Detection of Iga Antibody Against Epstein-Barr Virus Nuclear Antigen 1 in Nasopharyngeal Carcinoma Patients by ELISA
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Date
2010-04-07
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Thai Cancer Journal
Abstract
Nasopharyngeal carcinoma (NPC) is a multi-factorial disease caused by genetic, viral (Epstein Barr virus, EBV) and environmental factors. The elevation of IgA antibody titers against EBV viral capsid antigen (VCA) measured by indirect immunofluorescence assay (IFA) had been use as ‘gold standard’ for NPC diagnosis for over thirty years. However, IFA is unsuitable for mass screening among population since it is time-consuming, inconvenient to perform and difficult to standardize. To date, these difficulties of IFA have been solved by using recombinant protein-based enzyme-linked immunosorbent assay (ELISA). The EBV nuclear antigen 1 (EBNA1) is the only latent EBV antigen consistently expressed in NPC tissues. Recently, it has been found that IgA antibody against EBNA1 (IgA/EBNA1) measured by ELISA may be a useful marker for NPC and the early detection of this cancer. The purpose of this study is to evaluate the usefulness of IgA/EBNA1 from a commercial kit in Thai NPC cases. The concentration of serum IgA/EBNA1 was measured in 54 NPC patients and 122 age match healthy controls by using Sinoclone EBV IgA ELISA kit. The normal cut off value (mean+2SD) of serum IgA/EBNA1 showed a relative optical density (rOD) at 1.26 units. Serum IgA/EBNA1 level was positive in 52 (96.30%) out of 54 NPC patients and in 5 (4.10%) out of 122 healthy controls. NPC cases showed significantly higher serum IgA/EBNA1 level than healthy controls (P \< 0.001). In NPC patients, the serum IGA/EBNA1 level was increased with aggressiveness and advance stages of the disease. Detection of IgA/EBNA1 by Sinoclone EBV IgA ELISA kit in serum had a sensitivity, a specificity, positive predictive values and negative predictive values of 96.30, 95.90, 91.23 and 98.32%, respectively, for the diagnosis of NPC. The results of our study suggest that serum IgA/EBNA1 may be a suitable marker for diagnosis and prognosis of NPC in Thailand and that this test may be a useful addition to the panel of tests used for this purpose. Further studies are currently underway to evaluate the effectiveness of this marker as an early detection tool for NPC in Thailand.
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Thai Cancer Journal; Vol.28 No.2 April-June 2008; 83-92