Comparison of cytomegalovirus (CMV) enzyme-linked immunosorbent spot and CMV quantiferon gamma interferon-releasing assays in assessing risk of CMV infection in kidney transplant recipients

Tackling CMV in Transplant Recipients: Past, Present, and Future

Cytomegalovirus (CMV), a beta-herpesvirus capable of maintaining lifelong latency, presents a substantial risk to transplant recipients, resulting in significant morbidity and mortality among both hematopoietic stem cell and solid organ transplantation recipients. Recent advances have shifted management from reactive approaches, such as preemptive therapy, to preventive strategies to reduce active infections and disease burden. Letermovir, a selective CMV terminase inhibitor, has emerged as a critical prophylactic agent in high-risk transplant populations, significantly lowering infection rates and improving survival with fewer adverse effects than older antivirals. Maribavir, a UL97 kinase inhibitor, is another recently approved promising option for treating CMV, especially in patients with ganciclovir-resistant or refractory CMV infections. Despite these achievements, the risk of late-onset CMV infection after prophylaxis discontinuation remains a significant clinical challenge. Current research seeks to refine prophylactic regimens and develop advanced diagnostic tools, notably interferon-gamma release assays that measure CMV-specific T cell responses. These immunologic assays may help clinicians identify individuals capable of controlling CMV replication, thus guiding the safer discontinuation of prophylaxis and reducing unnecessary drug exposure. Conversely, patients lacking robust immune reconstitution could be targeted for extended prophylaxis or closer follow-up. Looking into the future, ongoing innovations in immune monitoring and antiviral development will likely lead to a more personalized approach to CMV prevention and treatment, optimizing care based on patient-specific risk profiles and immune competence. As this field continues to evolve, integrating novel therapies, improved diagnostics, and immunity-driven protocols holds promise for further reducing CMV-related complications and improving overall outcomes for transplant recipients.

Evaluation of the VIDAS Cytomegalovirus (CMV)-IGRA for Assessing CMV-Specific T-Cell Responses in Immunocompetent and Immunosuppressed Individuals

We compared the performance of the VIDAS Cytomegalovirus (CMV)-Interferon-gamma release assay (IGRA) with that of laboratory-developed flow cytometry for intracellular cytokine staining (FC-ICS) for the assessment of CMV-specific interferon-gamma (IFN-γ)-producing T-cell responses (CMV-CMI). A total of 147 blood specimens from 78 adult participants were collected: 11 healthy controls, 34 hematological patients (HP), of which 32 had undergone allogeneic hematopoietic cell transplantation (allo-HCT), and 33 Kidney transplant recipients. Of the 147 specimens, 96 tested positive, 24 negative, 25 indeterminate, and 2 were invalid by the VIDAS CMV IGRA. A total of 137 specimens were tested by FC-ICS, of which 107 returned positive results. There were 27 discrepancies across the assays among specimens yielding interpretable results, of which 14 tested VIDAS CMV IGRA-positive/FC-ICS-negative and 12 VIDAS CMV IGRA-negative/FC-ICS-positive. The overall agreement between immunoassays was 78%, and the Kappa coefficient was 0.34 (0.52 for HP). Differences in identifying CMV-infected (CMV IgG-positive) and uninfected participants (CMV IgG-negative) were noticed across both assays. The overall correlation (rho values) between IFN-γ concentrations (IU/ml) measured by the VIDAS CMV IGRA and CMV-specific IFN-γ-producing T-cell frequencies were 0.27 for CD4+ and 0.33 for CD8+ T cells (p = 0.001). In HP, the correlation was stronger (0.48 for CD4+ and 0.49 for CD8+ T cells). In summary, our data lend support to the potential utility of the VIDAS CMV IGRA to assess CMV-CMI in transplant recipients.

Quantifying Gamma-Interferon from CMV-Specific CD8+ T Cells Defines Protection Against Clinically Significant CMV Infection in Solid Organ Transplant Recipients: The Quanti-CMV Score

The cutoff value of the commercial interferon (IFN)-γ release assay (QuantiFERON-CMV) proposed by the manufacturer is assumed to be predictive. We aimed to determine the optimal cutoff value for protection against clinically significant cytomegalovirus (CMV) infection within 30 days. We analyzed two different cohorts: adult CMV seropositive kidney transplant (KT) recipients with antithymocyte globulin (ATG) induction from the TIMOVAL study and seropositive lung transplant (LT) patients from the CYTOCOR study. The optimal cutoff value was established using Youden's index. We estimated the predictive capacity of the cutoff value through the AUROC and assessed the diagnostic accuracy of the assay at the different cutoff values. We finally evaluated clinical variables that could improve the predictive ability of the assay on a predictive score. Four hundred-four samples from 130 transplant recipients were analyzed. The optimal cutoff value was ≥2.2 IU/mL for both populations, with a positive predictive value of 99% and 99.5% (95% CI, 98-100%) for KT and LT recipients, respectively. The AUROC of the predictive score was 0.85 (95% CI, 0.73-0.97). Using the proposed cutoff value and the Quanti-CMV score may allow the individualization of preventive strategies and serve as an objective tool to support clinical decision-making.

Diagnostic Performance of Two Different Techniques to Quantify CMV-Specific Cell-Mediated Immunity in Intermediate-Risk Seropositive Kidney Transplant Recipients

BACKGROUND

Kidney transplant (KT) recipients at intermediate risk for cytomegalovirus (CMV) infection constitute a potential target for individualized prevention strategies informed by the CMV-specific cell-mediated immunity (CMV-CMI). The optimal method for the functional assessment of CMV-CMI in this group remains unclear.

METHODS

We included 74 CMV-seropositive KT recipients that did not receive T-cell-depleting induction and were managed by preemptive therapy. CMV-CMI was monitored at baseline and months 1, 3, 6, and 12 by intracellular cytokine staining (ICS) and a interferon (IFN)-γ-release assay (QuantiFERON-CMV [QTF-CMV]). Both methods were compared for discriminative capacity (areas under the receiving operating characteristic curve [auROCs]) and diagnostic accuracy to predict protection against high-level (≥1000 IU/mL) CMV DNAemia and/or disease.

RESULTS

Eighteen patients (24.3%) experienced high-level CMV DNAemia or disease. There were no significant differences in the discriminative capacity to predict protection of CMV-specific CD8+ (auROC: 0.719) and CD4+ T-cell counts (auROC: 0.664) enumerated by ICS and IFN-γ production measured by QTF-CMV (auROC: 0.666). Optimal cutoff values of ≥9.8 CMV-specific CD4+ T-cells/µL and ≥5.7 CD8+ T-cells/µL by ICS yielded excellent specificity (95.7% and 86.9%, respectively) and positive predictive values (PPVs) (>98.0%), but a sensitivity below 60%. A reactive QTF-CMV (IFN-γ ≥0.2 IU/mL) provided good sensitivity (81.6%) and PPV (92.5%), at the expense of a poor specificity (22.2%).

CONCLUSIONS

The discriminative capacity to predict immune protection against clinically relevant CMV infection among intermediate-risk KT recipients was comparable for ICS and QTF-CMV. A selected ICS threshold may provide better specificity than the interpretative cut-off values currently recommended for QTF-CMV.

Management of cytomegalovirus in adult solid organ transplant patients: GESITRA-IC-SEIMC, CIBERINFEC, and SET recommendations update

Cytomegalovirus (CMV) infection remains a significant challenge in solid organ transplantation (SOT). The last international consensus guidelines on the management of CMV in SOT were published in 2018, highlighting the need for revision to incorporate recent advances, notably in cell-mediated immunity monitoring, which could alter the current standard of care. A working group including members from the Group for the Study of Infection in Transplantation and the Immunocompromised Host (GESITRA-IC) of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC) and the Spanish Society of Transplantation (SET), developed consensus-based recommendations for managing CMV infection in SOT recipients. Recommendations were classified based on evidence strength and quality using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. The final recommendations were endorsed through a consensus meeting and approved by the expert panel.

Cytomegalovirus Infection After Solid Organ Transplantation: How I Use Cell-Mediated Immune Assays for Management

INTRODUCTION

The pathogenesis and outcome of cytomegalovirus (CMV) infection after solid organ transplantation (SOT) reflects the interplay between viral replication and CMV-specific immunity. Despite advances in its diagnosis and treatment, CMV continues to cause significant morbidity after SOT. Since CMV is an opportunistic pathogen that occurs as a result of impaired pathogen-specific immunity, laboratory assays that measure CMV-specific immune responses may be useful in assisting clinicians in its management.

METHODS AND RESULTS

The author summarizes the evolving and emerging data on the clinical utility of assays that quantify cell-mediated immune responses to CMV in SOT recipients. The majority of publications are observational studies that demonstrate that a lack or deficiency in CMV-specific cell-mediated immunity is correlated with a heightened risk of primary, reactivation, or recurrent CMV after transplantation. A few prospective interventional studies have utilized CMV-specific cell-mediated immune assays in guiding the duration of antiviral prophylaxis among CMV-seropositive SOT recipients. Likewise, CMV-specific cell-mediated immunity assays have been suggested to inform the need for secondary antiviral prophylaxis and immunologic optimization to prevent CMV relapse after treatment.

CONCLUSIONS

CMV-specific cell-mediated immune assays are emerging to assist transplant clinicians in predicting a patient's risk of CMV after transplantation, and these assays have been utilized to individualize the approach to CMV prevention and treatment. The author suggests the conduct of more interventional studies to further solidify the role of CMV-specific cell-mediated immune assays in routine clinical practice.

Pathogen-specific cell-mediated immunity to guide the management of cytomegalovirus in solid organ transplantation: state of the art clinical review

INTRODUCTION

Cytomegalovirus (CMV) is a common opportunistic infection after solid organ transplantation, with significant impact on morbidity and long-term survival. Despite advances in diagnostics and therapeutics, the management of CMV remains very challenging.

AREAS COVERED

This article reviews emerging data on the clinical utility of laboratory assays that quantify cell-mediated immune responses to CMV. Observational studies have consistently demonstrated that a deficiency in pathogen-specific cell-mediated immunity is correlated with a heightened risk of primary, reactivation or recurrent CMV after transplantation. A limited number of interventional studies have recently investigated cell-mediated immune assays in guiding the prevention and treatment of CMV infection after solid organ transplantation.

EXPERT OPINION

The pathogenesis and outcome of CMV after solid organ transplantion reflect the interplay between viral replication and CMV-specific immune reconstitution. Research in CMV-specific cell-mediated immunity paved way for the development of several laboratory assays that may assist clinicians in predicting the risk of CMV after transplantation, individualize the approach to CMV disease prevention, guide the need and duration of treatment of CMV infection, and predict the risk of relapse after treatment. More interventional studies are needed to further solidify the role of cell-mediated immune assays in various clinical situations after transplantation.

Immune Control of Human Cytomegalovirus (HCMV) Infection in HCMV-Seropositive Solid Organ Transplant Recipients: The Predictive Role of Different Immunological Assays

Human cytomegalovirus (HCMV) infection remains a major complication for solid organ transplant recipients (SOTRs). The aim of this study was to evaluate the role of HCMV-specific T cell immunity measured at the time of the HCMV-DNA peak in predicting the spontaneous clearance of infection. The performance of cytokine flow cytometry using infected dendritic cells (CFC-iDC), infected cell lysate (CFC-iCL) and pp65 peptide pool (CFC-pp65 pool) as stimuli, as well as ELISPOT assays using infected cell lysate (ELISPOT-iCL) and the pp65 peptide pool (ELISPOT-pp65 pool), was analysed. Among the 40 SOTRs enrolled, 16 patients (40%) required antiviral treatment for an HCMV infection (Non-Controllers), while the others spontaneously cleared the infection (Controllers). At the HCMV-DNA peak, the number of HCMV-specific CD4+ T cells detected by the CFC-iDC, CFC-iCL and CFC-pp65 pool assays in Controllers was higher than that detected in Non-Controllers, while no difference was observed in terms of HCMV-specific CD8+ T cell response. The same trend was observed when the HCMV-specific T cell response was measured by ELISPOT-iCL and ELISPOT-pp65 pool. We observed that the CD4+ CFC-pp65 pool assay was the best predictor of self-resolving HCMV infection at the time of the HCVM-DNA peak. The CFC-pp65 pool assay is able to discriminate between CD4+ and CD8+ T cell responses and could be used in daily clinical practice.

Real-World Experience With CMV inSIGHT T Cell Immunity Testing in High-Risk Kidney and Pancreas Transplant Recipients

BACKGROUND

Cytomegalovirus (CMV)-specific cell-mediated immunity is important for control of CMV after transplant. Assays exist to measure this, but their place in therapy is unclear, particularly in CMV high-risk recipients, without pretransplant exposure.

OBJECTIVE

The objective of this study was to evaluate predictive potential of a positive assay to determine freedom from DNAemia and describe subsequent 3-month CMV outcomes.

METHODS

Adult CMV high-risk kidney and/or pancreas transplant recipients were included if a CMV inSIGHT T Cell Immunity Panel (TCIP, Eurofins Viracor) was ordered and resulted between 1 August, 2019 and 30 July, 2022.

RESULTS

Seventy-six patients were included in our study; 49 tested during prophylaxis and 27 during treatment. Most TCIP assays obtained in the prophylaxis cohort were negative (n = 46, 93.9%). Rate of post-TCIP CMV infection was 10.2%. In those tested during treatment, 33.3% were positive and rate of post-TCIP CMV recurrence was 22.2%. The positive predictive value of the assay to successfully predict immunity was 66.7% during both prophylaxis and treatment. There were 4 cases of TCIP predictive failure with progressive CMV replication. At time of replication, 2 patients had concomitant clinical confounders thought to influence immune control of viral replication. All patients had intensification of immunosuppression prior to recurrent replication, but after TCIP was collected.

CONCLUSION AND RELEVANCE

The data obtained from the TCIP are not static, immune control of CMV in latency can change and must be evaluated in clinical context. Timing of TCIP after transplant is significant, and patient-specific factors remain important to assess the likelihood of CMV in each unique patient-specific scenario. A CMV stewardship program can aid in application and interpretation of results.

Cellular immunity against cytomegalovirus and risk of infection after kidney transplantation

Introduction

Cytomegalovirus (CMV) infection remains a challenge following kidney transplantation (KTx). Currently, CMV-IgG serostatus at transplantation is used to individualize CMV preventive strategies. We assessed the clinical utility of CMV-IGRA for predicting CMV infection following KTx.

Methods

We performed a nationwide prospective cohort study from August 2016 until December 2022. Data from all adult KTx recipients in Norway, n=1,546 (R+; n=1,157, D+/R-; n=260, D-/R-; 129), were included with a total of 3,556 CMV-IGRA analyses (1,375 at KTx, 1,188 at eight weeks, 993 one-year after KTx) and 35,782 CMV DNAemia analyses.

Results

In R+ recipients CMV-IGRA status, measured at any of the time-points, could not identify any differential risk of later CMV infection. D+/R- recipients remaining CMV-IGRA negative 1-year after transplantation (regardless of positive CMV DNAemia and/or CMV IgG status at that time) had increased risk of developing later CMV infection compared to D+/R- recipients who had become CMV-IGRA positive (14% vs. 2%, p=0.01).

Conclusion

Knowledge of pre-transplant CMV-IGRA status did not provide additional information to CMV-IgG serostatus that could improve current post-transplant CMV treatment algorithms. However, D+/R- recipients with a persisting negative CMV-IGRA one-year after transplantation remained at increased risk of experiencing later CMV infection. Therefore we advocate post-transplant CMV-IGRA monitoring in these patients.

QuantiFERON-CMV as a Predictor of CMV Events During Preemptive Therapy in CMV-seropositive Kidney Transplant Recipients

BACKGROUND

Prevention of cytomegalovirus (CMV) infection after kidney transplantation is costly and burdensome.

METHODS

Given its promising utility in risk stratification, we evaluated the use of QuantiFERON-CMV (QFCMV) and additional clinical variables in this prospective cohort study to predict the first clinically significant CMV infection (CS-CMV, ranging from asymptomatic viremia requiring treatment to CMV disease) in the first posttransplant year. A cost-effectiveness analysis for guided prevention was done.

RESULTS

One hundred adult kidney transplant recipients, CMV IgG + , were given basiliximab induction and maintained on steroid/mycophenolate/tacrolimus with weekly CMV monitoring. Thirty-nine patients developed CS-CMV infection (viral syndrome, n = 1; end-organ disease, n = 9; and asymptomatic viremia, n = 29). A nonreactive or indeterminate QFCMV result using the standard threshold around day 30 (but not before transplant) was associated with CS-CMV rates of 50% and 75%, respectively. A higher QFCMV threshold for reactivity (>1.0 IU interferon-γ/mL) outperformed the manufacturer's standard (>0.2 IU interferon-γ/mL) in predicting protection but still allowed a 16% incidence of CS-CMV. The combination of recipient age and type of donor, along with posttransplant QFCMV resulted in a prediction model that increased the negative predictive value from 84% (QFCMV alone) to 93%. QFCMV-guided preemptive therapy was of lower cost than preemptive therapy alone ( P  < 0.001, probabilistic sensitivity analysis) and was cost-effective (incremental net monetary benefit of 210 USD) assuming willingness-to-pay of 2000 USD to avoid 1 CMV disease.

CONCLUSIONS

Guided CMV prevention by the prediction model with QFCMV is cost-effective and would spare from CMV surveillance in 42% of patients with low risk for CS-CMV.

Using a commercially available assay that measures cytomegalovirus (CMV)-specific T-cell immunity to predict protection against CMV: A prospective, blinded clinical study

The Viracor CMV-T-cell immunity Panel (TCIP) measures %CMV-specific CD4+ and CD8+ T-cells. In this blinded clinical study, we evaluated the performance of the TCIP in predicting CMV events. Prospectively enrolled donor or recipient CMV-seropositive kidney transplant recipients (KTR) were evaluated with monthly TCIP testing until either discontinuation of valganciclovir prophylaxis or CMV DNAemia prompting treatment initiation. Also, prospectively enrolled KTR with low-level untreated DNAemia or after completion of treatment were evaluated for progression or relapse of CMV infection. Among 46 KTR, those with CMV events had significantly lower %CMV-specific CD8+ T-cells (p = 0.024), and the CMV protection ROC AUC was significant (AUC 0.78, p = 0.026). The positive predictive values of CD4+ and CD8+ T-cell positivity >0.2 % for CMV protection were: 96.3 % for CMV DNAemia prompting treatment initiation, 92.6 % for any DNAemia, 100 % for DNAemia >1000 IU/mL. The TCIP could be a useful adjunct tool in individualized management of CMV infection.

Performance Evaluation of Three Antibody Binding Assays, a Neutralizing Antibody Assay, and an Interferon-Gamma Release Assay for SARS-CoV-2 According to Vaccine Type in Vaccinated Group

We evaluated the performance of SARS-CoV-2 assays in the vaccinated group using receptor-binding domain antibody assays (RBD Ab assay), neutralizing antibody assay (nAb assay), and interferon-gamma release assay (IGR assay). We also compared the performance of the SARS-CoV-2 assays based on vaccine type in a large population. We collected 1851 samples from vaccinated individuals with vector, mix-and-match (MM), and mRNA vaccines. The performance of the RBD Ab assays was assessed by SARS-CoV-2 IgG II Quant (Abbott Laboratories, Sligo, Ireland), SARS-CoV-2 IgG (Beckman Coulter, CA, USA), and anti-SARS-CoV-2 S (Roche Diagnostics GmbH, Mannheim, Germany). The nAb assay was assessed by cPass SARS-CoV-2 neutralization antibody detection kits (GenScript, NJ, USA). The IGR assay was assessed by QuantiFERON (Qiagen, Venlo, The Netherlands). Median values of the RBD Ab assays and nAb assay sequentially increased after the first and second vaccinations. RBD Ab assays and nAb assay showed very strong correlations. The median values of the RBD Ab, nAb, and IGR were higher in the mRNA vaccine group than in the vector and MM vaccine groups. The agreement and correlation among the RBD Ab assays, nAb assay, and IGR assay were higher in the mRNA vaccine group than in the vector and MM vaccine groups. We compared the performance of the RBD Ab assay, nAb assay, and IGR assay based on the vaccine types using the RBD Ab, nAb, and IGR assays. This study provides a better understanding of the assessment of humoral and cellular immune responses after vaccination.

Herpes Virus Infection in Lung Transplantation: Diagnosis, Treatment and Prevention Strategies

Lung transplantation is an ultimate treatment option for some end-stage lung diseases; due to the intense immunosuppression needed to reduce the risk of developing acute and chronic allograft failure, infectious complications are highly incident. Viral infections represent nearly 30% of all infectious complications, with herpes viruses playing an important role in the development of acute and chronic diseases. Among them, cytomegalovirus (CMV) is a major cause of morbidity and mortality, being associated with an increased risk of chronic lung allograft failure. Epstein-Barr virus (EBV) is associated with transformation of infected B cells with the development of post-transplantation lymphoproliferative disorders (PTLDs). Similarly, herpes simplex virus (HSV), varicella zoster virus and human herpesviruses 6 and 7 can also be responsible for acute manifestations in lung transplant patients. During these last years, new, highly sensitive and specific diagnostic tests have been developed, and preventive and prophylactic strategies have been studied aiming to reduce and prevent the incidence of these viral infections. In this narrative review, we explore epidemiology, diagnosis and treatment options for more frequent herpes virus infections in lung transplant patients.

Cytomegalovirus Cell-Mediated Immunity: Ready for Routine Use?

Utilizing assays that assess specific T-cell-mediated immunity against cytomegalovirus (CMV) holds the potential to enhance personalized strategies aimed at preventing and treating CMV in organ transplantation. This includes improved risk stratification during transplantation compared to relying solely on CMV serostatus, as well as determining the optimal duration of antiviral prophylaxis, deciding on antiviral therapy when asymptomatic replication occurs, and estimating the risk of recurrence. In this review, we initially provide an overlook of the current concepts into the immune control of CMV after transplantation. We then summarize the existent literature on the clinical experience of the use of immune monitoring in organ transplantation, with a particular interest on the outcomes of interventional trials. Current evidence indicates that cell-mediated immune assays are helpful in identifying patients at low risk for replication for whom preventive measures against CMV can be safely withheld. As more data accumulates from these and other clinical scenarios, it is foreseeable that these assays will likely become part of the routine clinical practice in organ transplantation.

A Systematic Review and Meta-analysis of Optimized CMV Preemptive Therapy and Antiviral Prophylaxis for CMV Disease Prevention in CMV High-Risk (D+R-) Kidney Transplant Recipients

The optimal strategy for cytomegalovirus (CMV) disease prevention in CMV donor/recipient kidney transplant recipients remains uncertain. Conclusions of prior meta-analyses that CMV disease rates with preemptive therapy (PET) and universal prophylaxis (UP) were comparable may have been affected by inclusion of studies lacking key determinants of efficacy of the respective strategies.

Methods

We conducted a systematic review and meta-analysis of PET with weekly CMV polymerase chain reaction monitoring for ≥3 mo and UP with 6 mo of valganciclovir. PubMed and Embase databases were reviewed from January 1, 2010, to April 1, 2022. Risk of bias was assessed with 3 instruments (Cochrane RoB, Cochrane RoBINS-I, and an instrument for assessing risk in observational studies). The primary outcome was CMV disease incidence by 1-y posttransplant. Secondary outcomes by 1-y were graft loss, acute allograft rejection, and mortality. Results were synthesized using generalized linear mixed model meta-analysis. PET studies were stratified into low-threshold (LT) and high-threshold (HT) PET based on the viral load threshold for initiation of antiviral therapy.

Results

Twenty-five studies met inclusion criteria (6 PET, 19 UP). CMV disease incidence was significantly higher in HT (0.30 [95% confidence interval (CI), 0.22-0.39]) versus LT PET (0.06 [95% CI, 0.03-0.12]). LT PET was associated with a significantly lower CMV disease incidence (0.06 [95% CI, 0.03-0.12]) versus UP (0.21 [95% CI, 0.17-0.27]). Incidence of graft loss, acute allograft rejection, or mortality was not significantly different between LT PET and UP (P > 0.05 for all comparisons). Receipt of lymphocyte-depleting antibodies was not associated with a significant difference in CMV disease incidence (odds ratio = 1.34 [95% CI, 0.80-2.25]).

Conclusions

LT PET is associated with a significantly lower incidence of CMV disease compared to UP with similar rates of other clinical outcomes. These findings provide rationale and preliminary data for a randomized superiority trial of optimized LT-PET versus UP in donor seropositive recipient seronegative kidney transplant recipients.

Contemporary Biomarkers for Renal Transplantation: A Narrative Overview

Renal transplantation (RT) is the preferred treatment for end-stage renal disease. However, clinical challenges persist, i.e., early detection of graft dysfunction, timely identification of rejection episodes, personalization of immunosuppressive therapy, and prediction of long-term graft survival. Biomarkers have emerged as valuable tools to address these challenges and revolutionize RT patient care. Our review synthesizes the existing scientific literature to highlight promising biomarkers, their biological characteristics, and their potential roles in enhancing clinical decision-making and patient outcomes. Emerging non-invasive biomarkers seemingly provide valuable insights into the immunopathology of nephron injury and allograft rejection. Moreover, we analyzed biomarkers with intra-nephron specificities, i.e., glomerular vs. tubular (proximal vs. distal), which can localize an injury in different nephron areas. Additionally, this paper provides a comprehensive analysis of the potential clinical applications of biomarkers in the prediction, detection, differential diagnosis and assessment of post-RT non-surgical allograft complications. Lastly, we focus on the pursuit of immune tolerance biomarkers, which aims to reclassify transplant recipients based on immune risk thresholds, guide personalized immunosuppression strategies, and ultimately identify patients for whom immunosuppression may safely be reduced. Further research, validation, standardization, and prospective studies are necessary to fully harness the clinical utility of RT biomarkers and guide the development of targeted therapies.

Torque teno virus viremia and QuantiFERON®-CMV assay in prediction of cytomegalovirus reactivation in R+ kidney transplant recipients

Introduction

Cytomegalovirus (CMV) is the most frequent infectious complication following solid organ transplantation. Torque teno viruses (TTV) viremia has been proposed as a biomarker of functional immunity in the management of kidney transplant recipients (KTR). The QuantiFERON^®-CMV (QF-CMV) is a commercially available assay that allows the assessment of CD8⁺ T-cell responses in routine diagnostic laboratories.

Methods

In a prospective national multicenter cohort of 64 CMV-seropositive (R+) KTR, we analyzed the value of TTV load and the two markers of the QF-CMV assay [QF-Ag (CMV-specific T-cell responses) and QF-Mg (overall T-cell responses)], alone and in combination, in prediction of CMV reactivation (≥3 log₁₀ IU/ ml) in the first post-transplant year. We compared previously published cut-offs and specific cut-offs optimized from ROC curves for our population.

Results

Using the conventional cut-off (3.45 log₁₀ copies/ml), TTV load at D0 [inclusion visit on the day of transplantation before induction (D0)], or at M1 (1-month post-transplant visit) perform better in predicting CMV viremia control than CMV reactivation. Survival analyses suggest a better performance of our optimized TTV cut-offs (3.78 log₁₀ copies/ml at D0 and 4.23 log₁₀ copies/ml at M1) for risk stratification of CMV reactivation in our R+ KTR cohort. The QF-CMV (QF-Ag = 0.2 IU/ml, and QF-Mg = 0.5 IU/ml) also appears to better predict CMV viremia control than CMV reactivation. Moreover, survival analyses suggest that the QF-Mg would perform better than the QF-Ag in stratifying the risk of CMV reactivation. The use of our optimized QF-Mg cut-off (1.27 IU/ml) at M1 further improved risk stratification of CMV reactivation. Using conventional cut-offs, the combination of TTV load and QF-Ag or TTV load and QF-Mg did not improve prediction of CMV viremia control compared to separate analysis of each marker but resulted in an increase of positive predictive values. The use of our cut-offs slightly improved risk prediction of CMV reactivation.

Conclusion

The combination of TTV load and QF-Ag or TTV load and QF-Mg could be useful in stratifying the risk of CMV reactivation in R+ KTR during the first post-transplant year and thereby have an impact on the duration of prophylaxis in these patients.

Clinical trial registration

ClinicalTrials.gov registry, identifier NCT02064699.

Immunological monitoring after allogeneic stem cell transplantation: T-SPOT.CMV and QuantiFERON-CMV, are they the same?

BACKGROUND

CMV-reactivation and -disease is still a major concern after allogeneic stem cell transplantation [allo-HSCT], despite prophylactic and pre-emptive strategies. In recent years, immunologic monitoring using CMV-IGRA has gained interest to better risk stratify immunocompromised patients or to guide prophylactic therapies. CMV-IGRA can quantify CMV cell-mediated immunity by measuring the interferon-gamma that is released by CD4+ and CD8+ T-lymphocytes in the presence of CMV-antigens. However, the two most widely used CMV-IGRAs, T-SPOT.CMV and QuantiFERON-CMV, have not yet been compared in the setting of an allo-HSCT.

OBJECTIVE

To perform a method comparison between the T-SPOT.CMV and QuantiFERON-CMV 28 and 100 days after allo-HSCT, and to assess predictive values of both tests for CMV-reactivation.

STUDY DESIGN

In a bicentric prospective trial, 27 patients were included. Samples were taken on day +28 and day +100 after allo-HSCT. Patients' clinical information was collected up to 270 days after the transplant. Method comparison was performed using Cohen's kappa.

RESULTS

On day +28 (n=26) after allo-HSCT T-SPOT.CMV gave three positive test results, and QuantiFERON-CMV only two. On day +100 (n=24) T-SPOT.CMV gave seven positive test results, and QuantiFERON-CMV nine. One discordant result was obtained at day +28 (n=26), while six results were discordant at day +100 (n=24). Method comparison showed a strong agreement on day +28 (κ = 0.780 [95% CI: 0.366-1.000]), but only a moderate agreement on day +100 (κ = 0.442 [95% CI: 0.070-0.814]) and on pooled data from both time points (κ = 0.578 [95% CI: 0.300-0.856]). Four clinically significant CMV infections, (CS-CMVi) were observed, all occurring after discontinuation of letermovir-prophylaxis. None of those four patients had a positive result with either test at day +100 (or day +28). Negative predictive values (NPV) and sensitivity are therefore very high at 100% (for both tests, for NPV and sensitivity, measured at day +100). At day+100, positive predictive values (PPV) and specificity were considerably lower (T-SPOT.CMV: PPV 23.5% and specificity 35% - QuantiFERON-CMV: PPV 26.7% and specificity 45%).

CONCLUSION

T-SPOT.CMV and QuantiFERON-CMV only have a moderate agreement (at day +100) after allo-HSCT. Although these IGRAs are very promising, as shown by their very high negative predictive values for protection against CS-CMVi, they are not interchangeable. Future research should stipulate which IGRA was used, and future guidelines should preferably be assay-specific. As the QuantiFERON-CMV to date still lacks a large validation study after allo-HSCT, the moderate agreement with the T-SPOT.CMV poses a significant hurdle in the routine implementation of this test.

Cytomegalovirus Specific Cell-Mediated Immunity Status in Women with Preeclampsia: A Case-Control Study

Background

Preeclampsia, a pregnancy-specific complication, has been associated with cytomegalovirus (CMV) infection in observational studies. CMV-specific T cell response plays a major role in viremia clearance. We explored whether CMV-specific cell-mediated immunity (CMI) status is associated with preeclampsia in pregnant women.

Materials and Methods

CMV-specific CMI was assessed using CMV-QuantiFERON (QF-CMV) assay in plasma serum of 35 women with preeclampsia as well as 35 normal pregnant controls, retrospectively. Participants were matched for gestational age in a 1:1 ratio. The proportion of reactive results, the mean value of interferon-gamma (IFN-γ) level produced in mitogen and antigen tubes were compared between the cases and controls through Chi-square and Wilcoxon rank-sum tests, respectively. The odds ratio and confidence interval were calculated as well.

Results

No significant differences observed between demographic characteristics of the case and control groups. The QF-CMV assay turned reactive (QF-CMV [ + ]) Women with preeclampsia had lower mean IFN-γ levels in antigen tube compared with normal pregnant controls. There were no statistically significant differences in the value of mitogen tube between case and controls women with suppressed CMV-CMI were 6.3 times more likely to have preeclampsia. This result even strengthened after adjustment for age, gestational age, and gravidity.

Conclusions

Our findings support an association between suppressed CMV-specific CMI and preeclampsia.

Four-Year Follow-Up of the Maternal Immunological, Virological and Clinical Settings of a 36-Year-Old Woman Experiencing Primary Cytomegalovirus Infection Leading to Intrauterine Infection

The present study aims to provide the sequential immunological, clinical and virological events occurring in a CMV-infected pregnant woman experiencing intrauterine CMV transmission. In brief, a case of primary CMV infection occurred in a 36-year-old pregnant woman. The patient exhibited early-sustained viremia and viruria, detectable presence of CMV in saliva concomitant with a strong CMV-specific cell-mediated response (427 EliSpots). CMV was detected in the amniotic fluid at 15 weeks of pregnancy (>1 × 106 CMV copies/mL). The pregnancy was deliberately interrupted at 16 weeks of gestation. Fetal histological and pathological examinations revealed placentitis and fetal brain alterations as microcephaly and cortical dysplasia. Interestingly, this clinical report shows: (1) there was a rapid and sustained CMV-specific cell mediated immune response (Th1) in association with low IgG avidity (Th2) correlated with fetal CMV transmission. (2) The levels of CMV-specific cell-mediated immune response persisted at high levels up to 200 weeks after infection despite clinical and viral clearance. (3) The histological and pathological evidence suggests that a potent pro-inflammatory condition at the placental level may lead to cCMV.

A consensus conference to define the utility of advanced infectious disease diagnostics in solid organ transplant recipients

The last decade has seen an explosion of advanced assays for the diagnosis of infectious diseases, yet evidence-based recommendations to inform their optimal use in the care of transplant recipients are lacking. A consensus conference sponsored by the American Society of Transplantation (AST) was convened on December 7, 2021, to define the utility of novel infectious disease diagnostics in organ transplant recipients. The conference represented a collaborative effort by experts in transplant infectious diseases, diagnostic stewardship, and clinical microbiology from centers across North America to evaluate current uses, unmet needs, and future directions for assays in 5 categories including (1) multiplex molecular assays, (2) rapid antimicrobial resistance detection methods, (3) pathogen-specific T-cell reactivity assays, (4) next-generation sequencing assays, and (5) mass spectrometry-based assays. Participants reviewed and appraised available literature, determined assay advantages and limitations, developed best practice guidance largely based on expert opinion for clinical use, and identified areas of future investigation in the setting of transplantation. In addition, attendees emphasized the need for well-designed studies to generate high-quality evidence needed to guide care, identified regulatory and financial barriers, and discussed the role of regulatory agencies in facilitating research and implementation of these assays. Findings and consensus statements are presented.

QuantiFERON-Cytomegalovirus Assay for Prediction of Cytomegalovirus Viremia in Kidney Transplant Recipients: Study From High Cytomegalovirus Seroprevalence Country

Background

Early studies showed the utility of pretransplant QuantiFERON-Cytomegalovirus (QF-CMV) assays for CMV-disease prediction post kidney transplant (KT). However, recent data are conflicting.

Methods

This prospective cohort study enrolled adult patients undergoing KT between July 2017 and May 2019. Patients with antithymocyte globulin therapy or negative pretransplant CMV IgG were excluded. QF-CMV assays were performed on transplantation day and one month thereafter, and CMV viral loads were obtained 1, 3, and 6 months posttransplantation. The primary outcome was CMV viremia within 6 months. The QF-CMV assay–posttransplant CMV viremia association was analyzed.

Results

Fifty-five patients were enrolled (male, 58.2%; mean (SD) age, 46.5 (10.2) years). Fifty-two (94.5%) received CMV-seropositive donor kidneys. Over 6 months, 29 patients developed CMV viremia (52.7%), with 14 (25.5%) having significant viremia requiring antiviral therapy. The CMV-viremia incidence of patients with nonreactive and reactive baseline QF-CMV assays did not differ significantly (55.3% and 47.1%; p = 0.573). Among patients with reactive pretransplant QF-CMV assays, there was a trend toward a lower incidence of CMV viremia for those who were persistently reactive at 1 month after KTs, although there was no statistically significant difference (50% vs 83%; p = 0.132).

Conclusions

Our study could not support the use of single-timepoint pretransplant or 1-month posttransplant QF-CMV assays as a predictor for posttransplant CMV viremia in CMV seropositive KT recipients. Investigation of the association between dynamic QF-CMV-status changes and CMV-viremia incidence are needed.

Laboratory diagnostic testing for cytomegalovirus infection in solid organ transplant patients

Human cytomegalovirus (CMV) infection, which is one of the most common complications in transplant recipients, increases the risk of graft loss and rejection. Laboratory strategies for diagnosing CMV infection rely on the measurement of viral DNAemia and CMV-specific cell-mediated immunity (CMV-CMI). The CMV quantitative nucleic acid amplification test (QNAT) enabled the spread of preemptive therapy and prompted recommendations for surveillance, diagnosis, and monitoring. Despite the implementation of the World Health Organization international standard for calibration, variability of QNAT persists due to technical issues. CMV immunoglobulin G serology is the standard method for CMV immune screening of transplant candidates and donors. Assays for CMV-CMI play an important role in helping to predict the risk and to develop an individualized CMV management plan. Genotypic testing for resistance is needed when drug-resistant CMV infection is suspected. Here, we review the state of the art of laboratory tests for CMV infection in solid organ transplantation.

Negative immune responses to two-dose mRNA COVID-19 vaccines in renal allograft recipients assessed with simple antibody and interferon gamma release assay cellular monitoring

Studies are urgently needed to characterize immunogenicity, efficacy, and safety of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines in kidney transplant (KT) recipients, excluded from major clinical trials. Complex ELISPOT and other cellular response techniques have been applied, but simpler tools are needed. An easy-to-use real-world monitoring of SARS-CoV-2 IgG antibodies against the Spike protein and QuantiFERON^® SARS-CoV-2 IFNγ release assay (IGRA) were performed at baseline and 28 days after the second dose in KT recipients and controls (dialysis patients and healthy ones). All healthy controls and >95% dialysis controls became positive for anti-S IgG antibodies, while only 63.3% of KT patients seroconverted with a very low antibody level. A positive IGRA was documented in 96.9% of controls, 89.3% peritoneal dialysis, 77.6% hemodialysis, 61.3% of KT patients transplanted more than 1 year ago and only 36% of those transplanted within the previous 12 months. Overall, 100% of healthy controls, 95.4% of dialysis patients and 78.8% KT recipients developed any immune response (humoral and/or cellular) against SARS-CoV-2. KT patients showed low rates of immune responses to mRNA Coronavirus infectious disease 2019 vaccines, especially those with recent transplantations. Simple humoral and cellular monitoring is advisable, so that repeated doses may be scheduled according to the results.

Efficacy and Safety According to the Dose of Valganciclovir for Cytomegalovirus Prophylaxis in Transplantation: Network Meta-analysis Using Recent Data

BACKGROUND

Valganciclovir is used to prevent posttransplant cytomegalovirus (CMV) infection among patients undergoing kidney transplant. However, the optimal dose remains controversial because continuous use decreases kidney function and can induce leukopenia. The purpose of this study was to identify the appropriate dose of valganciclovir for preventing CMV using network meta-analysis.

METHODS

We searched the Cochrane Central Register, Ovid MEDLINE, EMBASE, Cumulative Index to Nursing and Allied Health, and Web of Science databases for studies published through April 15, 2017, evaluating 900-mg and 450-mg valganciclovir. We performed direct and indirect network meta-analysis using Bayesian models and generated rankings of different doses of valganciclovir by generating a mixed-treatment comparison.

RESULTS

Twenty-three studies involving 3478 participants were included. Compared with the control group, there was no difference in the incidence of CMV infection between the low-dose (450 mg) (odds ratio [OR], 0.79; 95% confidence interval [CI], 0.50-1.40) and high-dose (900 mg) (OR, 1.0; 95% CI, 0.61-1.60) groups. Low-dose valganciclovir had the best probability (71.1%) for decreasing CMV infection. Leukopenia was significantly more common in the high-dose group than in the control group (OR, 4.3; 95% CI, 2.69-7.10) and in the low-dose group (OR, 2.9; 95% CI, 1.88-4.67), but there was no significant difference in the incidence of leukopenia between the low-dose and control groups (OR, 1.5; 95% CI, 0.99-2.20).

CONCLUSIONS

The incidence of CMV was not different based on the dose of valganciclovir, although the tendency for CMV infection was decreased at 450 mg. However, the low dose of valganciclovir significantly reduced the incidence of leukopenia.

Utility of CMV-Specific Immune Monitoring for the Management of CMV in Solid Organ Transplant Recipients: A Clinical Update

Cytomegalovirus (CMV) is one of the most important opportunistic infections in solid organ transplant (SOT) recipients. However, current techniques used to predict risk for CMV infection fall short. CMV-specific cell mediated immunity (CMI) plays an important role in protecting against CMV infection. There is evidence that assays measuring CMV-CMI might better identify SOT recipients at risk of complications from CMV compared to anti-CMV IgG, which is our current standard of care. Here, we review recently published studies that utilize CMV-CMI, at various points before and after transplantation, to help predict risk and guide the management of CMV infection following organ transplantation. The evidence supports the use of these novel assays to help identify SOT recipients at increased risk and highlights the need for larger prospective trials evaluating these modalities in this high-risk population.

Pre-existing T-cell immunity to SARS-CoV-2 in unexposed healthy controls in Ecuador, as detected with a COVID-19 Interferon-Gamma Release Assay

BACKGROUND

Studies of T-cell immune responses against SARS-CoV-2 are important in understanding the immune status of individuals or populations. Here, we use a simple, cheap, and rapid whole blood stimulation assay - an Interferon-Gamma Release Assay (IGRA) - to study T-cell immunity to SARS-CoV-2 in convalescent COVID-19 patients and in unexposed healthy contacts from Quito, Ecuador.

METHODS

Interferon-gamma (INF-γ) production was measured in the heparinized blood of convalescent and unexposed subjects after stimulation for 24 h with the SARS-CoV-2 Spike S1 protein, the Receptor Binding Domain (RBD) protein or the Nucleocapsid (NP) protein, respectively. The presence of IgG-RBD protein antibodies in both study groups was determined with an "in-house" ELISA.

RESULTS

As measured with INF-γ production, 80% of the convalescent COVID-19 patients, all IgG-RBD seropositive, had a strong T-cell response. However, unexpectedly, 44% of unexposed healthy controls, all IgG-RBD seronegative, had a strong virus-specific T-cell response with the COVID-19 IGRA, probably because of prior exposure to common cold-causing coronaviruses or other viral or microbial antigens.

CONCLUSION AND DISCUSSION

The high percentage of unexposed healthy subjects with a pre-existing immunity suggests that a part of the Ecuadorian population is likely to have SARS-CoV-2 reactive T-cells. Given that the IGRA technique is simple and can be easily scaled up for investigations where high numbers of patients are needed, this COVID-19 IGRA may serve to determine if the T-cell only response represents protective immunity to SARS-CoV-2 infection in a population-based study.

T-Cell Immune Surveillance in Allogenic Stem Cell Transplant Recipients: Are Whole Blood-Based Assays Ready to Challenge ELISPOT?

We compared the feasibility of 4 cytomegalovirus (CMV)- and Aspergillus-reactive T-cell immunoassay protocols in allogenic stem cell transplant recipients. While enzyme-linked immunospot performed best overall, logistically advantageous whole blood–based assays performed comparably in patients with less severe lymphocytopenia. CMV-induced interferon-gamma responses correlated strongly across all protocols and showed high concordance with serology.

A split strategy to prevent cytomegalovirus after kidney transplantation using prophylaxis in serological high-risk patients and a pre-emptive strategy in intermediate-risk patients: Combining the best of two options?

BACKGROUND

Cytomegalovirus (CMV) remains an important challenge after kidney transplantation. Current Transplantation Society International Consensus Guidelines recommend antiviral prophylaxis or pre-emptive therapy for high-risk CMV-seronegative recipients with a CMV-seropositive donor (D+/R-) and moderate-risk CMV-seropositive recipients (R+). However, a split strategy according to CMV serostatus is not specifically mentioned.

METHODS

We evaluated a split strategy to prevent CMV infection after kidney transplantation in which D+/R- patients received valganciclovir (VGC) prophylaxis for 200 days, and R + patients were treated pre-emptively according to CMV DNAemia. Patients were followed until 1-year post-transplant.

RESULTS

Between April 2014 and March 2018, 40 D+/R- and 92 R + patients underwent kidney transplantation. Forty-six percent received antithymocyte globulin (ATG) induction, and 98% was treated with calcineurin inhibitors, mycophenolic acid (MPA), and steroids. No D+/R- patient developed CMV disease during prophylaxis (median 200 days), but 15% developed post-prophylaxis or late-onset disease. Fifty-three percent developed neutropenia during prophylaxis, including 16/40 (40%) grade 3 or 4 neutropenia requiring reduction/discontinuation of MPA (30%) and/or VGC (35%), and an occasional need for granulocyte colony-stimulating factor (5%). In the R + group, 40% received antiviral therapy for a median duration of 21 days; 5% developed early-onset CMV disease. Only 5% developed neutropenia. D+/R + status (hazard ratio (HR) 2.09,P = .004) and ATG use (HR 2.81, P < .0001) were risk factors for CMV reactivation.

CONCLUSIONS

Prophylaxis leads to acceptable CMV control in high-risk patients but comes with a high risk of neutropenia. Pre-emptive therapy is effective and limits drug exposure in those at lower risk of CMV.

Monitoring of CMV-specific cell-mediated immunity with a commercial ELISA-based interferon-γ release assay in kidney transplant recipients treated with antithymocyte globulin

Monitoring for cytomegalovirus (CMV)-specific cell-mediated immunity (CMV-CMI) may be useful for individualizing valganciclovir (VGCV) prophylaxis after kidney transplantation (KT). We performed a commercial ELISA-based interferon (IFN)-γ release assay (QTF-CMV) from posttransplant months 2-5 (362 points) in 120 CMV-seropositive KT recipients that received antithymocyte globulin as induction therapy and VGCV prophylaxis (median of 92 days). Forty-seven patients (39.3%) had CMV infection after discontinuation of prophylaxis. The QTF-CMV assay was reactive, nonreactive, and indeterminate in 264 (72.9%), 90 (24.9%), and 8 points (2.2%). The QTF-CMV assay at prophylaxis discontinuation exhibited suboptimal accuracy for predicting protective CMV-CMI (sensitivity: 77.4%; specificity: 34.3%; positive predictive value [PPV]: 64.1%; negative predictive value [NPV]: 50.0%), with no differences in 1-year CMV infection rates between patients with negative (nonreactive or indeterminate) or reactive results (45.8% vs 36.1%; P = .244). Specificity and PPV to predict protective CMV-CMI improved by elevating the IFN-γ cutoff value to 1.13 IU/mL (65.7% and 71.4%) and 7.0 IU/mL (85.7% and 76.2%), although NPVs decreased. The QTF-CMV assay as per manufacturer's interpretative criteria performed poorly to predict protection from CMV infection following discontinuation of VGCV prophylaxis among ATG-treated CMV-seropositive KT recipients. This performance is slightly improved by modifying the IFN-γ positivity threshold.

Prediction of cytomegalovirus infection: A single-center experience utilizing a newly available cell-mediated immunity assay by flow cytometry, a risk factor screening tool, and serologically demonstrated immunity

PURPOSE

Describe use and predictive potential of an intracellular cytokine staining (ICS) cytomegalovirus cell-mediated immunity (CMV CMI) assay and a risk factor screening tool on CMV reactivation in a real-world clinical setting and compare this to serologically demonstrated immunity by CMV IGG.

METHODS

Adult transplant patients at our center with the ICS assay resulted between 10/1/2018 and 9/1/2019 were included. Assays were considered positive per manufacturer specifications.

RESULTS

Twenty-five patients underwent ICS CMV CMI testing at our institution during the study period. The majority were kidney transplant recipients, 76% were D+/R-, and 76% were receiving CMV treatment. The positive predictive value (PPV) of the assay to predict lack of CMV was 87%; 93% when patients with antiviral resistance were excluded and 91% in only those receiving treatment. The presence of ≤2 clinical risk factors on the screening tool had a PPV of 92% in predicting lack of recurrence. In comparison, serologically demonstrated immunity by CMV IGG had a PPV of 62%.

CONCLUSIONS

In our study representing real-world clinical use, the ICS CMV CMI assay and the risk factor screening tool had predictive potential that was superior to serologically demonstrated immunity. The reliability of the assay seemed to decrease with higher degrees of clinical risk suggesting a multimodal screening approach is warranted.

[Functional immunoassays in the setting of infectious risk and immunosuppressive therapy of non-HIV immunocompromised patients]

The holistic approach of the human immune system is based on the study of its components collectively driving a functional response to an immunogenic stimulus. To appreciate a specific immune dysfunction, a condition is mimicked ex vivo and the immune response induced is assessed. The application field of such assays are broad and expanding, from the diagnosis of primary and secondary immunodeficiencies, immunotherapy for cancer to the management of patients at-risk for infections and vaccination. These assays are immune monitoring tools that may contribute to a personalised and precision medicine. The purpose of this review is to describe immune functional assays available in the setting of non-HIV acquired immune deficiency. First, we will address the use of theses assays in the diagnosis of opportunistic infections such as viral reactivation. Secondly, we will report the usefulness of these assays to assess vaccine efficacy and to manage immunosuppressive therapies.

The development and implementation of stewardship initiatives to optimize the prevention and treatment of cytomegalovirus infection in solid-organ transplant recipients

Classical stewardship efforts have targeted immunocompetent patients; however, appropriate use of antimicrobials in the immunocompromised host has become a target of interest. Cytomegalovirus (CMV) infection is one of the most common and significant complications after solid-organ transplant (SOT). The treatment of CMV requires a dual approach of antiviral drug therapy and reduction of immunosuppression for optimal outcomes. This dual approach to CMV management increases complexity and requires individualization of therapy to balance antiviral efficacy with the risk of allograft rejection. In this review, we focus on the development and implementation of CMV stewardship initiatives, as a component of antimicrobial stewardship in the immunocompromised host, to optimize the management of prevention and treatment of CMV in SOT recipients. These initiatives have the potential not only to improve judicious use of antivirals and prevent resistance but also to improve patient and graft survival given the interconnection between CMV infection and allograft function.

Lack of cytomegalovirus (CMV)-specific cell-mediated immune response using QuantiFERON-CMV assay in CMV-seropositive healthy volunteers: fact not artifact

The QuantiFERON-CMV (QF) assay measures cell-mediated immunity against cytomegalovirus (CMV-CMI), which is particularly useful in individuals susceptible to CMV infection such as transplant patients. A positive QF result identifies patients that are better protected against CMV infection. However, the significance of a negative QF result in CMV-seropositive individuals needs to be clarified. CMV-CMI was analyzed in healthy subjects using the QF assay, and, in parallel, the Flow-cytometric Assay of Specific Cell-mediated Immune response in Activated whole blood (FASCIA). FASCIA assay measures T-cell proliferation using CMV lysate as stimulus whereas QF assay use a mix of peptides. A total of 93 healthy volunteers were enrolled, and 13/71 CMV-seropositive individuals (18.3%) showed humoral/cellular discordance using QF assay (CMV+ QF-). Interestingly, with FASCIA assay CD4+ and CD8+ T-cell proliferations were lower in CMV+ QF- than in CMV+ QF+ individuals. Furthermore, CMV+ QF- volunteers had a lower level of anti-CMV IgG than CMV+ QF+ subjects. Discordant CMV+ QF- volunteers can be defined as low responder individuals since they show lower CMV-specific humoral and cellular immune responses in comparison to CMV+ QF+ individuals. Immune discordance shows the high heterogeneity of immunity to CMV in healthy subjects.

Low-level positive results in the Liaison CMV IgG II assay may misclassify pregnant woman as immune

The aim of this study is to report on the specificity in the low-positive range of the Liaison CMV IgG II assay for determination of cytomegalovirus immune status in pregnancy. Sera with test results between 12.0 and 40.0 U/mL were retested with the Enzygnost Anti-CMV/IgG assay. Enzygnost-negative samples were analyzed by the Serion ELISA classic Cytomegalovirus IgG assay and, if positive or equivocal, also with the Mikrogen recomLine CMV IgG assay. A total of 12,117 sera were tested with the Liaison assay. Sixty sera were equivocal (12.0-13.9 U/mL), and 400 of 4295 positive sera were low-positive (14.0-40.0 U/mL). Based on consensus, at least 14% of the low-positives and 1.3% of all Liaison-positives can be considered as misclassified. The proportion of misclassified sera increased with lower Liaison IgG results. We suggest that the range for equivocal results in the Liaison assay should be revised.

Diagnostic usefulness of the cytomegalovirus (CMV)-specific T cell-based assay for predicting CMV infection after kidney transplant

BACKGROUND/AIMS

We evaluated the usefulness in kidney transplant (KT) candidates of cytomegalovirus (CMV)-specific enzyme-linked immunospot (ELISPOT) assays for predicting the development of post-transplant CMV infections.

METHODS

All adult recipients admitted for living-donor KT between March 2014 and March 2015 were prospectively enrolled except donor CMV-seropositive and recipient seronegative (D+/R-) recipients. All the enrolled patients underwent CMV-specific ELISPOT assays before transplant, and a researcher blinded to the results of these assays examined the patients for CMV infection at least 6 months post-transplant.

RESULTS

Of 133 KT recipients, 44 (33%) developed CMV infections. When we used the cut-off determined by receiver operator characteristic curve, 16 of the 34 patients (47%) with negative pp65-specific ELISPOT results (< 11 spots/200,000 cells) developed CMV infections, whereas 28 of the 99 patients (39%) with positive pp65-specific ELISPOT results at baseline (≥ 11 spots/200,000 cells) developed CMV infections after KT (p = 0.02). Based on the multivariable Cox regression model, negative pp65-specific ELISPOT assay results was an independent risk factor for CMV infection (adjusted hazard ratio [AHR], 1.87; 95% confidence interval [CI], 1.01 to 3.46; p = 0.047) as well as age (AHR, 1.05; 95% CI, 1.01 to 1.08; p = 0.007).

CONCLUSION

Pre-transplant CMV-specific ELISPOT assay appears to predict the development of CMV infections after KT in recipients at moderate risk such as CMV-seropositive recipients (Clinical Trial Registration Number NCT02025335).

Clinical experience with a novel assay measuring cytomegalovirus (CMV)-specific CD4+ and CD8+ T-cell immunity by flow cytometry and intracellular cytokine staining to predict clinically significant CMV events

BACKGROUND

Cytomegalovirus (CMV) infection is one of the most common opportunistic infections following organ transplantation, despite administration of CMV prophylaxis. CMV-specific T-cell immunity (TCI) has been associated with reduced rates of CMV infection. We describe for the first time clinical experience using the CMV T-Cell Immunity Panel (CMV-TCIP), a commercially available assay which measures CMV-specific CD4+ and CD8+ T-cell responses, to predict clinically significant CMV events.

METHODS

Adult (> 18-year-old) patients with CMV-TCIP results and ≥ 1 subsequent assessment for CMV DNAemia were included at Brown University and the University of Maryland Medical Center-affiliated hospitals between 4/2017 and 5/2019. A clinically significant CMV event was defined as CMV DNAemia prompting initiation of treatment. We excluded indeterminate results, mostly due to background positivity, allogeneic hematopoetic cell transplant (HCT) recipients, or patients who were continued on antiviral therapy against CMV irrespective of the CMV-TCIP result, because ongoing antiviral therapy could prevent a CMV event.

RESULTS

We analyzed 44 samples from 37 patients: 31 were solid organ transplant recipients, 4 had hematologic malignancies, 2 had autoimmune disorders. The CMV-protection receiver operating characteristic (ROC) area under the curve (AUC) was significant for %CMV-specific CD4+ (AUC: 0.78, P < 0.001) and borderline for CD8+ (AUC: 0.66, P = 0.064) T-cells. At a cut-off value of 0.22% CMV-specific CD4+ T-cells, positive predictive value (PPV) for protection against CMV was 85% (95%CI 65-96%), and negative predictive value (NPV) was 67% (95%CI 41-87%).

CONCLUSIONS

The CMV-TCIP, in particular %CMV-specific CD4+ T-cells, showed good diagnostic performance to predict CMV events. The CMV-TCIP may be a useful test in clinical practice, and merits further validation in larger prospective studies.

Cytomegalovirus-specific CD8+ T-cell responses are associated with arterial blood pressure in people living with HIV

People living with HIV (PLHIV) are at increased risk for cardiovascular disease (CVD), and immunity against cytomegalovirus (CMV) may be a contributing factor. We hypothesized that enhanced T-cell responses against CMV and CMV-IgG antibody-levels are associated with higher arterial blood pressure in PLHIV. We assessed serum CMV-IgG, systolic- (SBP) and diastolic- (DBP) blood pressure, pulse pressure (PP), traditional risk factors, activated CD8+ T-cells (CD38+HLA-DR+), senescent CD8+ T-cells (CD28-CD57+) and interleukin-6 (IL-6) in 60 PLHIV and 31 HIV-uninfected controls matched on age, gender, education and comorbidity. In PLHIV, expression of interleukin-2, tumor necrosis factor-α and interferon-γ was measured by intracellular-cytokine-staining after stimulation of T-cells with CMV-pp65 and CMV-gB. Associations between CMV-specific immune responses and hypertension, SBP, DBP or PP were assessed by multivariate logistic and linear regression models adjusted for appropriate confounders. The median age of PLHIV was 47 years and 90% were male. Prevalence of hypertension in PLHIV was 37% compared to 55% of HIV-uninfected controls. CMV-specific CD8+ T-cell responses were independently associated with higher PP (CMV-pp65; β = 2.29, p = 0.001, CMV-gB; β = 2.42, p = 0.001) in PLHIV. No significant differences were found with regard to individual measures of SBP and DBP. A possible weak association was found between CMV-IgG and hypertension (β = 1.33, p = 0.049) after adjustment for age, smoking and LDL-cholesterol. HIV-related factors, IL-6, CD8+ T-cell activation or CD8+ T-cell senescence did not mediate the associations, and no associations were found between CMV-specific CD4+ T-cell responses and blood pressure in PLHIV. In conclusion, increased arterial blood pressure in PLHIV may be affected by heightened CMV-specific CD8+ T-cell responses.

Monitoring of CMV-Specific Cell-Mediated Immunity in Kidney Transplant Recipients With a High Risk of CMV Disease (D+/R-): A Case Series

Cytomegalovirus (CMV) is the most common viral pathogen in kidney transplant recipients (KTRs), and CMV disease impacts patient and graft survivals. CMV-specific CD8 T cell mediated-immunity (CMI) may help to assess the risk of CMV disease and to adapt preventive treatment strategies. High-risk KTRs with CMV seropositive donors/seronegative recipients (D+/R-) were prospectively monitored after CMV prophylaxis discontinuation and during the first year post transplant for CMV viremia (World Health Organization standardization) and CMI (QuantiFERON-CMV). We analyzed the ability of CMI test to predict either subsequent spontaneous viral clearance or CMV disease after prophylaxis discontinuation in patients with asymptomatic viremia. We enrolled 12 consecutive (D+/R-) KTRs. Eleven patients developed a viremia during follow-up, but 7 of them (64%) exhibited a spontaneous viral clearance. At viremia onset, 6 of 11 patients (55%) had a positive CMI test, and all of them (6 of 6, 100%) had subsequent spontaneous viral clearance, compared with only 1 of 5 patients (20%) displaying a nonreactive CMI (P = .02). This latter patient exhibited a positive CMI test 15 days after viremia onset. Four of the 11 patients (36%) developed a CMV disease, and their CMI either remained nonreactive or became positive only after antiviral treatment. We conclude that D+/R- KTRs with asymptomatic viremia after prophylaxis discontinuation may benefit from QuantiFERON-CMV to predict when positive for the spontaneous viral clearance or when persistently negative or the development of a CMV disease.

Use of Viral Load as a Surrogate Marker in Clinical Studies of Cytomegalovirus in Solid Organ Transplantation: A Systematic Review and Meta-analysis

Symptomatic cytomegalovirus (CMV) disease has been the standard endpoint for clinical trials in organ transplant recipients. Viral load may be a more relevant endpoint due to low frequency of disease. We performed a meta-analysis and systematic review of the literature. We found several lines of evidence to support the validity of viral load as an appropriate surrogate end-point, including the following: (1) viral loads in CMV disease are significantly greater than in asymptomatic viremia (odds ratio, 9.3 95% confidence interval, 4.6-19.3); (2) kinetics of viral replication are strongly associated with progression to disease; (3) pooled incidence of CMV viremia and disease is significantly lower during prophylaxis compared with the full patient follow-up period (viremia incidence: 3.2% vs 34.3%; P < .001) (disease incidence: 1.1% vs 13.0%; P < .001); (4) treatment of viremia prevented disease; and (5) viral load decline correlated with symptom resolution. Based on the analysis, we conclude that CMV load is an appropriate surrogate endpoint for CMV trials in organ transplant recipients.

Early suppression of peripheral mononuclear blood cells in sepsis in response to stimulation with cytomegalovirus, OKT3, and pokeweed mitogen

Critically ill patients are at risk for sepsis, and immunosuppressive mechanisms may prevail. Whether functional tests are helpful to detect immune alterations is largely unknown. Therefore, we tested the hypotheses that reactivity of peripheral blood mononuclear cells (PBMCs) to secrete interferon-γ (IFNγ) following stimulation in vitro is decreased in patients with early sepsis compared with postoperative patients. IFNγ secretion [enzyme-linked immunospot (ELISpot)] in response to stimulation with cytomegalovirus (CMV), pokeweed mitogen (PWM), muromonab-anti-CD3 (OKT3), and human leukocyte antigen (HLA)-DRA-mRNA expression and serum cytokine concentrations were repeatedly [days 1, 3, 5, and 7 after intensive care unit (ICU) admission] determined in patients with sepsis (n = 7) and patients undergoing major abdominal surgery (radical prostatectomy, cystectomy, n = 10). In a second cohort, HLA-DRA expression was assessed in 80 patients with sepsis, 30 postoperative patients, and 44 healthy volunteers (German clinical trials database no. 00007694). In patients with sepsis, IFNγ secretion (ELISpot) was decreased compared with controls after stimulation with CMV (P = 0.01), OKT3 (P = 0.02), and PWM (P = 0.02 on day 5), whereas unstimulated IFNγ secretion did not differ. HLA-DRA expression was also significantly decreased in patients with sepsis at all time points (P = 0.004) compared with postoperative surgical patients, a finding confirmed in the larger cohort. Reactivity of PBMCs to stimulation with CMV, PWM, and OKT3 as well as HLA-DRA expression was already decreased upon ICU admission in patients with sepsis when compared with postoperative controls, suggesting early depression of acquired immunity. ELISpot assays may help to clinically characterize the time course of immunocompetence in patients with sepsis.NEW & NOTEWORTHY We observed suppression of reactivity to stimulation with cytomegalovirus, muromonab-anti-CD3, and pokeweed mitogen in mononuclear blood cells of patients with early sepsis when compared with postoperative controls. Thus, there is early depression of acquired immunity in sepsis. Enzyme-linked immunospot assays may help to characterize immunocompetence in patients with sepsis.

Efficacy and safety of the combination of reduced duration prophylaxis followed by immuno-guided prophylaxis to prevent cytomegalovirus disease in lung transplant recipients (CYTOCOR STUDY): an open-label, randomised, non-inferiority clinical trial

INTRODUCTION

Prolonged use of antivirals to prevent the development of cytomegalovirus (CMV) disease in lung transplant patients has been shown to have significant side effects, for which alternatives are being sought to reduce their use. The monitoring of cell immunity against CMV could be an alternative as it has shown to be useful in identifying transplant patients at low risk of infection, who could benefit from shorter prophylaxis. The aim of the CYTOCOR study is to demonstrate that the combination of a reduced prophylaxis strategy with subsequent CMV-specific immunological monitoring would allow CMV infection to be controlled in lung transplant patients as effectively as the usual strategy (prophylaxis followed by pre-emptive therapy), while reducing the side effects of antivirals due to the shorter duration of prophylaxis.

METHODS AND ANALYSIS

Phase III randomised, open, multicentre, parallel, non-inferiority clinical trial to study the efficacy and safety of the combination of a prophylaxis strategy up to month +3 post-transplant followed by immuno-guided prophylaxis using the QuantiFERON-CMV technique up to month +12 post-transplant to prevent CMV disease in CMV-seropositive lung transplant recipients. This strategy will be compared with a combination of a usual prophylaxis strategy up to month +6 post-transplant followed by pre-emptive therapy up to month +12. To study the incidence of CMV disease, patients will be followed up to 18 months post-transplantation. A total of 150 patients are expected to be recruited for the study.

ETHICS AND PUBLIC DISSEMINATION

The clinical trial has been approved by the Research Ethics Committees and authorised by the Spanish Agency of Medicines and Medical Devices (AEMPS).If the hypothesis of this clinical trial is verified, the dissemination of the results could change clinical practice by increasing knowledge about the safety and efficacy of discontinuing valganciclovir prophylaxis in lung transplant recipients.

TRIAL REGISTRATION NUMBER

NCT03699254.

Diagnostic performance of cytomegalovirus (CMV) immune monitoring with ELISPOT and QuantiFERON-CMV assay in kidney transplantation: A PRISMA-compliant article

BACKGROUND

Cytomegalovirus (CMV) infection is part of major infection complications following kidney transplantation. However, more rapid and low-complexity assays are needed for CMV infection. Our study is to investigate the diagnostic efficacy of 2 novel tests, CMV-ELISPOT and QuantiFERON-CMV tests, in CMV DNA viremia and CMV infection following renal transplant.

METHODS

We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials and the Web of Science. Case-control or cohort study designed to explore the CMV-ELISPOT and/or QuantiFERON-CMV tests in the recipients with CMV infection was considered to be eligible for this study. Sensitivity (SEN), specificity (SPE), diagnostic odds ratio (DOR), and summary receiver-operating characteristic (SROC) curves were calculated.

RESULTS

We selected a total of 12 articles for systematic review and 11 of them were included in meta-analysis. For CMV-pp65 assay, the pooled SEN, SPE, and DOR were 0.73 (95% confidence interval [CI], 0.67-0.78), 0.61 (95% CI, 0.56-0.65), and 4.46 (95% CI, 3.11-6.39), respectively. For CMV-IE-1 assay, the pooled SEN, SPE, and DOR were 0.84 (95% CI, 0.78-0.88), 0.46 (95% CI, 0.42-0.51), and 5.07 (95% CI, 3.26-7.89), respectively, whereas the pooled SEN, SPE, and DOR of QuantiFERON-CMV test were 0.38 (95% CI, 0.28-0.49), 0.38 (95% CI, 0.32-0.44), and 1.02 (95% CI, 0.17-6.00).

CONCLUSIONS

We reported that CMV-ELISPOT tests, including CMV-pp65 and CMV-IE-1, perform well in the diagnosis and prediction of CMV infection in renal transplant recipients, whereas QuantiFERON-CMV test needs further exploration.

Treatment and Prevention of CMV Disease in Transplant Recipients: Current Knowledge and Future Perspectives

This review summarizes the significant impact of cytomegalovirus (CMV) infection on solid organ and hematopoietic stem cell transplant recipients. A discussion of the various CMV prevention and treatment strategies is provided, including a detailed description of each of the available CMV antiviral drugs.