Determination of antibodies directed at EBV proteins expressed in both latent and lytic cycles in nasopharyngeal carcinoma

Abstract

Objectives: Serologic analyses for anti-EBV antibodies used alone usually have low sensitivity for the diagnosis of nasopharyngeal carcinoma (NPC). We assumed that a combined determination of antibodies directed at EBV proteins expressed in both lytic and latent cycles could increase the sensitivity.

Materials and methods: Sixty healthy controls and 100 NPC patients treated with intensity-modulated radiation therapy were recruited for the study. Serial blood samples of NPC patients were collected before, during and after the treatment. The titers of antibodies directed at Rta (IgG), EA (IgG), VCA (IgA), and NA1 (IgA) were determined in duplicate by ELISA.

Results: Results showed that the combined tests of EA and Rta antibodies significantly improved the sensitivity from 89.0% for EA alone to 95%. For VCA or NA1 in combination with the EA test, it was revealed that either the increase of the specificity was minimal, or the decrease of the specificity was unacceptable. Rta, EA, VCA, and NA1 antibody titers in serial samples were followed from 53 patients of complete remission and 9 patients with recurrence or distal metastasis post the treatment for 2 years. However, the trend of antibody titers of Rta, VCA or NA1 in combination with EA failed to indicate a difference between patients with good and poor prognosis.

Conclusion: Combined measurements of anti-Rta and anti-EA antibodies could significantly increase the sensitivity for the diagnosis of NPC while maintain a high specificity.