Sensitivity and specificity of different antibody tests for detecting varicella-zoster virus.

INTRODUCTION: Antibody tests for detecting varicella-zoster virus include the fluorescent-antibody-to-membrane-antigen (FAMA) assay, immune adherence hemagglutination assay (IAHA), enzyme immunoassay (EIA), and the glycoprotein-based enzyme-linked immunosorbent assay (gpELISA). Although FAMA and gpELISA are highly sensitive, FAMA is not available commercially. Therefore, this study was performed to compare potential high-sensitivity tests with commercially available tests. METHODS: Four antibody tests, FAMA, gpELISA, EIA, and IAHA, were performed using sera collected from 32 children aged 7 months-10 years. Using FAMA as a reference, the sensitivity and specificity of gpELISA, EIA, and IAHA were assessed. Subsequently, using gpELISA as a reference, the positive agreement rate of EIA and IAHA was assessed. RESULTS: On a reference scale with FAMA set at 100%, the sensitivity and specificity of the antibody tests were as follows: gpELISA, 67% and 100%; EIA, 67% and 100%; and IAHA, 47% and 100%, respectively. The positive agreement rates of EIA and IAHA relative to gpELISA were 86% and 64%, respectively. CONCLUSIONS: gpELISA had a lower positive rate than did FAMA, and showed comparable sensitivity to that of EIA.

Cytokine production in whole-blood cultures following immunization with an influenza vaccine.

A clinical trial of a quadrivalent split influenza vaccine was performed in the 2014/15 season. Sixty-four subjects aged 6 months to 18 years were enrolled in order to investigate the relationship between cellular and humoral immune responses. Subjects were categorized into two groups by measuring neutralizing antibodies: non-primed naïve/primed or seroconverted/non-seroconverted groups. Whole-blood cultures were stimulated with the H1N1 split antigen before immunization and one month after the first and second immunizations for subjects < 13 years and before and one month after the first dose for those ≥ 13 years in order to investigate cytokine production. Significant amounts of IL-2, IL-12, IL-13, MCP-1, MIP-1ß, and TNF-α were detected from one month after the first dose in the naïve group. In addition to these cytokines, the production of IL-1ß, IL-4, IL-6, IL-8, IL-10, IL-17, G-CSF, and IFN-γ was enhanced one month after the second dose. No significant increase was noted in the primed group, except in the production of IL-10. In seroconverted subjects, the production of IL-2, IL-4, IL-8, IL-10, G-CSF, MCP-1, TNF-α, and IFN-γ increased one month after the first dose, which was earlier than in the naïve group, whereas no significant cytokine response was noted in subjects without seroconversion. Subjects ≥ 13 years were primed and the production of G-CSF, IL-4, and IL-1ß increased in subjects with seroconversion. Whole-blood cultures were also stimulated with the H3N2 split antigen and similar cytokine profiles were obtained. Many cytokines and chemokines, including inflammatory cytokines, were produced in seroconverted, but not non-seroconverted subjects.

Relationship between the frequency of influenza vaccination and cell-mediated immunity.

Despite established guidelines for population-level assessments of immunity after vaccination, standard methods for individual-level analyses have not been established, limiting the ability to optimize vaccination strategies within a particular season. In this study, we evaluated changes in cell-mediated immunity (CMI) with respect to the number of influenza vaccine doses. In particular, the influenza vaccine was administered to 21 adults during the 2015-2016 season. IFN-γ production induced by the influenza vaccine antigens [A (H1N1), A (H3N2), B (Yamagata lineage), and B (Victoria lineage)] increased after the first dose of vaccination in 11, 10, 10, and 11 subjects, respectively. In 5 of 10 (H1N1), 4 of 10 (H3N2), 3 of 9 (Yamagata lineage), and 3 of 8 (Victoria lineage) subjects who did not exhibit an increase in IFN-γ production after the first dose, CMI was enhanced after the second dose. The production of IFN-γ increased after the first or second dose of the vaccine in 16, 14, 13, and 14 of the 21 subjects, respectively. The results of this study showed that two doses of the influenza vaccine effectively enhance CMI in subjects with primary vaccine failure.