but required the referral of a higher proportion of screen-positive individuals. The sensitivity of endoscopy was particularly low for individuals who had previously been screened.

Serum EA-IgA and D-dimer, but not VCA-IgA, are associated with prognosis in patients with nasopharyngeal carcinoma: a meta-analysis

Background

Patients with nasopharyngeal cancer (NPC) differ in prognosis, even at the same stage; therefore, new biomarkers are urgently required to identify early-stage NPC patients at high risk of poor prognosis. Although Epstein–Barr virus (EBV) DNA has been used for prognosis, the value of many other biomarkers expressed during the infection cycle of EBV remains unclarified. This study aimed to evaluate the prognostic potential of EA-IgA, VCA-IgA and d-dimer in patients with NPC.

Methods

Electronic databases, including PubMed, Embase and Web of Science, were searched up to February 1, 2021. Pooled data were extracted from studies that evaluated the relationship between NPC and overall survival (OS), distant metastasis-free survival (DMFS) or disease-free survival (DFS) and then were subjected to a meta-analysis.

Results

Nine studies with 5729 patients were included in this meta-analysis. In patients with NPC, EA-IgA levels significantly predicted OS (HR = 1.63, 95% CI 1.07–2.48). d-Dimer levels significantly predicted OS (HR = 1.75, 95% CI 1.24–2.47) and DMFS (HR = 1.91, 95% CI 1.31–2.79). However, high levels of VCA-IgA were not associated with OS (HR = 1.24, 95% CI 0.95–1.60), DMFS (HR = 1.41, 95% CI 0.92–2.17) or DFS (HR = 2.39, 95% CI 0.78–7.26).

Conclusions

The present findings reveal that EA-IgA and d-dimer, but not VCA-IgA, can be used as prognostic biomarkers in NPC.

Plasma Epstein-Barr virus DNA and risk of nasopharyngeal carcinoma in a prospective seropositive population

OBJECTIVE

Plasma Epstein-Barr virus (EBV) DNA is considered a biomarker for nasopharyngeal carcinoma (NPC). However, its long-term role in NPC development is unclear.

MATERIALS AND METHODS

A total of 1363 participants seropositive for EBV VCA-IgA and EBNA1-IgA in a community-based NPC screening program in southern China were tested for plasma EBV DNA levels by real-time qPCR between 2008 and 2015. New NPC cases were confirmed by active follow-up approach and linkage to local cancer registry through the end of 2016. Cox proportional hazards regression analysis was performed to calculate the hazard ratios (HRs) for NPC risk with plasma EBV DNA.

RESULTS

Thirty patients were newly diagnosed during a median 7.5 years follow-up. NPC incidence increased with the plasma EBV DNA load ranging from 281.46 to 10,074.47 per 100,000 person-years in participants with undetectable and ≥ 1000 copies/ml levels; the corresponding cumulative incidence rates were 1.73 and 50%. Furthermore, plasma EBV DNA loads conferred an independent risk for NPC development after adjustment for other risk factors, with HRs of 7.63 for > 3-999 copies/ml and 39.79 for ≥1000 copies/ml. However, the HRs decreased gradually after excluding NPC cases detected in the first 2 to 3 years and became statistically nonsignificant by excluding cases detected during the first 4 years.

CONCLUSION

Elevated plasma EBV DNA can predict NPC risk over 3 years. Monitoring plasma EBV DNA can be used as a complementary approach to EBV serological antibody-based screening for NPC.

Prospective assessment of a nasopharyngeal carcinoma risk score in a population undergoing screening

Despite evidence suggesting the utility of Epstein-Barr virus (EBV) markers to stratify individuals with respect to nasopharyngeal carcinoma (NPC) risk in NPC high-risk regions, no validated NPC risk prediction model exists. We aimed to validate an EBV-based NPC risk score in an endemic population undergoing screening for NPC. This prospective study was embedded within an ongoing NPC screening trial in southern China initiated in 2008, with 51 235 adult participants. We assessed the score's discriminatory ability (area under the receiver-operator-characteristics curve, AUC). A new model incorporating the EBV score, sex and family history was developed using logistic regression and internally validated using cross-validation. AUCs were compared. We also calculated absolute NPC risk combining the risk score with population incidence and competing mortality data. A total of 151 NPC cases were detected in 2008 to 2016. The EBV-based score was highly discriminating, with AUC = 0.95 (95% CI = 0.93-0.97). For 90% specificity, the score had 87.4% sensitivity (95% CI = 81.0-92.3%). As specificity increased from 90% to 99%, the positive predictive value increased from 2.4% (95% CI = 1.9-3.0%) to 12.5% (9.9-15.5%). Correspondingly, the number of positive tests per detected NPC case decreased from 272 (95% CI = 255-290) to 50 (41-59). Combining the score with other risk factors (sex, first-degree family history of NPC) did not improve AUC. Men aged 55 to 59 years with the highest risk profile had the highest 5-year absolute NPC risk of 6.5%. We externally validated the discriminatory accuracy of a previously developed EBV score in a high-risk population. Adding nonviral risk factors did not improve NPC prediction.

The diagnostic value of EBV-DNA and EBV-related antibodies detection for nasopharyngeal carcinoma: a meta-analysis

BACKGROUND

Numerous individual studies have investigated the diagnostic value of EBV-DNA, EA-IgA, VCA-IgA, EBNA1-IgA and Rta-IgG detection for nasopharyngeal carcinoma (NPC), but the conclusions remain controversial. This meta-analysis aimed to determine the value of EBV-DNA, EA-IgA, VCA-IgA, EBNA1-IgA and Rta-IgG detection in the diagnosis of NPC.

METHODS

PROSPERO registration number: CRD42019145532. PubMed, EMBASE, Cochrane Library, and Chinese data libraries (Wanfang, CNKI, and CBM) were searched up to January 2019. The pooled sensitivity, specificity, and positive likelihood, negative likelihood, and diagnostic odds ratios were conducted in this meta-analysis. Summary receiver operating characteristic curves evaluated the test-performance global summary. Publication bias was examined by Deek's funnel plot asymmetry test.

RESULTS

Forty-seven studies with 8382 NPC patients (NPC group) and 15,089 individuals without NPC (Control group) were included in this meta-analysis. The sensitivity, specificity, positive likelihood (+ LR), negative likelihood (-LR), DOR and AUC of EBV-DNA in diagnosis of NPC were: 0.76 (95% CI 0.73-0.77), 0.96 (95% CI 0.95-0.97), 14.66 (95% CI 9.97-21.55), 0.19 (95% CI 0.13-0.28), 84 (95% CI 50.45-139.88), 0.96 (SE: 0.001), and 0.55 (95% CI 0.54-0.57), 0.96 (95% CI 0.96-0.97), 12.91 (95% CI 9.55-17.45), 0.35 (95% CI 0.29-0.43), 39.57 (95% CI 26.44-59.23), 0.94 (SE: 0.002) for the EA-IgA, and 0.85 (95% CI 0.84-0.85), 0.89 (95% CI 0.88-0.89), 6.73 (95% CI5.38-8.43), 0.17 (95% CI 0.12-0.23), 43.03 (95% CI 31.51-58.76), 0.93 (SE: 0.007) for the VCA-IgA, and 0.86 (95% CI 0.85-0.88), 0.87 (95% CI 0.88-0.90), 7.55 (95% CI 5.79-9.87), 0.16 (95% CI 0.13-0.19), 50.95 (95% CI 34.35-75.57), 0.94 (SE: 0.008) for the EBNA1-IgA, and 0.70 (95% CI 0.69-0.71), 0.94 (95% CI 0.94-0.95), 9.84 (95% CI 8.40-11.54), 0.25 (95% CI 0.21-0.31), 40.59 (95% CI 32.09-51.35), 0.95 (SE: 0.005) for the Rta-IgG. The EBV-DNA had larger AUC compared with other EBV-based antibodies (P < 0.05), while the difference between EA-IgA, VCA-IgA, EBNA1-IgA and Rta-IgG was not statistically significant (P > 0.05).

CONCLUSIONS

EBV-DNA, VCA-IgA, EBNA1-IgA and Rta-IgG detection have high accuracy in early diagnosis NPC. In addition, EBV-DNA detection has the higher diagnosis accuracy in NPC. On the other hand, EA-IgA is suitable for the diagnosis but not NPC screening.

Prognostic Value of Serum Epstein-Barr Virus Antibodies and Their Correlation with TNM Classification in Patients with Locoregionally Advanced Nasopharyngeal Carcinoma

Purpose

This study assessed the correlation between Epstein-Barr virus (EBV) biomarkers and the eighth American Joint Committee on Cancer staging system and the prognostic values of IgG antibodies against replication and transcription activator (Rta-IgG), IgA antibodies against Epstein-Barr nuclear antigen 1, and BamH1 Z transactivator (Zta-IgA) in locoregionally advanced nasopharyngeal carcinoma (NPC) patients.

Materials and Methods

Serum EBV antibody levels were measured by enzyme-linked immunosorbent assay in 435 newly diagnosed stage III-IVA NPC patients administered intensity-modulated radiation therapy±chemotherapy. The primary endpoint was progression-free survival (PFS).

Results

Rta-IgG and Zta-IgA levels were positively correlated with the N category and clinical stage. Patients with high Rta-IgG levels (> 29.07 U/mL) showed a significantly inferior prognosis as indicated by PFS (77% vs. 89.8%, p=0.004), distant metastasis–free survival (DMFS) (88.3% vs. 95.8%, p=0.021), and local recurrence-free survival (LRFS) (91.2% vs. 98.3%, p=0.009). High Rta-IgG levels were also significantly associated with inferior PFS and LRFS in multivariable analyses. In the low-level EBV DNA group (≤ 1,500 copies/mL), patients with high Rta-IgG levels had significantly inferior PFS and DMFS (both p < 0.05). However, in the high-level EBV DNA group, Rta-IgG levels were not significantly associated with PFS, DMFS, and LRFS. In the advanced T category (T3–4) subgroup, high Rta-IgG levels were also significantly associated with inferior PFS, DMFS, and LRFS (both p < 0.05).

Conclusion

Rta-IgG and Zta-IgA levels were strongly correlated with the TNM classification. Rta-IgG level was a negative prognostic factor in locoregionally advanced NPC patients, especially those with advanced T category or low EBV DNA level.

Targeting the signaling in Epstein-Barr virus-associated diseases: mechanism, regulation, and clinical study

Epstein–Barr virus-associated diseases are important global health concerns. As a group I carcinogen, EBV accounts for 1.5% of human malignances, including both epithelial- and lymphatic-originated tumors. Moreover, EBV plays an etiological and pathogenic role in a number of non-neoplastic diseases, and is even involved in multiple autoimmune diseases (SADs). In this review, we summarize and discuss some recent exciting discoveries in EBV research area, which including DNA methylation alterations, metabolic reprogramming, the changes of mitochondria and ubiquitin-proteasome system (UPS), oxidative stress and EBV lytic reactivation, variations in non-coding RNA (ncRNA), radiochemotherapy and immunotherapy. Understanding and learning from this advancement will further confirm the far-reaching and future value of therapeutic strategies in EBV-associated diseases.

Association between Antibody Responses to Epstein-Barr Virus Glycoproteins, Neutralization of Infectivity, and the Risk of Nasopharyngeal Carcinoma

Epstein-Barr virus (EBV) is a human oncogenic gammaherpesvirus that infects over 90% of humans in the world and is causally associated with a spectrum of epithelial and B-cell malignancies such as nasopharyngeal carcinoma (NPC). A prophylactic vaccine against EBV is called for, but no approved vaccine is available yet.

While Epstein-Barr virus (EBV) is the major cause of nasopharyngeal carcinoma (NPC), the value of the humoral immune response to EBV glycoproteins and NPC development remains unclear. Correlation between antiglycoprotein antibody levels, neutralization of EBV infectivity, and the risk of NPC requires systematic study. Here, we applied a cytometry-based method and enzyme-linked immunosorbent assay to measure neutralization of infectivity and antibody response to EBV glycoproteins (gH/gL, gB, gp350, and gp42) of plasma samples from 20 NPC cases and 20 high-risk and 20 low-risk healthy controls nested within a screening cohort in Sihui, southern China. We found that NPC cases have similar plasma neutralizing activity in both B cells and epithelial cells and EBV glycoprotein-specific IgA and IgG antibody levels compared with those of healthy controls. Significant correlations were observed between gH/gL IgG and gB IgG and the neutralizing ability against EBV infection of epithelial cells and B cells. These results indicate that a high level of glycoprotein antibodies may favor protection against primary EBV infection, instead of being low-risk biomarkers for NPC in long-term EBV-infected adults. In conclusion, this study provides novel insights into the humoral immune response to EBV infection and NPC development, providing valuable leads for future research that is important for prevention and treatment of EBV-related diseases.

IMPORTANCE Epstein-Barr virus (EBV) is a human oncogenic gammaherpesvirus that infects over 90% of humans in the world and is causally associated with a spectrum of epithelial and B-cell malignancies such as nasopharyngeal carcinoma (NPC). A prophylactic vaccine against EBV is called for, but no approved vaccine is available yet. Therefore, EBV remains a major public health concern. To facilitate novel vaccines and therapeutics for NPC, it is of great importance to explore the impact of humoral immune response to EBV glycoproteins before the development of NPC. Therefore, in this study, we systematically assessed the correlation between antiglycoprotein antibody levels, neutralization of EBV infectivity, and the risk of NPC development. These results provide valuable information that will contribute to designing effective prevention and treatment strategies for EBV-related diseases such as NPC.

A combination of two ELISA tests for nasopharyngeal carcinoma screening in endemic areas based on a case-control study

For populations with a high risk of nasopharyngeal carcinoma (NPC) in Guangdong province in southern China, mass screening is the first choice to prevent death from NPC. To improve the performance of NPC screening, we used a combination based on the IgA antibody against the Epstein-Barr virus (EBV) capsid antigen (VCA-IgA) and the IgA antibody against Epstein-Barr virus nuclear antigen 1 (EBNA1-IgA) to NPC screening by enzyme-linked immunosorbent assay (ELISA). A multiplication model was applied to measure the level of the combination. We evaluated the NPC screening effect of the markers.A case-control study was performed to assess the NPC screening effect of the markers. A total of 10,894 serum specimens were collected, including 554 samples from NPC patients and 10,340 samples from healthy controls. In the training stage, 640 subjects were randomly selected, including 320 NPC cases and 320 healthy controls. In the verification stage, 10,254 subjects were used to verify the NPC screening effect of the combination. Receiver operating characteristic (ROC) analysis was performed. In the verification stage, the combination achieved an sensitivity of 91.45%, a specificity of 93.45%, and an area under the ROC curve (AUC) of 0.978 (95% CI [0.968–0.987]). Compared with VCA-IgA and EBNA1-IgA individually, the combination had an improved screening performance. A probability (PROB) calculated by logistic regression model based on VCA-IgA and EBNA1-IgA was applied to NPC screening by ELISA in China. The AUC of the combination was a little bit larger than the PROB. There was a slight increase (3.13%) in the sensitivity of the combination compared to the sensitivity of the PROB, while the specificity was lower for the combination (92.50%) than for the PROB (95.94%). We successfully applied a combination of two ELISA tests based on VCA-IgA and EBNA1-IgA for NPC screening by using a multiplication model. The results suggested that the combination was effective and can be an option for NPC screening.

Efficacy of Chemiluminescence Immunoassays on VCA-IgA and EBNA1-IgA Antibodies of Epstein-Barr Virus in Diagnosing Nasopharyngeal Carcinoma

Background: IgA antibodies against Epstein-Barr virus (EBV) capsid antigen (VCA) and nuclear antigen 1 (EBNA1) have been proposed to facilitate the diagnosis and early detection of nasopharyngeal carcinoma (NPC) in high-incidence regions. However, while new methodologies and new platforms for the detection of VCA-IgA and EBNA1-IgA have become available, proper interassay simultaneous comparisons have not been carried out. The study was to compare the performance of the chemiluminescent immunoassays (CLIA) and enzyme-linked immunosorbent assay (ELISA) for VCA-IgA and EBNA1-IgA antibodies, and to evaluate the levels of EBV antibodies in healthy population from different areas of China.

Methods: CLIA and ELISA for VCA-IgA and EBNA1-IgA were performed in NPC and healthy populations from high-incidence areas of NPC in South China (N=555), medium-incidence areas of NPC in Central China (N=318) and low-incidence areas of NPC in North China (N=379), and the results were compared and analyzed.

Results: (1) The highest sensitivity in total, early and advanced NPC were 91.5% (CLIA for VCA-IgA), 86.4% (CLIA and ELISA-2 for EBNA1-IgA) and 93.6% (CLIA for VCA-IgA). However, the specificity of EBV-IgA measured by CLIA was relatively lower than ELISA. The top three seromarkers with the largest AUC was CLIA for VCA-IgA (AUC: 0.929, 95% CI: 0.905-0.953), ELISA-2 for EBNA1-IgA (AUC: 0.922, 95% CI: 0.896-0.947) and CLIA for EBNA1-IgA (AUC:0.919, 95% CI: 0.893-0.945), respectively. The positive and negative coincidence rates of the two EBNA1-IgA kits were 69.5% and 91.9%, respectively. However, the coincidence rates of VCA-IgA were relatively low. CLIA kits had good repeatability between different laboratories. (2) The positive rates of EBV-IgA antibodies were relatively high in high-incidence areas of NPC (P < 0.017), while there was no significant difference in the antibody positive rates between medium-incidence areas and low-incidence areas of NPC (P > 0.05).

Conclusions: The performance of EBV-IgA antibodies measured by CLIA has good repeatability, higher sensitivity and similar specificity. The higher EBV-IgA positive rate in healthy subjects by CLIA raises concern about its suitability for NPC-risk screening and requires further analysis.

A Randomized Controlled Trial on Evaluation of Plasma Epstein-Barr Virus Biomarker for Early Diagnosis in Patients With Nasopharyngeal Carcinoma

INTRODUCTION

Early diagnosis of nasopharyngeal carcinoma (NPC) remains a major problem in Southern China. Epstein-Barr virus (EBV) biomarkers have been widely used in NPC screening. This study aims to evaluate the early diagnostic performances of individual EBV biomarkers in NPC.

METHODS

The levels of EBV biomarkers-IgA antibodies against EBV nuclear antigen 1 (EBNA1-IgA), EBV capsid antigen (VCA-IgA), EBV early antigen (EA-IgA), EBV BZLF1 transcription activator protein (Zta-IgA) and IgG antibodies against EBV BRLF1 transcription activator protein (Rta-IgG)-from 106 NPC patients (stage I and II) and 150 normal subjects were measured. VCA-IgA and EA-IgA were detected by immunofluorescence assay (IFA), EBNA1-IgA, Rta-IgG and Zta-IgA were measure by enzyme-linked immunosorbent assay (ELISA), and EBV DNA was detected by qPCR. Statistical analyses of a single index were conducted to evaluate the significance of NPC early diagnosis and TNM classification.

RESULTS

The level of EBNA1-IgA, EBV DNA, VCA-IgA, EA-IgA, Rta-IgG and Zta-IgA in early-stage NPC was significantly higher than in healthy controls (all P < 0.001). EBNA1-IgA yielded the biggest area under the curve (AUC) of 0.962 in distinguishing early-stage NPC patients from the normal subjects, with a sensitivity of 91.5% and a specificity of 98.7%. However, EBV biomarker levels were not associated with tumor size (all P > 0.050), whereas four biomarker levels (EBNA1-IgA, EBV DNA, VCA-IgA, EA-IgA) were related to lymph node metastasis (N0 and N1-2), among which EBNA1-IgA and EBV DNA showed good performance. Finally, high correlation was found between VCA-IgA and EA-IgA (r > 0.800).

CONCLUSION

A single EBNA1-IgA exhibits excellent discrimination performance in early diagnosis of NPC and could become a promising marker for NPC screening.

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.

Autocrine INSL5 promotes tumor progression and glycolysis via activation of STAT5 signaling

Metabolic reprogramming plays important roles in development and progression of nasopharyngeal carcinoma (NPC), but the underlying mechanism has not been completely defined. In this work, we found INSL5 was elevated in NPC tumor tissue and the plasma of NPC patients. Plasma INSL5 could serve as a novel diagnostic marker for NPC, especially for serum VCA-IgA-negative patients. Moreover, higher plasma INSL5 level was associated with poor disease outcome. Functionally, INSL5 overexpression increased, whereas knockdown of its receptor GPCR142 or inhibition of INSL5 reduced cell proliferation, colony formation, and cell invasion in vitro and tumorigenicity in vivo. Mechanistically, INSL5 enhanced phosphorylation and nuclear translocation of STAT5 and promoted glycolytic gene expression, leading to induced glycolysis in cancer cells. Pharmaceutical inhibition of glycolysis by 2-DG or blockade of INSL5 by a neutralizing antibody reversed INSL5-induced proliferation and invasion, indicating that INSL5 can be a potential therapeutic target in NPC. In conclusion, INSL5 enhances NPC progression by regulating cancer cell metabolic reprogramming and is a potential diagnostic and prognostic marker as well as a therapeutic target for NPC.

MRI of benign hyperplasia in the nasopharynx: is there an association with Epstein-Barr virus?

AIM

To evaluate whether there is an association between persistently positive plasma Epstein-Barr virus (EBV) DNA and the presence and the change in benign hyperplasia.

MATERIALS AND METHODS

One hundred and seventeen participants with positive-plasma EBV-DNA, but without NPC from previous nasopharyngeal carcinoma (NPC) screening, underwent follow-up magnetic resonance imaging (MRI) and plasma EBV-DNA after 2 years. Logistic regression was used to analyse associations between MRI (benign hyperplasia on the follow-up MRI and change from 2 years earlier), and plasma EBV-DNA, smoking, and age.

RESULTS

At follow-up, EBV-DNA positivity and smoking were independent parameters for the presence of benign hyperplasia (p=0.027 and 0.023 respectively). Compared with participants in whom EBV-DNA became negative (n=44/117 37.6%), those in whom EBV-DNA remained positive (n=73/117 62.4%) had a greater risk of benign hyperplasia developing (previous MRI normal), being stable or processing (52/73 71.2% versus 18/44 40.9%; p=0.001).

CONCLUSION

These results suggest a potential link between benign hyperplasia on MRI and the EBV. As EBV contributes to NPC oncogenesis, future MRI research is warranted to determine if persistent benign hyperplasia is a risk marker for development of NPC.

Validation of an Epstein-Barr Virus Antibody Risk Stratification Signature for Nasopharyngeal Carcinoma by Use of Multiplex Serology

Serological testing for nasopharyngeal carcinoma (NPC) has recently been reinvigorated by the implementation of novel Epstein-Barr virus (EBV)-specific IgA and IgG antibodies from a proteome array. Although proteome arrays are well suited for comprehensive antigen selection, they are not applicable for large-scale studies. We adapted a 13-marker EBV antigen signature for NPC risk identified by proteome arrays to multiplex serology to establish an assay for large-scale studies. Taiwanese NPC cases (n = 175) and matched controls (n = 175) were used for assay validation. Spearman's correlation was calculated, and the diagnostic value of all multiplex markers was assessed independently using the area under the receiver operating characteristic curve (AUC). Two refined signatures were identified using stepwise logistic regression and internally validated with 10-fold cross validation. Array and multiplex serology showed strong correlation for each individual EBV marker, as well as for a 13-marker combined model on continuous data. Two refined signatures with either four (LF2 and BGLF2 IgG, LF2 and BMRF1 IgA) or two (LF2 and BGLF2 IgG) antibodies on dichotomous data were identified as the most parsimonious set of serological markers able to distinguish NPC cases from controls with AUCs of 0.992 (95% confidence interval [CI], 0.983 to 1.000) and 0.984 (95% CI, 0.971 to 0.997), respectively. Neither differed significantly from the 13-marker model (AUC, 0.992; 95% CI, 0.982 to 1.000). All models were internally validated. Multiplex serology successfully validated the original EBV proteome microarray data. Two refined signatures of four and two antibodies were capable of detecting NPC with 99.2% and 98.4% accuracy.

Preliminary evaluation of a candidate international reference for Epstein-Barr virus capsid antigen immunoglobulin A in China

BACKGROUND

The detection of the Epstein-Barr capsid antigen (VCA) immunoglobulin A (IgA) is widely used in the diagnosis of nasopharyngeal carcinoma (NPC), but a reference standard for evaluating the presence of VCA-IgA is not yet available. Therefore, a reference standard is urgently needed for a uniform and quantitative detection of VCA-IgA.

METHODS

A mixed reference serum from three NPC patients diluted with healthy subject serum was made as a potential first international standard for VCA-IgA. VCA-IgA was detected in twenty NPC patients by four ELISA kits and two chemiluminescent immunoassays kits using the reference as a calibration curve. The performance of these six kits was evaluated, and the quantitative results were compared.

RESULTS

Our results showed a good linearity of the reference in different kits. Without reference, the difference of the total coefficient of variation (from 3.98 to 43.11%) and Within-run coefficient of variation (from 2.47 to 19.66%) was large in the 6 kits. The positive and negative coincidence rate between the 6 kits and indirect immunofluorescence for NPC diagnosis was 75% overall agreement, but a difference among the six kits was found, ranging from 55 to 90%. The concentration of VCA-IgA in the 20 NPC samples led in the division into three categories such as negative, low, or medium/high positive, but these concentrations were significantly different within these three categories depending on the kit used of the 6 considered. However,a good correlation (R² = 0.986) was observed between Antu and Beier ELISA kits.

CONCLUSIONS

The reference serum mightbe used as a reference standard for a better comparison of the results from different kits/laboratories. However, the quantitative results of some kits are still inconsistent due to the diversity of VCA antigens.

Multilaboratory Assessment of Epstein-Barr Virus Serologic Assays: the Case for Standardization

IgA antibodies targeting Epstein-Barr virus (EBV) have been proposed for screening for nasopharyngeal carcinoma (NPC). However, methods differ, and the antigens used in these assays differ considerably between laboratories. To enable formal comparisons across a range of established EBV serology assays, we created a panel of 66 pooled serum samples and 66 pooled plasma samples generated from individuals with a broad range of IgA antibody levels. Aliquots from these panels were distributed to six laboratories and were tested by 26 assays measuring antibodies against VCA, EBNA1, EA-EBNA1, Zta, or EAd antigens. We estimated the correlation between assay pairs using Spearman coefficients (continuous measures) and percentages of agreement (positive versus negative, using predefined positivity cutoffs by each assay developer/manufacturer). While strong correlations were observed between some assays, considerable differences were also noted, even for assays that targeted the same protein. For VCA-IgA assays in serum, two distinct clusters were identified, with a median Spearman coefficient of 0.41 (range, 0.20 to 0.66) across these two clusters. EBNA1-IgA assays in serum grouped into a single cluster with a median Spearman coefficient of 0.79 (range, 0.71 to 0.89). Percentages of agreement differed broadly for both VCA-IgA (12% to 98%) and EBNA1-IgA (29% to 95%) assays in serum. Moderate-to-strong correlations were observed across assays in serum that targeted other proteins (correlations ranged from 0.44 to 0.76). Similar results were noted for plasma. We conclude that standardization of EBV serology assays is needed to allow for comparability of results obtained in different translational research studies across laboratories and populations.