Figure 1 shows a positive indirect fluorescent antibody serological test for herpes simplex virus-1 (HSV-1) immunoglobulin G (IgG) antibody. The apple-green fluorescent cells indicate antibody-antigen complex formation detected by the conjugate, fluorescein isothiocyanate-labeled antihuman IgG. Cells not expressing HSV-1 antigen are stained orange-red by Evan’s Blue counter stain. The image was captured using the Pathway Bioimager (BD Bioscience).  

Figure 2 shows an enlarged image of the fluorescent cells captured using the Pathway Bioimager with a Nipkow disk confocal module (BD Bioscience).   

The HSV-1 IgG indirect fluorescent antibody test was used to demonstrate detection of HSV-1 IgG antibodies in human serum. The procedure is accomplished in two steps. In step one, human serum is brought into contact with the antigenic substrate (HSV-1 infected cells fixed to a microscope slide), followed by washing in buffer to remove unbound protein. The second step involves adding a fluorescein-labeled antihuman IgG antibody to the test wells, followed by washing and examination using a fluorescent microscope. 

Indirect fluorescent antibody testing for serum antibodies to infectious agents is commonly used to assess the immune status of an individual following natural exposure (infection) or vaccination.