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The feasibility of using serum IgM, IgA and IgG antibodies specific to Epstein-Barr virus (EBV) viral capsid antigen (VCA), as determined by immunoperoxidase assay (IPA), for the early diagnosis of mononucleosis was evaluated in 65 patients with infectious mononucleosis (IMN). Control groups consisted of 104 healthy students and 15 cytomegalovirus-infected patients. In the first serum sample obtained upon admission, IgM antibodies (titer > or = 64) to EBV VCA were found in 64 of the 65 IMN patients (98%), while EBV-VCA IgA antibodies (titer > or = 32) were found in 32 patients (49%). In those particular titers, no EBV-VCA IgM or IgA antibodies were found in any of the control sera. EBV-VCA-specific IgM antibodies were also not detected in any of the 15 patients with cytomegalovirus infection. In sera obtained from IMN patients within 10 days of the onset of symptoms, 18 of 19 (95%) were IgM seropositive. This study demonstrates that serum EBV-VCA IgM antibodies (titer > or = 64) as determined by IPA are highly specific (100%) and highly sensitive (98%) and can be of value for the early and rapid diagnosis of EBV-IMN infection.

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.

Herpes simplex virus (HSV)-specific IgG and IgA antibody response in patients with HSV infection and in healthy adults was studied by the immunoperoxidase antibody-membrane antigen (IPAMA) technique. In all HSV infections in which specific IgM antibodies were detected by enzyme-linked immunosorbent assay (ELISA), a significant rise in the titer of HSV IgG and IgA antibodies was found. In contrast, in patients with recurrent herpes labialis in which no specific HSV IgM antibodies were detected by ELISA, HSV IgG and IgA antibodies were not found to fluctuate significantly during the course of infection. A higher geometric mean titer (GMT) for HSV IgG and for IgA antibodies was found in seropositive individuals with a previous history of recurrent HSV than in seropositive individuals without a previous history of recurrent HSV infection. Nineteen of 26 HSV IgG seropositive healthy medical students without a previous history of recurrent HSV infection had HSV IgA antibodies to membrane antigen. The significance of this finding in understanding the mechanism of latency in healthy seropositive individuals without previous history of HSV recurrent infections is discussed.

The feasibility of using elevated Epstein-Barr virus (EBV) specific-IgG antiviral capsid antigen (VCA) and IgA anti-VCA antibody levels as an aid in diagnosis of nasopharyngeal carcinoma (NPC) was analyzed by determination of serum antibody titers to EBV in 54 NPC patients, 114 healthy blood donors, and 40 family members by the immunoperoxidase assay (IPA). No significant difference was found in the prevalence rate of EBV IgG anti-VCA antibodies (titer greater than or equal to 20) between the patient group and the control and family groups (100% vs 92% and 90%, respectively). The prevalence rate of elevated EBV IgG anti-VCA titers (greater than or equal to 80, greater than or equal to 160, greater than or equal to 320, greater than or equal to 640) was significantly higher in the NPC patients than in controls. For example, at an IgG titer of greater than or equal to 320, the prevalence rate was 82% in the NPC patient group and 1.7% in the controls (P less than 0.0001). The prevalence of EBV IgA anti-VCA antibodies (greater than or equal to 10) was significantly higher in the NPC patients than in control and family groups (82% vs 6.1% and 0%, respectively). The prevalence rate for elevated EBV IgA anti-VCA (greater than or equal to 20) was found to be significantly higher (P less than 0.0001) in NPC patients than in the control group (70% vs. 1.7%). A significantly high proportion (P = 0.0004) of NPC patients who had serum EBV IgA anti-VCA titers of less than 20 had elevated IgG titers to VCA greater than or equal to 320 (21% vs 1.7% among controls). It appears that testing for IgG antibodies at a serum dilution of 1:320 and for IgA antibodies at a dilution of 1:20 by the IPA technique comprises the best combination for the differentiation between NPC patients and health controls (91% vs 3.4%), and it is suggested that these be used as screening markers for NPC patients.

The role of herpes simplex virus (HSV) and varicella zoster virus (VZV) in acute peripheral facial palsy (APFP) was evaluated in 153 patients. The sera of patients were examined for IgG and IgA antibodies to HSV and VZV by the immunoperoxidase antibody-membrane antigen (IPAMA) technique. The prevalence of IgG and IgA seropositivity to HSV was significantly higher in the APFP patients than in the matched control group. No significant difference was found in the geometric mean titer (GMT) to HSV antibodies in the APFP patients compared to the matched control groups. The prevalence of IgA antibodies to VZV was significantly higher in the APFP patients group than in the matched control group. The GMT for VZV IgG antibodies was significantly higher in the APFP patients than in the matched control group. No significant difference was found in the GMT of VZV IgA antibodies. Eleven of 83 patients for whom paired sera were available had significantly increased or decreased IgG and IgA antibody titers to VZV on subsequent examination. Four of these patients did not show any evidence of zosterian eruption. These studies support the concept that VZV and HSV might have a role in the etiopathogenesis of APFP in some of the patients.