Comparison of Direct Immunofluorescent Staining, Shell Vial Culture and Tube Culture for the Detection of Varicella-Zoster Virus in Skin Lesions

Kang, Jung Oak; Yu, Hee Joon; Park, Ile Kyu

Abstract

BACKGROUND
For the diagnosis of varicella-zoster virus (VZV) infection, virus culture has been considered the reference method, but it gives delayed results and needs cell culture facilities. Shell vial culture is more rapid, but it also takes 2 days or more and needs cell culture. Immunofluorescent (IF) method has known to be rapid and sensitive. We compared the tube culture, shell vial culture, and direct IF method to find the most efficient diagnostic method. In addition, the MRC-5 cells were compared with A549 cells for the recovery of VZV in culture.
METHODS
A total of 48 specimens were obtained from skin vesicles of patients with clinical herpes zoster. The vesicle smears were stained with FITC-conjugated monoclonal antibody. The vesicle aspirates obtained in 2 mL of viral transport media were inoculated into shell vials and tubes containing MRC-5 and A549 cell monolayers. After 48 h of incubation at 36degrees C the shell vials were stained with VZV-specific monoclonal antibody. The tubes were stained with the same antibody after 3 weeks or when the monolayer showed cytopathic effect.
RESULTS
The positive rates of direct IF, shell vial culture, and tube culture were 67.5%, 87.5%, and 72.5% respectively. The positive rate of direct IF was increased to 96.4% when inadequate specimens for the direct IF were excluded. The MRC-5 and A549 cells showed no significant difference in the isolation rates of VZV in both shell vial and tube culture.
CONCLUSIONS
Direct IF is the most rapid and practical method for the laboratory confirmation of VZV infection when the swab specimen is adequately obtained. The MRC-5 cells are recommended for the tube culture and A549 cells for the shell vial culture.