Cross-reactive humoral immunity of clade 2 Oka and MAV/06 strain-based varicella vaccines against different clades of varicella-zoster virus.

The currently used Japanese Oka and Korean MAV/06-attenuated varicella vaccine strains belong to clade 2 genotype varicella-zoster viruses (VZV). More than seven clades of VZV exist worldwide. In this study, we investigated the cross-reactivity of antibodies induced by clade 2 genotype vaccines against VZV strains belonging to clades 1, 2, 3, and 5 using a fluorescent antibody to membrane antigen (FAMA) test. Among 59 donors, 29 were vaccinated with the MAV/06 strain MG1111 (GC Biopharma, South Korea) and the other 30 were vaccinated with the Oka strain VARIVAX (Merck, USA). The sera were titrated using FAMA tests prepared with six different VZV strains (two vaccine strains, one wild-type clade 2 strain, and one each of clade 1, 3, and 5 strains). The ranges of geometric mean titers (GMTs) of FAMA against six different strains were 158.7-206.5 and 157.6-238.9 in MG1111 and VARIVAX groups, respectively. GMTs of the MG1111 group against all six strains were similar; however, GMTs of the VARIVAX group showed differences of approximately 1.5-fold depending on the strains. Nevertheless, the GMTs of the two vaccinated groups for the same strain were not significantly different. These results suggest that both MG1111 and VARIVAX vaccinations induce cross-reactive humoral immunity against other clades of VZV.

Evaluation of a commercial glycoprotein enzyme-linked immunosorbent assay for measuring vaccine immunity to varicella.

PURPOSE: To evaluate a recently marketed commercial glycoprotein enzyme-linked immunosorbent assay (gpEIA) kit, the VaccZyme™ VZV gpEIA, for measuring the immunity of varicella-vaccinated children. MATERIALS AND METHODS: We investigated the accuracy and reproducibility of the VaccZyme™ VZV gpEIA kit for the detection of antibodies to VZV. We also examined the sensitivity, specificity, and correlation between antibody titers calculated with gpEIA versus fluorescent antibody to membrane antigen (FAMA) by using sera of 349 children, ranging from 1 to 6 years old. RESULTS: VaccZyme™ VZV gpEIA gave precise and reproducible intra- and inter-assay results. FAMA and gpEIA titers showed a linear correlation (Pearson correlation coefficient=0.987). The sensitivity and specificity of the VaccZyme™ gpEIA was 31.4% and 100%, respectively, when the guidelines of the gpEIA (<100 mIU/mL) and FAMA 1:4 were adopted as cutoff values. However, the maximum sensitivity and specificity were 88.9% and 95.1%, respectively, with the highest correlation (κ=0.840), if the cutoff values were set with gpEIA at 49.7 mIU/mL and FAMA 1:16. CONCLUSION: These results demonstrate that the VaccZyme™ VZV gpEIA kit gave precise and reproducible data for measuring antibody titer after varicella vaccination. The results also showed that the antibody titer calculated with the VaccZyme™ gpEIA kit strongly correlated with the FAMA titer. However, cutoff values should be re-optimized for the evaluation of vaccine immunity.

Evaluation of a Commercial Glycoprotein Enzyme-Linked Immunosorbent Assay for Measuring Vaccine Immunity to Varicella

PURPOSE: To evaluate a recently marketed commercial glycoprotein enzyme-linked immunosorbent assay (gpEIA) kit, the VaccZyme(TM) VZV gpEIA, for measuring the immunity of varicella-vaccinated children. MATERIALS AND METHODS: We investigated the accuracy and reproducibility of the VaccZyme(TM) VZV gpEIA kit for the detection of antibodies to VZV. We also examined the sensitivity, specificity, and correlation between antibody titers calculated with gpEIA versus fluorescent antibody to membrane antigen (FAMA) by using sera of 349 children, ranging from 1 to 6 years old. RESULTS: VaccZyme(TM) VZV gpEIA gave precise and reproducible intra- and inter-assay results. FAMA and gpEIA titers showed a linear correlation (Pearson correlation coefficient=0.987). The sensitivity and specificity of the VaccZyme(TM) gpEIA was 31.4% and 100%, respectively, when the guidelines of the gpEIA (<100 mIU/mL) and FAMA 1:4 were adopted as cutoff values. However, the maximum sensitivity and specificity were 88.9% and 95.1%, respectively, with the highest correlation (kappa=0.840), if the cutoff values were set with gpEIA at 49.7 mIU/mL and FAMA 1:16. CONCLUSION: These results demonstrate that the VaccZyme(TM) VZV gpEIA kit gave precise and reproducible data for measuring antibody titer after varicella vaccination. The results also showed that the antibody titer calculated with the VaccZyme(TM) gpEIA kit strongly correlated with the FAMA titer. However, cutoff values should be re-optimized for the evaluation of vaccine immunity.