Monitoring human cytomegalovirus infection in transplant recipients

Clinical phenotypes and prognosis of cytomegalovirus infection in the pediatric systemic lupus erythematosus: a longitudinal analysis

BACKGROUND

Cytomegalovirus (CMV) plays an important role in the pathogenesis of systemic lupus erythematosus (SLE). However, it is not clear whether the anti-CMV treatment has an impact on the prognosis of SLE patients with CMV infection. We aimed to analyze the clinical characteristics and prognosis of CMV infection in pediatric SLE (pSLE) and to evaluate the effect of anti-CMV treatment on pSLE outcome.

METHODS

A retrospective study including 146 pSLE from 2012 to 2021 was conducted. CMV-positive and CMV-negative groups were compared by univariate analysis and stepwise logistic multiple regression to analyze the clinical characteristics of CMV infection in pSLE. Generalized estimating equations (GEE) were used to model the longitudinal dynamics of pSLE disease activity with or without CMV infection and anti-CMV treatment.

RESULTS

The CMV infection rate was 74.7% (109/146) in this pSLE cohort. CMV-positive pSLE patients were more likely to present positive anti-dsDNA antibody, hypocomplementemia, high SLEDAI-2K score and musculoskeletal involvement (P < 0.05). Survival analysis showed that CMV-positive pSLE patients were more prone to disease flare and poorer outcomes. GEE modeling indicated that CMV phosphoprotein 65 (pp65) titers were positively correlated with SLEDAI-2K, and anti-CMV treatment could better reduce pSLE activity than non-treatment (P < 0.05).

CONCLUSIONS

CMV infection is highly prevalent among pSLE patients. Positive anti-dsDNA antibody, hypocomplementemia, high SLEDAI-2K score and musculoskeletal involvement were significant clinical clues indicating CMV infections in pSLE. CMV infection is correlated with higher disease activity and poorer outcome. Anti-CMV treatment can reduce disease activity and flares.

Antibodies to combat viral infections: development strategies and progress

Monoclonal antibodies (mAbs) are appealing as potential therapeutics and prophylactics for viral infections owing to characteristics such as their high specificity and their ability to enhance immune responses. Furthermore, antibody engineering can be used to strengthen effector function and prolong mAb half-life, and advances in structural biology have enabled the selection and optimization of potent neutralizing mAbs through identification of vulnerable regions in viral proteins, which can also be relevant for vaccine design. The COVID-19 pandemic has stimulated extensive efforts to develop neutralizing mAbs against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with several mAbs now having received authorization for emergency use, providing not just an important component of strategies to combat COVID-19 but also a boost to efforts to harness mAbs in therapeutic and preventive settings for other infectious diseases. Here, we describe advances in antibody discovery and engineering that have led to the development of mAbs for use against infections caused by viruses including SARS-CoV-2, respiratory syncytial virus (RSV), Ebola virus (EBOV), human cytomegalovirus (HCMV) and influenza. We also discuss the rationale for moving from empirical to structure-guided strategies in vaccine development, based on identifying optimal candidate antigens and vulnerable regions within them that can be targeted by antibodies to result in a strong protective immune response.

Transition from antigenemia to quantitative nucleic acid amplification testing in cytomegalovirus-seropositive kidney transplant recipients receiving preemptive therapy for cytomegalovirus infection

Due to the high costs, the strategy to reduce the impact of cytomegalovirus (CMV) after kidney transplant (KT) involves preemptive treatment in low and middle-income countries. Thus, this retrospective cohort study compared the performance of antigenemia transitioned to quantitative nucleic acid amplification testing, RT-PCR, in CMV-seropositive KT recipients receiving preemptive treatment as a strategy to prevent CMV infection. Between 2016 and 2018, 363 patients were enrolled and received preemptive treatment based on antigenemia (n = 177) or RT-PCR (n = 186). The primary outcome was CMV disease. Secondarily, the CMV-related events were composed of CMV-infection and disease, which occurred first. There were no differences in 1-year cumulative incidence of CMV-disease (23.7% vs. 19.1%, p = 0.41), CMV-related events (50.8% vs. 44.1%, p = 0.20), neither in time to diagnosis (47.0 vs. 47.0 days) among patients conducted by antigenemia vs. RT-PCR, respectively. The length of CMV first treatment was longer with RT-PCR (20.0 vs. 27.5 days, p < 0.001), while the rate of retreatment was not different (14.7% vs. 11.8%, p = 0.48). In the Cox regression, acute rejection within 30 days was associated with an increased the risk (HR = 2.34; 95% CI = 1.12-4.89; p = 0.024), while each increase of 1 mL/min/1.73 m² of 30-day eGFR was associated with a 2% reduction risk of CMV-disease (HR = 0.98; 95% CI = 0.97-0.99; p = 0.001). In conclusion, acute rejection and glomerular filtration rate are risk factors for CMV disease, showing comparable performance in the impact of CMV-related events between antigenemia and RT-PCR for preemptive treatment.

Factors associated with cytomegalovirus antigenemia in patients with rheumatic disease: A retrospective study

INTRODUCTION

This study aimed to examine the factors associated with cytomegalovirus (CMV) antigenemia and the time of onset of CMV antigenemia among patients with rheumatic diseases.

METHODS

A single-center, retrospective, observational study was conducted in our institution from January 2009 to December 2017. This study included patients with rheumatic diseases who had at least one CMV antigen measurement. Multivariate analysis and receiver operating characteristic analysis was performed.

RESULTS

A total of 249 patients underwent CMV antigenemia assay, and 84 (33.7%) patients tested positive. When the association between CMV antigenemia and possible associated factors was investigated, multivariate analysis showed that daily steroid dose increased the odds of having CMV [odds ratio 16.25, 95% confidence interval (CI), 5.360-49.253]. In this study, the cutoff value of daily steroid dose found in this study (0.45 mg/kg/day) was reasonable in clinical practice, and the area under the curve of the steroid dose was 0.838 [95% CI 0.781-0.882], which was the largest of the known indicators. Moreover, the median time from the start of immunosuppressive therapy to the onset of CMV antigenemia was 30 (interquartile range, 21-44) days, and most of the daily steroid users (85.7%) developed CMV antigenemia within 60 days.

CONCLUSIONS

The daily steroid dose is the most important factor associated with CMV antigenemia. Therefore, monitoring and treatment strategies based on the steroid dose, especially in the initial 2 months, are important.

Pretransplant BK Virus-Specific T-Cell-Mediated Immunity and Serotype Specific Antibodies May Have Utility in Identifying Patients at Risk of BK Virus-Associated Haemorrhagic Cystitis after Allogeneic HSCT

BK polyomavirus (BKPyV) persists lifelong in renal and urothelial cells with asymptomatic urinary shedding in healthy individuals. In some immunocompromised persons after transplantation of hematopoietic stem cells (HSCT), the BKPyV high-rate replication is associated with haemorrhagic cystitis (HC). We tested whether the status of BKPyV immunity prior to HSCT could provide evidence for the BKPyV tendency to reactivate. We have shown that measurement of pretransplant anti-BKPyV 1 and 4 IgG levels can be used to evaluate the HC risk. Patients with anti-BKPyV IgG in the range of the 1st-2nd quartile of positive values and with positive clinical risk markers have a significantly increased HC risk, in comparison to the reference group of patients with "non-reactive" anti-BKPyV IgG levels and with low clinical risk (LCR) (p = 0.0009). The predictive value of pretransplant BKPyV-specific IgG was confirmed by determination of genotypes of the shed virus. A positive predictive value was also found for pretransplant T-cell immunity to the BKPyV antigen VP1 because the magnitude of IFN-γ T-cell response inversely correlated with posttransplant DNAuria and with HC. Our novel data suggest that specific T-cells control BKPyV latency before HSCT, and in this way may influence BKPyV reactivation after HSCT. Our study has shown that prediction using a combination of clinical and immunological pretransplant risk factors can help early identification of HSCT recipients at high risk of BKPyV disease.

Impact of CMV Reactivation, Treatment Approaches, and Immune Reconstitution in a Nonmyeloablative Tolerance Induction Protocol in Cynomolgus Macaques

BACKGROUND

Cytomegalovirus (CMV) infection is a serious complication in immunosuppressed patients, specifically transplant recipients. Here, we describe the development and use of an assay to monitor the incidence and treatment of CMV viremia in a Cynomolgus macaque model of bone marrow transplantation (BMT) for tolerance induction. We address the correlation between the course of viremia and immune reconstitution.

METHODS

Twenty-one animals received a nonmyeloablative conditioning regimen. Seven received cyclosporine A for 28 days and 14 received rapamycin. A CMV polymerase chain reaction assay was developed and run twice per week to monitor viremia. Nineteen recipients were CMV seropositive before BMT. Immune reconstitution was monitored through flow cytometry and CMV viremia was tracked via quantitative polymerase chain reaction.

RESULTS

Recipients developed CMV viremia during the first month post-BMT. Two animals developed uncontrollable CMV disease. CMV reactivation occurred earlier in cyclosporine A-treated animals compared with those receiving rapamycin. Post-BMT, T-cell counts remained significantly lower compared with pretransplant levels until CMV reactivation, at which point they increased during the viremic phase and approached pretransplant levels 3 months post-BMT. Management of CMV required treatment before viremia reached 10 000 copies/mL; otherwise clinical symptoms were observed. High doses of ganciclovir resolved the viremia, which could subsequently be controlled with valganciclovir.

CONCLUSIONS

We developed an assay to monitor CMV in Cynomolgus macaques. CMV reactivation occurred in 100% of seropositive animals in this model. Rapamycin delayed CMV reactivation and ganciclovir treatment was effective at high doses. As in humans, CD8 T cells proliferated during CMV viremia.

Cytomegalovirus Retinitis in HIV and Non-HIV Individuals

Cytomegalovirus retinitis (CMVR) is a severe, vision-threatening disease that primarily affects immunosuppressed patients. CMVR is the most common ocular opportunistic infection in human immunodeficiency virus (HIV) infected patients and is the leading cause of blindness in this group; however, the incidence of CMVR in HIV patients has dramatically decreased with antiretroviral therapy. Other causes of immunosuppression, including organ transplantation, hematologic malignancies, and iatrogenic immunosuppression, can also lead to the development of CMVR. Herein, we describe the pathogenesis of CMVR and compare clinical features, epidemiology, and risk factors in HIV and non-HIV infected individuals with CMVR.

Cytomegalovirus Induced Collapsing Glomerulopathy and Necrotizing Glomerulonephritis in a Renal Allograft Recipient

In renal allograft recipients, cytomegalovirus (CMV) typically causes tubulointerstitial nephritis. Only rarely glomeruli are involved. We present a rare case of CMV with collapsing glomerulopathy, necrotizing glomerulonephritis, and crescent formation in a renal allograft recipient. Immunohistochemistry confirmed CMV infection. The patient was started on valganciclovir and his renal function remained stable. A repeat renal biopsy performed three months later showed morphologically normal glomeruli and CMV immunostaining was also negative. Nephropathologists have to carefully screen for CMV in cases with crescentic or collapsing glomerulopathy as the later lesions resolve after treating the underlying viral infection. This study will add on to the various glomerular changes associated with CMV infection.

A high level of urinary retinol-binding protein is associated with cytomegalovirus infection in kidney transplantation

The indirect effects of cytomegalovirus (CMV) viremia can be related to chronic changes in renal allograft structure, but its real impact in early and late graft function remains speculative. A total of 159 patients undergoing renal transplantation using a preemptive therapeutic strategy to prevent CMV disease were included in the present study. The patients were prospectively followed, with serial measurements of urinary retinol-binding protein (uRBP), a marker of proximal tubule injury. uRBP levels and their dynamic performance were compared according to CMV viremia and the 5-year estimated glomerular filtration rate (eGFR), as measured with the modification of diet in renal disease (MDRD) equation. CMV viremia was detected in 79.9% of the patients, with high uRBP levels being detected in 76.0% of these patients (compared with 40.7% in CMV-, P=0.005). High uRBP was associated with male recipients (P=0.02), the number of mismatches (P=0.02) and CMV infection (P=0.001). Five-year eGFR was worse in patients with high uRBP levels (50.3 ± 25.8 compared with 59.8 ± 26.4 ml/min, P=0.04). In a multivariate model, eGFR <60 ml/min was associated with donor age (P<0.001), the number of mismatches (P=0.04), thymoglobulin dose (P=0.02), the presence of and time with delayed graft function (DGF) (P=0.005 and P=0.04), 1-month tacrolimus levels (P=0.03), and uRBP levels after CMV treatment (P=0.01). Patients with CMV viremia in whom uRBP levels were normalized up to 3 months after treatment showed significantly better 5-year eGFR than those in whom uRBP remained high: 61.0 ± 24.2 compared with 42.3 ± 23.9 ml/min, P<0.001. CMV viremia was associated with high uRBP levels, which represent a profile of proximal tubule injury, and the dynamic performance of uRBP after treatment was associated with long-term kidney graft function.

New therapies for human cytomegalovirus infections

The recent approval of letermovir marks a new era of therapy for human cytomegalovirus (HCMV) infections, particularly for the prevention of HCMV disease in hematopoietic stem cell transplant recipients. For almost 30 years ganciclovir has been the therapy of choice for these infections and by today's standards this drug exhibits only modest antiviral activity that is often insufficient to completely suppress viral replication, and drives the selection of drug-resistant variants that continue to replicate and contribute to disease. While ganciclovir remains the therapy of choice, additional drugs that inhibit novel molecular targets, such as letermovir, will be required as highly effective combination therapies are developed not only for the treatment of immunocompromised hosts, but also for congenitally infected infants. Sustained efforts, largely in the biotech industry and academia, have identified additional highly active lead compounds that have progressed into clinical studies with varying levels of success and at least two have the potential to be approved in the near future. Some of the new drugs in the pipeline inhibit new molecular targets, remain effective against isolates that have developed resistance to existing therapies, and promise to augment existing therapeutic regimens. Here, we will describe some of the unique features of HCMV biology and discuss their effect on therapeutic needs. Existing drugs will also be discussed and some of the more promising candidates will be reviewed with an emphasis on those progressing through clinical studies. The in vitro and in vivo antiviral activity, spectrum of antiviral activity, and mechanism of action of new compounds will be reviewed to provide an update on potential new therapies for HCMV infections that have progressed significantly in recent years.

Preemptive anti-cytomegalovirus therapy in high-risk (donor-positive, recipient-negative cytomegalovirus serostatus) kidney transplant recipients

OBJECTIVES

Universal prophylaxis and preemptive therapy are used to prevent cytomegalovirus (CMV) disease post-transplantation. Data regarding which strategy is superior are sparse, especially in high-risk recipients (donor CMV seropositive (D+) and recipient CMV seronegative (R-)).

METHODS

This retrospective, single-center cohort study included recipients who underwent kidney transplantation between 2009 and 2015. The incidence of CMV infection/disease and patient and graft outcomes were analyzed and compared between high-risk recipients (D+/R-) and intermediate-risk recipients (D+/R+ or D-/R+), all managed with preemptive therapy.

RESULTS

Of 118 kidney transplant recipients, 21 were high-risk and 97 were intermediate-risk. Over a median follow-up period of 3 years, asymptomatic CMV infection developed significantly more frequently in high-risk patients than in intermediate-risk patients (38.1% vs. 16.5%, p=0.04), and CMV disease developed in a similar manner (28.6% vs. 3.1%, p<0.01). Among high-risk patients, CMV infection developed within the first 3 months post-transplantation and CMV disease within the first 9 months post-transplantation. Kaplan-Meier analysis showed no difference in the probability of mortality (log-rank p=0.63) or graft loss (log-rank p=0.50) between the patient groups. Graft rejection occurred more frequently in high-risk than in intermediate-risk patients, but the difference was not significant (log-rank p=0.24).

CONCLUSIONS

These results suggest that further studies on universal prophylaxis in high-risk patients are needed to elucidate whether preventing CMV infection/disease during the early post-transplant period leads to better outcomes, especially in terms of reducing graft rejection.

Enzyme-Linked Immunospot Assay as a Complementary Method to Assess and Monitor Cytomegalovirus Infection in Kidney Transplant Recipients on Pre-emptive Antiviral Therapy: A Single-Center Experience

BACKGROUND

Cytomegalovirus (CMV) disease represents a major cause of post-transplantation morbidity and mortality. To estimate the risk of infection and monitor response to antiviral therapy, current guidelines suggest combination of viral load monitoring with direct assessment of CMV-specific immune response. We used enzyme-linked immunospot (ELISpot) for the evaluation of CMV-specific T-cell response in kidney transplant recipients with CMV viremia and investigated how information gained could help manage CMV infection.

METHODS

Seventeen patients on pre-emptive antiviral therapy and CMV quantitative polymerase chain reaction (qPCR) ≥500 copies/mL (first episode after transplantation) were assessed using ELISpot and divided into Weak (9 patients with baseline ELISpot <25 spot-forming colonies [SFCs]/200,000 peripheral blood mononuclear cells [PBMCs]) and Strong Responders (8 patients with baseline ELISpot ≥25 SFCs/200,000 PBMCs). CMV-specific T-cell response, infection severity, viral load, and antiviral therapy were prospectively recorded and compared between groups at 1, 2, and 24 months of follow-up.

RESULTS

Demographic and transplant characteristics of Weak and Strong Responders were similar. No episodes of CMV disease were observed. Weak Responders were more likely to experience CMV syndrome (56% vs 36.5%) and late virus reactivation (56% vs 25%) than Strong Responders. Weak Responders showed higher baseline median viral loads (19,700 vs 9265 copies/mL) and needed antiviral therapy for longer (179 vs 59.5 days). T-cell response showed 2 main patterns: early and delayed.

CONCLUSIONS

ELISpot provides prognostic information about infection severity, risk of late reactivation, and response to therapy. Randomized trials, evaluating the need for antiviral therapy in kidney transplant recipients with asymptomatic infection and effective virus-specific T-cell immune response, are warranted.

Performance Evaluation of the Real-Q Cytomegalovirus (CMV) Quantification Kit Using Two Real-Time PCR Systems for Quantifying CMV DNA in Whole Blood

Standardized cytomegalovirus (CMV) DNA quantification is important for managing CMV disease. We evaluated the performance of the Real-Q CMV Quantification Kit (Real-Q assay; BioSewoom, Korea) using whole blood (WB), with nucleic acid extraction using MagNA Pure 96 (Roche Diagnostics, Germany). Real-time PCR was performed on two platforms: the 7500 Fast real-time PCR (7500 Fast; Applied Biosystems, USA) and CFX96 real-time PCR detection (CFX96; Bio-Rad, USA) systems. The WHO international standard, diluted with CMV-negative WB, was used to validate the analytical performance. We used 90 WB clinical samples for comparison with the artus CMV RG PCR kit (artus assay; Qiagen, Germany). Limits of detections (LODs) in 7500 Fast and CFX96 were 367 and 479 IU/mL, respectively. The assay was linear from the LOD to 10⁶ IU/mL (R² ≥0.9886). The conversion factors from copies to IU in 7500 Fast and CFX96 were 0.95 and 1.06, respectively. Compared with the artus assay, for values <1,000 copies/mL, 100% of the samples had a variation <0.7 log₁₀ copies/mL; >1,000 copies/mL, 73.3% and 80.6% of samples in 7500 Fast and CFX96, respectively, had <0.5 log₁₀ copies/mL. The Real-Q assay is useful for quantifying CMV in WB with the two real-time PCR platforms.

Early cytomegalovirus-specific T-cell response and estimated glomerular filtration rate identify patients at high risk of infection after renal transplantation

BACKGROUND

Assessing the risk of cytomegalovirus (CMV) viremia in kidney transplant recipients (KTR) may be helpful to indicate in which patient it is worth starting antiviral treatment during preemptive strategy.

METHODS

In 40 CMV-seropositive KTR preemptively treated with ganciclovir, we used interferon (IFN)-γ ELISpot test to evaluate whether monitoring T cells directed against phosphoprotein (pp) 65 and immediate early (IE)-1 antigens could predict the onset of viremia.

RESULTS

CMV viremia occurred in 24 patients (60%) within 120 days after transplantation. Non-viremic patients had higher anti-pp65, anti-IE-1 T cells, and estimated glomerular filtration rate (eGFR) in the first 90 days after transplantation. At logistic regression, anti-pp65, anti-IE-1 T cells, and eGFR measured at day 30 were significantly associated with CMV infection. Cutoff values of 15 spot-forming cells (SFCs)/200,000 peripheral blood mononuclear cells (PBMCs) for anti-IE, 40 SFCs/200,000 PBMCs for anti-pp65, and 46.6 mL/min/1.73 m(2) for eGFR, respectively, predicted the risk of CMV infection with high sensitivity and specificity (area under the receiver operating characteristic curve >0.75). Using a classification tree model, we identified as high-risk patients those showing anti-pp65 <42 SFCs/200,000 PBMCs and eGFR <62 mL/min/1.73 m(2) , as well as anti-pp65 ≥42 and anti-IE-1 <6.5 SFCs/200,000 PBMCs.

CONCLUSION

Monitoring CMV-specific T-cell responses and eGFR in the first month post transplant can identify patients at high risk of CMV infection, for whom preemptive antiviral therapy is recommended.

Cytomegalovirus infection in renal transplantation: clinical aspects, management and the perspectives

Cytomegalovirus infection is one of most frequent infectious complications after renal transplantation, and can be classified as primo-infection, when the transmission occurs through the graft, or reactivation, when the recipient is cytomegalovirus seropositive. After transplantation, cytomegalovirus can appear as an infection, when the patient presents with evidence of viral replication without symptoms or disease, which has two clinical spectra: typical viral syndrome or invasive disease, which is a less common form. Their effects can be classified as direct, while the disease is developed, or indirect, with an increase of acute rejection and chronic allograft dysfunction risks. Diagnosis must be made based on viremia by one of the standardized methods: antigenemia or PCR, which is more sensitive. The risk factors related to infection after transplantation are the serologic matching (positive donor and negative recipient) and anti-lymphocyte antibody drugs. One of the strategies to reduce risk of disease should be chosen for patients at high risk: preemptive treatment or universal prophylaxis. Recent clinical research has described ganciclovir resistance as an emergent problem in management of cytomegalovirus infection. Two types of mutation that cause resistance were described: UL97 (most frequent) and UL54. Today, sophisticated methods of immunologic monitoring to detect specific T-cell clones against cytomegalovirus are used in clinical practice to improve the management of high-risk patients after renal transplantation.

An update on the management and prevention of cytomegalovirus infection following allogeneic hematopoietic stem cell transplantation

ABSTRACT 

A significant progress has been made in deciphering critical aspects of the biology and immunology of CMV infection in the allogeneic stem cell transplantation setting. Genetic traits predisposing to active CMV infection and CMV end-organ disease have begun to be delineated. Reliable molecular assays for CMV DNA load quantitation in body fluids have been developed. Elucidation of immune mechanisms affording control of CMV infection will help to improve the management of active CMV infection. Finally, the advent of new CMV-specific antivirals and promising vaccine prototypes as well as the development of fine procedures for large-scale ex vivo generation of functional CMV-specific T cells for adoptive T cell transfer therapies will certainly minimize the negative impact of CMV on survival in these patients.

Jeor S, Almeida-Porada G. Perivascular stromal cells as a potential reservoir of human cytomegalovirus

Human cytomegalovirus (HCMV) infection is an important cause of morbidity and mortality among both solid organ and hematopoietic stem cell transplant recipients. Identification of cells throughout the body that can potentially serve as a viral reservoir is essential to dissect mechanisms of cell tropism and latency and to develop novel therapies. Here, we tested and compared the permissivity of liver-, brain-, lung (LNG)- and bone marrow (BM)-derived perivascular mesenchymal stromal cells (MSC) to HCMV infection and their ability to propagate and produce infectious virus. Perivascular MSC isolated from the different organs have in common the expression of CD146 and Stro-1. While all these cells were permissive to HCMV infection, the highest rate of HCMV infection was seen with LNG-MSC, as determined by viral copy number and production of viral particles by these cells. In addition, we showed that, although the supernatants from each of the HCMV-infected cultures contained infectious virus, the viral copy number and the quantity and timing of virus production varied among the various organ-specific MSC. Furthermore, using quantitative polymerase chain reaction, we were able to detect HCMV DNA in BM-MSC isolated from 7 out of 19 healthy, HCMV-seropositive adults, suggesting that BM-derived perivascular stromal cells may constitute an unrecognized natural HCMV reservoir.

Updated international consensus guidelines on the management of cytomegalovirus in solid-organ transplantation

Cytomegalovirus (CMV) continues to be one of the most common infections after solid-organ transplantation, resulting in significant morbidity, graft loss, and adverse outcomes. Management of CMV varies considerably among transplant centers but has been become more standardized by publication of consensus guidelines by the Infectious Diseases Section of The Transplantation Society. An international panel of experts was reconvened in October 2012 to revise and expand evidence and expert opinion-based consensus guidelines on CMV management, including diagnostics, immunology, prevention, treatment, drug resistance, and pediatric issues. The following report summarizes the recommendations.

Recent advances in designing an effective vaccine to prevent cytomegalovirus-associated clinical diseases

It is now well over a decade since the US Institute of Medicine of the National Academy of Sciences assigned the highest priority for a vaccine to prevent congenital human CMV infection, which was subsequently endorsed by the US National Vaccine Program Office. In spite of extensive efforts over many years, successful licensure of a CMV vaccine formulation remains elusive. While the understanding of immune regulation of CMV infection in healthy virus carriers and diseased patients has dramatically improved, traditional vaccine development programs have failed to exploit this knowledge. Until recently, most efforts have concentrated on designing vaccine formulations that block CMV infection through neutralizing antibodies. However, studies carried out in various disease settings, especially in transplant patients, have clearly emphasized the importance of cellular immunity and it is indeed encouraging to see that recent CMV vaccine development programs have started to incorporate this arm of the immune system. A number of new vaccine candidates have been found to be effective in preclinical studies, and are able to induce CMV-specific immune responses in clinical studies, although firm evidence for long-term efficacy is not yet available. For successful implementation of these vaccines in clinical settings, it will be important to demonstrate that the vaccine can induce effective levels of immunity for prevention of transmission of viral infection from mother to unborn baby and thus reduce CMV-related pathogenesis. For transplant recipients, vaccine strategies should be aimed at the induction of immunity that restricts viral reactivation and limits development of disease.

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

Assessing cytomegalovirus (CMV)-specific cell-mediated immunity (CMI) represents an appealing strategy for identifying transplant recipients at risk of infection. In this study, we compared two gamma interferon-releasing assays (IGRAs), Quantiferon-CMV and CMV enzyme-linked immunosorbent spot (ELISPOT), to determine the ability of each test to predict protective CMV-specific T-cell responses. Two hundred twenty-one Quantiferon-CMV and ELISPOT tests were conducted on 120 adult kidney transplant recipients (KTRs), including 100 CMV-seropositive transplant recipients (R+) and 20 CMV-seronegative transplant recipients of a CMV-positive donor (D+/R-). As a control cohort, 39 healthy adult subjects (including 33 CMV-seropositive and 6 CMV-seronegative subjects) were enrolled. CMV IgG serology was used as a reference for both tests. In the CMV-seropositive individuals, the ELISPOT and Quantiferon-CMV assays provided 46% concordance with the serology, 12% discordance, 18% disagreement between ELISPOT or Quantiferon-CMV and the serology, and 24% gray areas when one or both tests resulted in weak positives. None of the CMV-seronegative subjects showed detectable responses in the ELISPOT or the Quantiferon-CMV test. In transplant recipients, both the ELISPOT and Quantiferon-CMV assays positively correlated with each other and negatively correlated with CMV DNAemia in a significant way (P<0.05). During the antiviral prophylaxis, all 20 D+/R- KTRs we examined displayed undetectable Quantiferon-CMV and ELISPOT results, and there was no evidence of CMV seroconversion. The receiving operator curve (ROC) statistical analysis revealed similar specificities and sensitivities in predicting detectable viremia (areas under the curve [AUC], 0.66 and 0.62 for Quantiferon-CMV and ELISPOT, respectively). ELISPOT and Quantiferon-CMV values of >150 spots/200,000 peripheral blood mononuclear cells (PBMCs) and >1 to 6 IU gamma interferon (IFN-γ) were associated with protection from CMV infection (odds ratios [OR], 5 and 8.75, respectively). In transplant recipients, the two tests displayed similar abilities for predicting CMV infection. Both the ELISPOT and Quantiferon-CMV assays require several ameliorations to avoid false-negative results.

Fully automated quantification of cytomegalovirus (CMV) in whole blood with the new sensitive Abbott RealTime CMV assay in the era of the CMV international standard

Fully standardized reproducible and sensitive quantification assays for cytomegalovirus (CMV) are needed to better define thresholds for antiviral therapy initiation and interruption. We evaluated the newly released Abbott RealTime CMV assay for CMV quantification in whole blood (WB) that includes automated extraction and amplification (m2000 RealTime system). Sensitivity, accuracy, linearity, and intra- and interassay variability were validated in a WB matrix using Quality Control for Molecular Diagnostics (QCMD) panels and the WHO international standard (IS). The intra- and interassay coefficients of variation were 1.37% and 2.09% at 5 log10 copies/ml and 2.41% and 3.80% at 3 log10 copies/ml, respectively. According to expected values for the QCMD and Abbott RealTime CMV methods, the lower limits of quantification were 104 and <50 copies/ml, respectively. The conversion factor between international units and copies (2.18), determined from serial dilutions of the WHO IS in WB, was significantly different from the factor provided by the manufacturer (1.56) (P = 0.001). Results from 302 clinical samples were compared with those from the Qiagen artus CMV assay on the same m2000 RealTime system. The two assays provided highly concordant results (concordance correlation coefficient, 0.92), but the Abbott RealTime CMV assay detected and quantified, respectively, 20.6% and 47.8% more samples than the Qiagen/artus CMV assay. The sensitivity and reproducibility of the results, along with the automation, fulfilled the quality requirements for implementation of the Abbott RealTime CMV assay in clinical settings. Our results highlight the need for careful validation of conversion factors provided by the manufacturers for the WHO IS in WB to allow future comparison of results obtained with different assays.

Prospective study on CMV-reactivations under preemptive strategy in CMV-seropositive adult liver transplant recipients

BACKGROUND

Cytomegalovirus (CMV) is a significant infectious agent after liver transplantation. To prevent CMV, most centres use prophylaxis for high-risk CMV-seronegative recipient/seropositive donor and many even for all seropositive recipients. However, pre-emptive therapy is commonly used for seropositive patients.

OBJECTIVES

A prospective, long-term follow-up of CMV-seropositive adult liver-transplant patients under pre-emptive strategy was investigated.

STUDY DESIGN

CMV-seropositive liver recipients were monitored for CMV by real-time quantitative plasma polymerase chain reaction (PCR) and received ganciclovir/valganciclovir pre-emptive therapy. The 161 patients with follow-up of >4 years were included in the study.

RESULTS

No CMV was detected in most cases 98/161 (61%), but 63/161 (39%) developed CMV-DNAaemia mean 49 days (7-183 days) after transplantation. Only 25/63 reactivations exceeded 5000 copies/ml, which was considered as cut-off for the pre-emptive treatment by the method used (median 21,500, range 5100-813300 copies/ml) and most were self-limiting, low-level DNAaemias (median 850, range 234-4000 copies/ml). Thus, low-level temporal CMV viraemia occurred in 38/161 patients (23.5%) and only 25/161 (15.5%) demonstrated significant viral loads. Recurrent CMV appeared in one patient with low-level and in 11/25 with high-level DNAaemia, only 5/11 exceeding 5000 copies/ml. CMV infections were successfully treated with ganciclovir/valganciclovir. Four patients with low and three with high DNAaemia have been retransplanted. Five patients with low and two with high DNAaemia have died subsequently. No patient or graft was lost due to CMV.

CONCLUSIONS

Most CMV-seropositive liver recipients did not develop CMV reactivation, and if reactivations occurred, most were temporal, low-level DNAaemias. Significant CMV infections were successfully treated and recurrences were rare.

CMV: Prevention, Diagnosis and Therapy

Cytomegalovirus (CMV) is the most common infection after organ transplantation and has a major impact on morbidity, mortality and graft survival. Optimal prevention, diagnosis and treatment of active CMV infection enhance transplant outcomes, and are the focus of this section. Methods to prevent CMV include universal prophylaxis and preemptive therapy; each has its merits, and will be compared and contrasted. Diagnostics have improved substantially in recent years, both in type and quality, allowing for more accurate and savvy treatment; advances in diagnostics include the development of an international standard, which should allow comparison of results across different methodologies, and assays for cellular immune function against CMV. Therapy primarily involves ganciclovir, now rendered more versatile by data suggesting oral therapy with valganciclovir is not inferior to intravenous therapy with ganciclovir. Treatment of resistant virus remains problematic, but is enhanced by the availability of multiple novel therapeutic agents.

Quantification of cytomegalovirus DNA by a fully automated real-time PCR for early diagnosis and monitoring of active viral infection in solid organ transplant recipients

BACKGROUND

Quantification of cytomegalovirus (CMV) DNA by real-time PCR is currently considered an alternative diagnostic approach for the evaluation of active infection in transplant patients. The pp65 antigenemia assay has been used as reference test for monitoring active CMV infection and guiding preemptive therapy in transplant recipients. However, this assay suffers from some limitations: need for immediate processing of the samples, labour-intensive process, lack of standardization and subjective result interpretation.

OBJECTIVES

The aim of this study was to evaluate the performance of a new commercially available real-time PCR assay coupled with a fully automated DNA extraction system (COBAS Ampliprep/COBAS Taqman CMV Test, Roche Diagnostics) for the detection of CMV-DNA in plasma comparing it with pp65 antigenemia assay for monitoring active CMV infection in solid organ transplant recipients (SOTRs).

STUDY DESIGN

A total of 266 consecutive samples from 45 SOTRs were monitored with pp65 antigenemia and in parallel with CMV-DNA quantitation by real-time PCR assay.

RESULTS

Fifty-eight samples resulted PCR-positive, 163 negative and for 45 samples the CMV-DNA values obtained were below the lower limit of quantification (<150 copies/ml); pp65 antigen was detected in 47 samples and resulted negative in 219 specimens. Concordance between the two evaluations was 76.7%; also a good correlation was observed (r=0.718). Considering the existing treatment criteria based on pp65 antigenemia evaluation corresponding to pp65 levels≥20 positive cells/200,000, preemptive therapy was administered to four asymptomatically infected patients. The corresponding cut-off value of CMV-DNA load calculated for discrimination between self-clearing infections and those requiring therapy was 2500 copies/ml (or 2275 IU/ml).

CONCLUSION

The fully automated real-time PCR from Roche provided specific and sensitive results and represented a rapid and simple assay for the evaluation and monitoring of CMV infection in SOTRs. Further studies are required to validate the threshold level for the initiation of preemptive therapy.

Determination, validation and standardization of a CMV DNA cut-off value in plasma for preemptive treatment of CMV infection in solid organ transplant recipients at lower risk for CMV infection

BACKGROUND

Valganciclovir preemptive therapy guided by the viral load is the current strategy recommended for preventing CMV disease in CMV-seropositive Solid Organ Transplant Recipients (SOTR) at lower risk for developing CMV infection. However, universal viral load cut-off has not been established for initiating therapy.

OBJECTIVES

Our goal was to define and validate a standardized cut-off determined in plasma by real-time PCR assay for initiating preemptive therapy in this population.

STUDY DESIGN

A prospective cohort study of consecutive cases of CMV-seropositive SOTR was carried out. The cut-off value was determined in a derivation cohort and was validated in the validation cohort. Viral loads were determined using the Quant CMV LightCycler 2.0 real-time PCR System (Roche Applied Science) and results were standardized using the WHO International Standard for human CMV.

RESULTS

A viral load of 3983 IU/ml (2600 copies/ml) was established as the optimal cut-off for initiating preemptive therapy in a cohort of 141 patients with 982 tests and validated in a cohort of 252 recipients with a total of 2022 test. This cut-off had a 99.6% NPV indicating that the great majority of patients at lower risk will not develop CMV disease without specific antiviral therapy. The high sensitivity and specificity (89.9% and 88.9%, respectively) and the relatively small numbers of patients with CMV disease confirm that real-time PCR was optimal.

CONCLUSIONS

We have established a cut-off viral load for starting preemptive therapy for CMV-seropositive SOT recipients. Our results emphasized the importance of a mandatory follow-up protocol for CMV-seropositive patients receiving preemptive treatment.

[Lights and shadows of cytomegalovirus infection in solid organ transplantation]

Cytomegalovirus (CMV) develops in 30-80% of patients undergoing solid organ transplantation (SOT). The incidence and presence of symptomatic disease varies depending on the type of transplant, the presence of associated risk factors, the intensity of immunosuppression, and the prevention strategies used. The impact of CMV on SOT is due not only to the effects of CMV disease per se, but also to its multiple indirect effects resulting from its immunomodulatory role and immunoactivation caused by viral latency. The two prophylactic strategies used (universal prophylaxis and preemptive therapy) are equally useful. Both strategies have advantages and disadvantages, and uncertainties remain on the populations that should receive prophylaxis and for how long. Viral monitoring to detect CMV infection is important for diagnosis, prognosis and evaluation of treatment response. The new real-time polymerase chain reaction techniques have provided numerous advantages but standardization remains an issue and common reference values are required. Specific anti-CMV drugs are available but issues such as the role of valganciclovir versus ganciclovir, the development of resistances and optimal treatment length are still being debated. Complementary therapy with mTOR inhibitors and vaccine strategies against CMV are alternatives for which conclusive data are lacking.

Detection of active human cytomegalovirus by the promyelocytic leukemia body assay in cultures of PBMCs from patients undergoing hematopoietic stem cell transplantation

A novel detection system was established previously for cells infected with the human cytomegalovirus (HCMV) in vitro that utilizes the unique IE1-dependent nuclear dispersion of promyelocytic leukemia (PML) bodies early in the HCMV replication cycle. This assay system, designated "the PML assay," makes use of the GFP-PML-expressing cell line SE/15, and allows real-time monitoring of infected cells by fluorescence microscopy without any staining procedures. A rapid and quantitative drug susceptibility testing was developed for low-titer clinical isolates propagated in fibroblasts in vitro. The present study sought to exploit the PML assay for evaluating in vivo status of HCMV without virus isolation. Progeny viruses were detected directly from peripheral blood mononuclear cells (PBMCs) infected in vivo obtained from hematopoietic stem cell transplantation recipients. The overall positivity of the PML assay tended to correlate with the levels of genomic DNA. Direct phenotypic susceptibility testing detected one ganciclovir (GCV)-resistant case among 19 samples, which was confirmed further by genomic and plaque reduction assays. However, in another patient with the sequence-proven mutant confirmed by sequencing, the progeny viruses exhibiting GCV-resistance were not detected. Studies on the isolated virus from the latter patient suggested the possibility that replication efficiency may differ between PBMCs and lesions infected in vivo, which may hamper the detection of GCV-resistant viruses by the PML assay, at least in this case. Taken together, the PML assay is sufficiently sensitive to monitor replication-competent HCMV directly from PBMCs infected in vivo, and provides a novel tool for comparing the characteristics of HCMV strains infected in vivo.

Human cytomegalovirus-specific T-cell immune reconstitution in preemptively treated heart transplant recipients identifies subjects at critical risk for infection

Human cytomegalovirus (CMV) infection represents a major threat for heart transplant recipients (HTXs). CMV-specific T cells effectively control virus infection, and thus, assessment of antiviral immune recovery may have clinical utility in identifying HTXs at risk of infection. In this study, 10 CMV-seropositive (R(+)) pretransplant patients and 48 preemptively treated R(+) HTXs were examined before and after 100 days posttransplant. Preemptive treatment is supposed to favor the immune recovery. CMV DNAemia and gamma interferon enzyme-linked immunosorbent spot (ELISPOT) assay were employed to assess the viremia and immune reconstitution. HTXs could be categorized into three groups characterized by high (>100), medium (50 to 100), and low (<50) spot levels. Early-identified high responders efficiently controlled the infection and also maintained high immunity levels after 100 days after transplant. No episodes of grade ≥2R rejection occurred in the high responders. Midresponders were identified as a group with heterogeneous trends of immune reconstitution. Low responders were 41% and 21% of HTXs before and after 100 days posttransplant, respectively. Low responders were associated with a higher incidence of infection. The effect of viremia on immune recovery was investigated: a statistically significant inverse correlation between magnitude of viremia and immune recovery emerged; in particular, each 10-fold increase in viremia (>4 log(10) DNAemia/ml) was associated with a 36% decrease of the ELISPOT assay spot levels. All episodes of high viremia (>4 log(10) DNAemia/ml) occurred from 1 to 60 days after transplant. Thus, the concomitant evaluation of viremia and CMV immune reconstitution has clinical utility in identifying HTXs at risk of infection and may represent a helpful guide in making therapeutic choices.

Real-time PCR versus viral culture on urine as a gold standard in the diagnosis of congenital cytomegalovirus infection

BACKGROUND

Cytomegalovirus (CMV) infection is the most common cause of congenital infection. Whereas CMV PCR has replaced viral culture and antigen detection in immunocompromised patients because of higher sensitivity, viral culture of neonatal urine is still referred to as the gold standard in the diagnosis of congenital CMV infection.

OBJECTIVE

To compare real-time CMV PCR with shell vial culture on urine in the diagnosis of congenital CMV, in a multicenter design.

STUDY DESIGN

A series of neonatal urines (n=340), received for congenital CMV diagnostics and routinely assessed with shell vial CMV culture, was retrospectively tested by real-time CMV PCR.

RESULTS

The proportion of newborns found to be congenitally infected by real-time CMV PCR was 8.2% (28/340, 95%CI 5.6-11.8%), and 7.4% (25/340, 95%CI 4.9-10.8%) by rapid culture. When considering rapid culture as reference, real-time PCR was highly sensitive (100%), whereas sensitivity of rapid culture was 89.3% when considering real-time PCR as reference.

CONCLUSIONS

Our results, supported by analytical and clinical data on CMV DNA detection in neonatal urine, suggest enhanced sensitivity of recent PCR techniques when compared to viral culture. There is considerable rationale to favor real-time CMV PCR as a gold standard in the diagnosis of congenital CMV infection. A large-scale study combining both laboratory and clinical data is required to determine the exact time frame for sampling of neonatal urine when using real-time PCR.

Dissecting the requirements for maintenance of the CMV-specific memory T-cell pool

Cytomegalovirus (CMV) infection promotes a broad T-cell response, with the resulting memory cells displaying diverse phenotypes. CMV establishes lifelong persistence/latency, and it is thought that viral antigens expressed during this period may regulate the expansion and/or maintenance of "inflationary" CD8 T-memory populations that display an effector memory phenotype. We show here that mouse CMV (MCMV)-specific inflationary memory T cells do not decrease in number after thymectomy, indicating that recent thymic emigrants are not strictly required for their maintenance. Furthermore, persistent MCMV replication in the salivary gland does not significantly impact the T-cell memory compartment, as surgical removal did not alter its composition. These results shed light upon the mechanisms required for maintenance of the large, MCMV-specific T-cell memory pool.

Comparison of the performance of polymerase chain reaction and pp65 antigenemia for the detection of human cytomegalovirus in immunosuppressed patients

INTRODUCTION

Human cytomegalovirus (HCMV) is often reactive in latently infected immunosuppressed patients. Accordingly, HCMV remains one of the most common infections following solid organ and hemopoietic stem cell transplantations, resulting in significant morbidity, graft loss and occasional mortality. The early diagnosis of HCMV disease is important in immunosuppressed patients, since in these individuals, preemptive treatment is useful. The objective of this study was to compare the performance of the in-house qualitative polymerase chain reaction (PCR) and pp65 antigenemia to HCMV infection in immunosuppressed patients in the Hospital de Clínicas of Porto Alegre (HCPA).

METHODS

A total of 216 blood samples collected between August 2006 and January 2007 were investigated.

RESULTS

Among the samples analyzed, 81 (37.5%) were HCMV-positive by PCR, while 48 (22.2%) were positive for antigenemia. Considering antigenemia as the gold standard, sensitivity, specificity, positive predictive values and negative predictive values for PCR were 87.5%, 76.8%, 51.8% and 95.5% respectively.

CONCLUSIONS

These results demonstrated that qualitative PCR has high sensitivity and negative predictive value (NPV). Consequently PCR is especially indicated for the initial diagnosis of HCMV infection. In the case of preemptive treatment strategy, identification of patients at high-risk for HCMV disease is fundamental and PCR can be useful tool.

"pp65 antigenemia and real time polymerase chain reaction (PCR) based-study to determine the prevalence of human cytomegalovirus (HCMV) in kidney donors and recipients with follow-up studies"

Background

The present study was undertaken to determine the rate of occurrence of Human cytomegalovirus (HCMV) among kidney transplant recipients and donors by application of direct detection methods and to understand HCMV infection/disease development among transplanted patients as a prospective study.

Results

Peripheral blood samples collected from 76 kidney donors and 76 recipients from September 2007 to August 2009 were subjected to pp65 antigenemia and Quantitative real-time PCR (qRT-PCR) assays. Data were analyzed under Group A, B and C. Group A was further divided into sub-groups I, II, III, IV, and V for better understanding. Three, one and two donors in sub-group I, III, IV of Group A tested positive for real time PCR respectively. One recipient from group III tested positive for HCMV by qRT- PCR prior transplantation and remained positive one month post-transplantation. Three other recipients, tested negative prior to transplantation became positive a month after transplantation. Group B consisted of 18 donor-recipient pairs and one of the donor tested positive for HCMV by qRT-PCR. Eight recipients tested positive for HCMV one month after transplantation. The pp65 positivity and HCMV DNA load was high among group C recipients who mostly had symptoms of active disease. Significantly high values of pp65 antigenemia were observed among recipients of sub-group II (non-parametric chi-square test p = 0.007). Positive correlation between pp65 antigenemia and qRT-PCR value was observed. Thirty three of the recipients with disease treated with Valgancyclovir showed improved clinical outcome.

Conclusion

Our study showed that a significant proportion of kidney recipients develop HCMV infection following renal transplantation in spite of the absence of HCMV among donors. pp65 antigenemia assay and qRT- PCR methods can be applied to detect HCMV among kidney donors and recipients to monitor development of disease and these assays were predicative of HCMV infection among them. Clinical resistant to valganciclovir was not observed.

Signature profiles of CMV-specific T-cells in patients with CMV reactivation after hematopoietic SCT

Depletion of cellular immunity as a consequence of conditioning before allogeneic hematopoietic SCT (HSCT) frequently results in CMV reactivation, which may in turn lead to life-threatening infections and require timely antiviral treatment. We have investigated the functional signatures of CMV-specific CD4+ and CD8+ T-cells in 191 samples from 118 individuals. We compared healthy donors with both patients with high and undetectable viral loads, and those who controlled and did not control their CMV reactivations. Polychromatic flow-cytometric measurements of CD154 (CD40L), intracellular cytokines (IFNγ, IL2) and a degranulation marker (CD107a) allowed us to assess the functional status of various T-cells simultaneously. We found that dual IFNγ/IL2-producing CD8+ T-cells were present in patients controlling their CMV reactivations but absent from non-controllers. CD8+ T-cells that produce only IFNγ were the most abundant subtype, but they most likely represent non-protective memory cells. Distinct functional signatures were examined by hierarchical clustering, and this revealed that, unlike polyfunctional CD8+ T-cells, CD8+ T-cells that produce IFNγ alone were not functioning in concert with other subsets. In conclusion, our study revealed functional signatures that may be useful for immune monitoring, and it could change the interpretation of previous studies that assessed only IFNγ.