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Modification of the HCMV-specific IFN-γ release test (QuantiFERON-CMV) and a novel proposal for its application
Takahiro Kobayashi1, Jun-Ichi Sato1, Kazufumi Ikuta1,2
1Department of Microbiology, Fukushima Medical University School of Medicine, Fukushima.
Insights
A modified interferon-gamma release test (IFN-γ) can monitor human cytomegalovirus (HCMV) risk in immunocompromised patients. This assay also detected immune enhancement after yogurt consumption in healthy volunteers.
Area of Science:
- Immunology
- Virology
- Clinical Diagnostics
Background:
- Human cytomegalovirus (HCMV) poses a significant health risk to immunocompromised individuals, including organ transplant recipients and AIDS patients.
- Effective monitoring of HCMV infection risk in these vulnerable populations requires accessible clinical examinations.
- Current diagnostic methods may not fully capture dynamic changes in cellular immunity relevant to HCMV infection.
Purpose of the Study:
- To adapt the interferon-gamma (IFN-γ) release assay for monitoring HCMV infection risk.
- To evaluate the utility of modified antigens (IE-1, pp65, or UV-inactivated particles) in an IFN-γ release assay for HCMV.
- To explore novel applications of the assay, such as detecting immune modulation.
Main Methods:
- Modification of the QuantiFERON®-CMV assay using different Human Cytomegalovirus (HCMV) antigens: immediate early-1 (IE-1) protein, pp65 protein, or UV-inactivated HCMV particles.
- Testing the dose-dependent response of heparinized peripheral blood from healthy volunteers to pp65 protein.
- Comparing the assay results with an ELISPOT assay.
- Assessing changes in cellular immunity following daily yogurt consumption over 8 weeks.
Main Results:
- The response to pp65 protein demonstrated a clear dose-dependent sigmoid curve, with an optimal concentration range of 1×10³ to 1×10⁵ pg/ml.
- No correlation was found between the results of this modified assay and the ELISPOT assay.
- A significant enhancement in cellular immunity was observed in volunteers after 8 weeks of daily yogurt intake.
- While inter-individual variability in IFN-γ secretion prevented assay normalization, the test proved effective for tracking individual changes in cellular immune activity.
Conclusions:
- The modified IFN-γ release assay shows potential for monitoring HCMV infection risk, particularly in tracking individual immune status.
- The assay's ability to detect immune enhancement suggests a novel application beyond infection monitoring, such as evaluating the impact of dietary interventions like yogurt consumption.
- Further validation is needed, but the assay offers a valuable tool for assessing dynamic changes in cellular immunity relevant to HCMV and potentially other conditions.
Abstract:
Human cytomegalovirus (HCMV) is universally distributed among humans without any adverse effects; however, it induces severe diseases in immunocompromised patients such as organ transplant recipients and AIDS patients. To manage these immunocompromised patients, an easy clinical examination for the monitoring of disease risk is required. In this study, we modified the interferon-γ (IFN-γ) release test (QuantiFERON®-CMV) using HCMV immediate early-1 (IE-1) or pp65 whole proteins, or UV-inactivated HCMV particles as an antigen. The response of heparinized peripheral blood from healthy volunteers to the pp65 protein showed an obvious dose-dependent sigmoid curve, although no correlation was observed between results of this assay and an ELISPOT assay. The addition of pp65 to the blood samples at a final concentration of 1×103 to 1×105 pg/ml was found to be optimum. Using this assay, we observed a significant enhancement in cellular immunity in volunteers after the daily ingestion of yogurt for 8 weeks, which suggested a novel application of the assay in addition to monitoring HCMV infection risk. IFN-γ secretion from peripheral blood cells on HCMV-antigen stimulation differed significantly between individuals; therefore, the assay could not be normalized. Nevertheless, it was found to be particularly useful for observing fluctuations in cellular immune activity on an individual level.
