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

Abstract

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 (R 2 = 0.986) was observed between Antu and Beier ELISA kits.

The Link Between Adenoids and Nasopharyngeal Carcinoma

“…In a more recent meta-analysis, EBV DNA gave a higher diagnostic accuracy than its related antibodies (VC-IgA, EBNA1-IgA and Rta-IgG) [132]. Early stages of NPC which sometimes presents with asymptomatic patients can be detected with immunoglobulin A (IgA) antibodies against EBV using various enzyme-linked immunosorbent assay (ELISA) and chemiluminescent immunoassays kits [63,69,133,134]. Similarly, a meta-analysis of 21 studies by Li et al also showed that the presence of VC/IgA in NPC-positive serum is suggestive of the presence of the disease [135].…”