AVIDITY OF EBV VCA-SPECIFIC IGG ANTIBODIES - DISTINCTION BETWEEN RECENT PRIMARY INFECTION, PAST INFECTION AND REACTIVATION

A commercial Epstein-Barr virus (EBV) antivirus capsid antigen (VCA) I gG antibody ELISA and an 'in-house' EBV VCA IgG immunofluorescence ant ibody assay (IFA) were used to detect EBV VCA IgG antibodies in 100 se rum samples collected from organ transplant recipients and immunocompe tent individuals. The avidity of EBV VCA IgG antibodies was determined in the IFA and ELISA using the mild reducing agent 8 M urea to remove low avidity antibodies. The samples were collected from patients who had previously been identified with a primary EBV infection, a reactiv ation of latent infection or evidence of a past EBV infection by means of EBV-specific serology. Using the ELISA, the antibody avidity was l ow in samples collected from patients with recent EBV infection and hi gh in samples collected from patients with a past infection or a react ivation. There was a statistically significant difference of means (P < 0.001) of percentage reduction in optical density values, measured i n the presence of 8 M urea, obtained with samples collected from patie nts with recent infection compared with samples from patients with a p ast infection or a reactivation of latent infection.