Evaluation of Epstein-Barr virus antigen-based immunoassays for serological diagnosis of nasopharyngeal carcinoma

BACKGROUND: Immunofluorescence (IF) assays based on Epstein-Barr virus (EBV)-encoded antigens have traditionally been the preferred approach for serological screening of nasopharyngeal carcinoma (NPC). OBJECTIVES: To compare the performance of two new commercial assays (indicated by COMM) using, respectively, the IF and enzyme-linked immunosorbent assay (ELISA) formats with an in-house IF assay (IFA). STUDY DESIGN: Sera from 163 patients with histologically confirmed NPC, and 98 healthy controls were tested with each of these assays and their results compared. RESULTS: The sensitivity, specificity, positive and negative predictive values, respectively, for the COMM VCA IgA ELISA were 92.6%, 94.9%, 96.8%, 88.6%; for the COMM VCA IgA IFA were 96.9%, 41.8%, 73.5%, 89.1%; for the in-house VCA IgA IFA were 98.2%, 72.4%, 85.6%, 95.9%; for the COMM EA IgA ELISA were 46.6%, 100%, 100%, 53.0%; for the COMM EA IgA IFA were 77.3%, 100%, 100%, 72.6%; and for the in-house EA IgA IFA were 77.9%, 99.0%, 99.2%, 72.9%. CONCLUSIONS: The receiver operating characteristic curves comparison showed a marginal superior accuracy for the COMM VCA IgA ELISA, suggesting this to be used as a high-throughput serological screening assay, with the more specific COMM EA IgA IFA as a follow-up confirmatory assay in this NPC-endemic area.