Assessment of mumps virus-specific antibodies: Comparison of three different enzyme immunoassays and neutralization test.

INTRODUCTION: We evaluated the application of a newly improved enzyme immunoassay (EIA) kit, Mumps IgG Seiken(R), by comparing antibody responses to different EIA kits, and neutralization tests (NTs), using clinical samples. METHODS: Serum samples were collected before and 4-6 weeks after vaccination from 128 children who had no history of mumps or mumps vaccination. Using three different EIA kits, Mumps IgG Seiken(R), a commercial kit from Enzygnost(R), and an in-house kit, mumps-specific IgG antibodies were measured. Anti-mumps antibody responses between each of the EIA kits and NTs were evaluated. RESULTS: Before vaccination, all samples were seronegative, except for three serum samples measured by Mumps IgG Seiken(R), which exhibited equivocal. The antibody-positivity rates and equivocal rates of Mumps IgG Seiken(R) post-vaccination (71.1 % and 23.4 %, respectively) were comparable to those of Enzygnost(R) (74.2 % and 19.5 %, respectively). However, antibody-positivity and equivocal rates were significantly higher and lower than those of in-house kit (51.6 % and 40.6 %, respectively) (p < 0.05). The concordance rates of the kit (68.7 %) were comparable to those of Enzygnost(R) (71.1 %) and higher than those of in-house-developed kit (58.6 %) (p < 0.05). The area under curve of the three EIA kits were 0.801, 0.804, and 0.859; however, the differences did not reach significance. Correlations of the values obtained using three EIA kits with NTs were 0.71, 0.61, and 0.78. CONCLUSION: The newly approved Mumps IgG Seiken(R) showed good correlation with NTs and had lower equivocal rates compared to in-house kit, comparable to Enzygnost(R). This kit may be clinically acceptable for the evaluation of vaccine immunogenicity.