Establishment and evaluation of a fluorescent antibody to membrane antigen test for varicella-zoster virus

Objective To develop and evaluate a fluorescent antibody to membrane antigen (FAMA) test for detection of varicella-zoster virus(VZV)-specific antibody in plasma. Methods The FAMA test was established with VZV-infected cells as fixed antigen and fluorescein isothiocyanate labeled goat anti-human IgG as secondary antibody. The sensitivity, specificity and repeatability of the technique were validated. The antibodies in 200 plasma samples were determined with the established test and a commercial ELISA kit. The detection results of two methods were compared using Spearman’s rank correlation test. Results FAMA test had high sensitivity with the detecting limit of 0.04 IU/ml. No cross reaction with other herpesviruses, such as herpes simplex virus (HSV) 1, 2 and human cytomegalovirus was observed. The antibody positive rate and geometric mean titer of 200 samples determined by FAMA test were 93.5% and 1∶18.1, respectively. The result coincidence rate of FAMA test with the ELISA kit was 90.0%.The results of two methods were correlated with Spearman’s rank correlation coefficient 0.49, P<0.000 1. Conclusion The developed method has good sensitivity, specificity and repeatability, and can be applied for detecting anti-VZV antibodies in sera. Key words: Fluorescent antibody technique; Herpesvirus 3, human; Immunoglobulin G