Assays Of Cell-mediated Immunity Research Articles

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

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. 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. 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.

Current and future strategies for the prevention and treatment of cytomegalovirus infections in transplantation.

Successful prevention and treatment of cytomegalovirus (CMV) infection remains a central focus of clinical care in solid organ and allogeneic hematopoietic cell transplantation. Over the past 5 years, pivotal clinical trials have created new paradigms in CMV prevention, including diverging approaches in HCT and SOT. We review recent advances in CMV risk assessment and progress in antiviral and immune-based strategies for CMV prevention and treatment. We highlight approaches to optimize CMV-specific immunity through vaccination, monoclonal antibodies, and virus-specific T-cells. Observational studies and interventional trials of commercially-available CMV cell-mediated immunity assays for refining preventive and treatment strategies are summarized. Finally, we discuss the importance of enhancing CMV-specific immunity to mitigate the negative impacts of CMV in different transplant settings. CMV infections in recipients of chimeric antigen receptor-T (CAR-T) cell therapies and other immunocompromised populations are growing areas of importance that are beyond the scope of this review.

Antiviral Agents for Preventing Cytomegalovirus Disease in Recipients of Hematopoietic Cell Transplantation.

This systematic review discusses the use of prophylaxis to prevent cytomegalovirus (CMV) infection in recipients who have undergone hematopoietic cell transplantation. It highlights the need for new approaches to control and prevent CMV infection. The approval of the anti-CMV drug letermovir has made antiviral prophylaxis more popular. CMV-specific T cell-mediated immunity tests are effective in identifying patients who have undergone immune reconstitution and predicting disease progression. Maribavir (MBV) has been approved for the treatment of post-transplant CMV infection/disease in adolescents. Adoptive T-cell therapy and the PepVax CMV vaccine show promise in tackling refractory and resistant CMV. However, the effectiveness of PepVax in reducing CMV viremia/disease was not demonstrated in a phase II trial. Cell-mediated immunity assays are valuable for personalized management plans, but more interventional studies are needed. MBV and adoptive T-cell therapy are promising treatments, and trials for CMV vaccines are ongoing.

The Presence of esat-6 and cfp10 and Other Gene Orthologs of the RD 1 Region in Non-Tuberculous Mycobacteria, Mycolicibacteria, Mycobacteroides and Mycolicibacter as Possible Impediments for the Diagnosis of (Animal) Tuberculosis.

The Esx-1 family proteins of the Type VII secretion systems of Mycobacterium bovis and Mycobacterium tuberculosis have been assessed and are frequently used as candidates for tuberculosis (TB) diagnosis in both humans and animals. The presence of ESAT-6 and CFP 10 proteins, which are the most immunogenic proteins of the Esx-1 system and have been widely investigated for the immunodiagnosis of tuberculosis, in some Mycobacteriaceae and in Mycobacterium leprae, poses limitations for their use in specific diagnoses of TB. As such, to improve the specificity of the ESAT-6/CFP 10-based cell-mediated immunity (CMI) assays, other proteins encoded by genes within and outside the RD 1 region of the esx-1 locus have been evaluated as candidate antigens for CMI, as well as to investigate humoral responses in combination with ESAT-6 and or CFP 10, with varying specificity and sensitivity results. Hence, in this study, we evaluated various non-tuberculous mycobacteria (NTM), Mycolicibacterium, Mycolicibacter and Mycobacteroides species genomes available on the NCBI database for the presence and composition of the RD1 region of the esx-1 locus. In addition, we also assayed by polymerase chain reaction (PCR) and sequencing of Mycobacteriaceae available in our culture collection for the presence and sequence diversity of esxA and esxB genes encoding ESAT-6 and CFP 10, respectively. Whole genome sequence (WGS) data analysis revealed the presence of RD 1 gene orthologs in 70 of the over 100 published genomes of pathogenic and non- pathogenic Mycobcteriaceae other than tuberculosis. Among species evaluated from our culture collection, in addition to earlier reports of the presence of esxA and esxB in certain Mycolicibacterium, Mycolicibacterium septicum/peregrinum, Mycolicibacterium porcinum and Mycobacterium sp. N845T were also found to harbour orthologs of both genes. Orthologs of esxA only were detected in Mycobacterium brasiliensis, Mycolicibacterium elephantis and Mycolicibacterium flouroantheinivorans, whereas in Mycolicibacter engbackii, Mycolicibacterium mageritense and Mycobacterium paraffinicum, only esxB orthologs were detected. A phylogenetic analysis based on esxA and esxB sequences separated slow-growing from rapidly growing bacteria. These findings strengthen previous suggestions that esxA and esxB may be encoded in the majority of Mycobacteriaceae. The role of the Esx-1 system in both pathogenic and non-pathogenic Mycobacteriaceae needs further investigation, as these species may pose limitations to immunological assays for TB.

The changing landscape of infections in the lung transplant recipient.

Infections in lung transplant recipients remain a major challenge and can affect lung allograft function and cause significant morbidity and mortality. New strategies for the prevention and treatment of infection in lung transplantation have emerged and are reviewed. For important vaccine preventable infections (VPIs), guidance has been updated for at risk solid organ transplant (SOT) recipients. However, data on the efficacy of newer vaccines in lung transplant, including the respiratory syncytial virus (RSV) vaccine, are limited. Studies demonstrate improved vaccination rate with Infectious Diseases consultation during pretransplant evaluation. Two new antiviral agents for the treatment and prevention of cytomegalovirus (CMV) in SOT, letermovir and maribavir, are being incorporated into clinical care. CMV-specific cell-mediated immune function assays are more widely available. Antibiotics for the management of multidrug resistant pathogens and Burkholderia cepacia complex have been described in case series and case reports in lung transplant. Although new vaccines and novel therapies for preventing and treating infections are available, larger studies evaluating efficacy in lung transplant recipients are needed.

Advancing cytomegalovirus prevention in solid organ transplant recipients: The promise of cell-mediated immune assays.

Cytomegalovirus (CMV) infections are a major source of morbidity and mortality in solid organ transplant recipients. Prophylactic, preemptive, and hybrid prevention strategies have traditionally been the mainstay of CMV prevention but there is growing interest in the use of CMV cell-mediated immune assays to inform novel approaches to risk stratification. Recent evidence suggests that CMV interferon-gamma release assays can offer predictive insights into the risk for CMV-related illnesses, raising the potential for tailored CMV prevention strategies anchored to each individual's unique CMV immune profile. However, the predictive capacity of these assays for CMV-related illnesses can be profoundly influenced by when they are performed relative to transplant, and the induction immunosuppressive regimen the patient has received. In this review, we explore the relevant literature shaping our understanding of the optimal use of these assays. Furthermore, we also highlight the benefits of quantifying the CD4+ and CD8+ T-Cell responses to CMV, which is offered by some interferon-gamma release assays utilizing intracellular cytokine staining, for providing a holistic assessment of the recovery of cell-mediated immunity post-induction immunosuppression.

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.

New Perspectives in Cytomegalovirus After Transplant: The Role of Immunosuppressant Management.

New Perspectives in Cytomegalovirus After Transplant: The Role of Immunosuppressant Management.

Performance of an interferon-γ release assay-based test for cell-mediated immunity to SARS-CoV-2.

In search for immunological correlates of protection against acute coronavirus disease 2019 (COVID-19) there is a need for high through-put assays for cell-mediated immunity (CMI) to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We established an interferon-γ release assay -based test for detection of CMI against SARS-CoV-2 spike (S) or nucleocapsid (NC) peptides. Blood samples obtained from 549 healthy or convalescent individuals were measured for interferon-γ (IFN-γ) production after peptide stimulation using a certified chemiluminescence immunoassay. Test performance was calculated applying cutoff values with the highest Youden indices in receiver-operating-characteristics curve analysis and compared to a commercially available serologic test. Potential confounders and clinical correlates were assessed for all test systems. 522 samples obtained from 378 convalescent in median 298 days after PCR-confirmed SARS-CoV-2 infection and 144 healthy control individuals were included in the final analysis. CMI testing had a sensitivity and specificity of up to 89% and 74% for S peptides and 89% and 91% for NC peptides, respectively. High white blood cell counts correlated negatively with IFN-γ responses but there was no CMI decay in samples obtained up to one year after recovery. Severe clinical symptoms at time of acute infection were associated with higher measures of adaptive immunity and reported hair loss at time of examination. This laboratory-developed test for CMI to SARS-CoV-2 NC peptides exhibits excellent test performance, is suitable for high through-put routine diagnostics, and should be evaluated for clinical outcome prediction in prospective pathogen re-exposure.

Update on the management of cytomegalovirus infection in transplant recipients

Cytomegalovirus (CMV) infection remains a significant infectious complication after transplantation. In this article, we summarize the recent advances in the management of CMV infection in solid-organ and hematopoietic stem-cell transplant recipients. Firstly, recent trials have better delineated the indications for the preventive strategies available, namely antiviral prophylaxis and the preemptive approach. Secondly, the antiviral armamentarium has been expanded with the advent of less toxic oral drugs that are available for antiviral prophylaxis and for therapy of refractory/resistant CMV infection. Finally, increasing evidence suggests that cell-mediated immune assays can be used in routine care for individualizing the prevention strategies against CMV.

Utility of Cytomegalovirus Cell-Mediated Immunity Assays in Solid Organ Transplantation.

Cytomegalovirus (CMV) is one of the most important viral complications after solid organ transplantation (SOT). Current preventive and management strategies rely primarily on serologic and viral load testing and remain suboptimal. To address these issues, multiple techniques to measure CMV-specific cell-mediated immunity (CMI) have been developed and evaluated in clinical studies over the past two decades. These assays show significant promise for the personalization of CMV management. For example, CMI assays can be used to help determine the optimal duration of antiviral prophylaxis or whether antiviral therapy is indicated in patients with low levels of CMV reactivation. However, despite numerous studies showing potential utility, these assays are not yet in widespread routine clinical use. Barriers to adoption include variations in test complexity, standardization, and thresholds for positivity and insufficient interventional clinical trials. Here, we provide an updated assessment of commonly available tests and the clinical utility of CMV-specific CMI testing in SOT recipients.

CMV Infection in Hematopoietic Stem Cell Transplantation: Prevention and Treatment Strategies.

Purpose of ReviewCytomegalovirus (CMV) remains a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (Allo-HSCT). New strategies and methods for prevention and management of CMV infection are urgently needed. We aim to review the new developments in diagnostics, prevention, and management strategies of CMV infection in Allo-HSCT recipients.Recent FindingsThe approval of the novel anti-CMV drug letermovir in 2017 has led to an increase in the use of antiviral prophylaxis as a preferred approach for prevention in many centers. Real-world studies have shown efficacy similar to the clinical trial. CMV-specific T cell-mediated immunity assays identify patients with immune reconstitution and predict disease progression. Phase 2 trials of maribavir have shown its efficacy as preemptive therapy and treatment of resistant and refractory CMV infections. Adoptive T cell therapy is an emerging option for treatment of refractory and resistant CMV. Of the different CMV vaccine trials, PepVax has shown promising results in a phase 1 trial.SummaryCMV cell-mediated immunity assays have potential to be used as an adjunctive test to develop individualized management plan by identifying the patients who develop immune reconstitution; however, further prospective interventional studies are needed. Maribavir and adoptive T cell therapy are promising new therapies for treatment of CMV infections. CMV vaccine trials for prevention are also under way.

Application of the gamma-interferon assay to determine the prevalence of bovine tuberculosis in slaughter livestock at abattoirs in Gauteng, South Africa.

Bovine tuberculosis (bTB) is a zoonotic disease with great economic impact estimated at billions of dollars annually worldwide. Meat inspection represents a long-standing form of disease surveillance that serves both food safety and animal health. The objective of this study was to determine the prevalence of bTB in livestock at abattoirs using a cell-mediated immune (CMI) assay, the gamma interferon (IFN-γ) assay. This cross-sectional study was conducted at selected abattoirs (low-throughput, high-throughput and rural/informal) in Gauteng province, where animals were also subjected to routine meat inspection. A total of 410 fresh blood samples were collected from slaughter livestock (369 cattle and 41 sheep) from 15 abattoirs, and analysed using Bovigam® test kit with bovine, avian and Fortuitum purified protein derivatives (PPD) as blood stimulating antigens. The estimated prevalence of bTB in cattle was 4.4% (95% CI: 2.4%-7.3%). The prevalence of bTB in cattle varied between abattoirs (p=.005), ranging from 0% to 23%; however, there were no significant differences among genders, breeds, municipality, districts, origins of animals (feedlot, auction or farm) or throughput of abattoirs. The prevalence of avian reactors was 6.0% (95% CI: 3.6%-9.2%) in cattle, varying between abattoirs (p=.004) and ranging from 0% to 20.7%. None of the sheep with valid test results was positive for bTB and none was avian reactors (95% CI: 0%-15%). The detection of bTB reactor cattle in our study clearly shows the limitation of disease surveillance using a meat inspection approach, as all the 410 slaughter animals sampled had passed visual abattoir inspection and been classified as bTB-free. Our findings therefore emphasize the risk of zoonotic transmission of bTB to abattoir workers and potential food safety hazard to consumers. Furthermore, our study highlights the potential for the use of the IFN-γ assay to reduce this risk.

Update on cytomegalovirus in transplant recipients: new agents, prophylaxis, and cell-mediated immunity.

This review is an overview of recent advances in diagnostics, therapies, and prevention strategies for cytomegalovirus (CMV), focusing on solid-organ transplant and hematopoietic stem cell transplant recipients. A randomized trial of prophylaxis vs preemptive therapy in donor-seropositive, recipient-seronegative liver transplant recipients found significantly less CMV disease in the preemptive group. Maribavir has shown promise for the treatment of resistant/refractory CMV and for uncomplicated CMV DNAemia. A post hoc mortality analysis, as well as emerging reports of real-world and off-label use, have expanded the spectrum of clinical experience with letermovir. The first interventional trials using CMV cell-mediated immune assays have been published and showed promising results for delineating antiviral strategies. New data from additional interventional trials are expected soon. The past 1-2 years have seen major developments in the area of CMV management in transplant recipients. Expanding diagnostic and therapeutic capabilities provide a foundation for optimizing strategies in the future, to reduce morbidity and mortality from CMV.

Cytomegalovirus in Solid Organ Transplant Recipients: Clinical Updates, Challenges and Future Directions.

Cytomegalovirus is the classic opportunistic infection after solid organ transplantation. This review will discuss updates and future directions in the diagnosis, prevention and treatment of CMV infection in solid organ transplant recipients. Antiviral prophylaxis and pre-emptive therapy are the mainstays of CMV prevention, but they should not be mutually exclusive and each strategy should be considered depending on a specific situation. The lack of a widely applicable viral load threshold for diagnosis and preemptive therapy is emphasized as a major factor that should pave the way for an individualized approach to prevention. Valganciclovir and intravenous ganciclovir remain as drugs of choice for CMV management, and strategies for managing drug-resistant CMV infection are enumerated. There is increasing use of CMV-specific cell-mediated immune assays to stratify the risk of CMV infection after solid organ transplantation, and their potential role in optimizing CMV prevention and treatment efforts is discussed.

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.

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. 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. 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%. 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.

Assay of CMV Cell-Mediated Immunity Fails to Predict Risk for CMV Infection After Kidney Transplantation

Assays that measure cytomegalovirus (CMV) cell-mediated immunity (CMI) are being tested to individualize the duration of antiviral preventive treatment

Cytomegalovirus in solid organ transplant recipients-Guidelines of the American Society of Transplantation Infectious Diseases Community of Practice.

Cytomegalovirus (CMV) is one of the most common opportunistic infections that affect the outcome of solid organ transplantation. This updated guideline from the American Society of Transplantation Infectious Diseases Community of Practice provides evidence-based and expert recommendations for screening, diagnosis, prevention, and treatment of CMV in solid organ transplant recipients. CMV serology to detect immunoglobulin G remains as the standard method for pretransplant screening of donors and transplant candidates. Antiviral prophylaxis and preemptive therapy are the mainstays of CMV prevention. The lack of a widely applicable viral load threshold for diagnosis and preemptive therapy is highlighted, as a result of variability of CMV nucleic acid testing, even in the contemporary era when calibrators are standardized. Valganciclovir and intravenous ganciclovir remain as drugs of choice for CMV management. Strategies for managing drug-resistant CMV infection are presented. There is an increasing use of CMV-specific cell-mediated immune assays to stratify the risk of CMV infection after solid organ transplantation, but their role in optimizing CMV prevention and treatment efforts has yet to be demonstrated. Specific issues related to pediatric transplant recipients are discussed.

Evaluation of the immunogenicity and safety of different doses and formulations of a broad spectrum influenza vaccine (FLU-v) developed by SEEK: study protocol for a single-center, randomized, double-blind and placebo-controlled clinical phase IIb trial

BackgroundCurrent influenza vaccines, based on antibodies against surface antigens, are unable to provide protection against newly emerging virus strains which differ from the vaccine strains. Therefore the population has to be re-vaccinated annually. It is thus important to develop vaccines which induce protective immunity to a broad spectrum of influenza viruses. This trial is designed to evaluate the immunogenicity and safety of FLU-v, a vaccine composed of four synthetic peptides with conserved epitopes from influenza A and B strains expected to elicit both cell mediated immunity (CMI) and humoral immunity providing protection against a broad spectrum of influenza viruses.MethodsIn a single-center, randomized, double-blind and placebo-controlled phase IIb trial, 222 healthy volunteers aged 18–60 years will be randomized (2:2:1:1) to receive two injections of a suspension of 500 μg FLU-v in saline (arm 1), one dose of emulsified 500 μg FLU-v in Montanide ISA-51 and water for injection (WFI) followed by one saline dose (arm 2), two saline doses (arm 3), or one dose of Montanide ISA-51 and WFI emulsion followed by one saline dose (arm 4). All injections will be given subcutaneously. Primary endpoints are safety and FLU-v induced CMI, evaluated by cytokine production by antigen specific T cell populations (flow-cytometry and ELISA). Secondary outcomes are measurements of antibody responses (ELISA and multiplex), whereas exploratory outcomes include clinical efficacy and additional CMI assays (ELISpot) to show cross-reactivity.DiscussionBroadly protective influenza vaccines able to provide protection against multiple strains of influenza are urgently needed. FLU-v is a promising vaccine which has shown to trigger the cell-mediated immune response. The dosages and formulations tested in this current trial are also estimated to induce antibody response. Therefore, both cellular and humoral immune responses will be evaluated.Trial registrationEudraCT number 2015–001932-38; retrospectively registered clinicaltrials.gov NCT02962908 (November 7th 2016).

Screening for immune response against Dengue virus in Vietnamese non-human primates: implications for vaccine developers.

One of the major problems faced for the development of a vaccine against Dengue virus is the lack of a suitable animal model. Although non-human primates do not show overt signs of disease, these animals develop viremia after the infection and are the best model to evaluate vaccine candidates against this pathogen. However, for that purpose, the screening of all animals is mandatory to discard those with previous natural immunity. The most common technique used in the screening is the plaque reduction neutralization test (PRNT). However, most recent studies points to the cell-mediated immunity (CMI) as an important player in the process of controlling Dengue virus (DENV) infections. Here we presented the results from the screening of 55 rhesus monkeys housed in an animal breeding facility at Quang Ninh province, Vietnam. We evaluated the neutralizing antibody response by PRNT and determined the levels of interferon γ (IFNγ)-secretion after the viral stimulation of monkey-peripheral blood mononuclear cells, by enzyme-linked immunosorbent assay (ELISA). We found no correspondence between PRNT and IFNγ-ELISA. In fact, 19 animals were positive only by IFNγ-ELISA. Moreover, to study the protective capacity of the CMI detected, three animals with positive response by IFNγ-ELISA and negative by PRNT were inoculated with an infective preparation of DENV-3 and, as a result, no viremia was detected during 10 days after the challenge. This fact points to the importance of screening non-human primates through a CMI assay together with PRNT. This procedure should discard those false-negative cases which would be protected after the viral challenge in the immunization schedule.