Detection of specific IgA antibodies to varicella zoster virus in serum of patients with Ramsay Hunt syndrome.
Varicella zoster virus (VZV)-specific IgG and IgA antibody titers were determined in serial serum samples of 23 patients with Ramsay Hunt syndrome by the immunoperoxidase assay. Varicella zoster virus-specific IgG antibodies were found in the first serum samples of all the patients. In 80% of 20 patients in whom a serum sample was available within 5 days after the onset of the disease. VZV-specific IgA antibodies were detected. The second serum sample was VZV-specific IgA-positive in all of the patients. While all the healthy age- and sex-matched control subjects had VZV-specific IgG antibodies, VZV-specific IgA antibodies were detected in a low titer (dilution = 2) in only three of the subjects. By using VZV-specific IgA antibody titers greater than or equal to 2 and greater than or equal to 4 by the immunoperoxidase assay as a "cutoff" for younger and older patients with Ramsay Hunt syndrome, respectively, an early diagnosis of the disease can be obtained in 89% of the younger and in 64% of the older patients by a single serum sample.