Clinical usefulness of plasma quantitative polymerase chain reaction assay: diagnosis of cytomegalovirus infection in kidney transplant recipients

Cytomegalovirus infection after renal transplantation

Renal transplant patients show a high prevalence of cytomegalovirus (CMV) infection after the procedure. This study was conducted to assess the prevalence and factors associated with the incidence of CMV infection among renal transplant patients. A total of 100 patients were recruited in this study. The CMV load in the blood of each patient was assessed using the technique of polymerase chain reaction (PCR). The serostatus of all recipients and donors was examined preoperatively and those of the recipients again postoperatively. The association of CMV load was assessed with the following factors: age, gender, alanine aminotransferase (ALT) and serum creatinine levels, types of immunosuppressive and induction regimens, preoperative diabetes status, and serological virologic response (SVR) at 12 weeks postoperatively. Our findings showed that CMV incidence was significantly higher in middle-aged patients (62 of 66 patients, 93.9%; p=0.0001). Furthermore, about 88.2% of patients induced by anti-thymocyte globulin (ATG) showed a high viral load, significantly higher than the proportion of CMV-positive patients induced by basiliximab (p=0.001). In addition, a higher proportion of CMV-negative recipients who received the graft from CMV-positive donors and vice-versa were CMV-positive postoperatively. Administration of Valcyte 450 showed 100% efficiency in decreasing the CMV load in the patients. Among all the assessed factors, only the age of the recipients, type of induction therapy used, and the preoperative serostatus of both donors and recipients were significantly associated with the postoperative CMV incidence among the patients.

Clinical validation of an in-house quantitative real time PCR assay for cytomegalovirus infection using the 1st WHO International Standard in kidney transplant patients

Introduction:

Cytomegalovirus (CMV) is one of the most common agents of infection in solid organ transplant patients, with significant morbidity and mortality.

Objective:

This study aimed to establish a threshold for initiation of preemptive treatment. In addition, the study compared the performance of antigenemia with qPCR results.

Study design:

This was a prospective cohort study conducted in 2017 in a single kidney transplant center in Brazil. Clinical validation was performed by comparing in-house qPCR results, against standard of care at that time (Pp65 CMV Antigenemia). ROC curve analysis was performed to determine the ideal threshold for initiation of preemptive therapy based on the qPCR test results.

Results:

Two hundred and thirty two samples from 30 patients were tested with both antigenemia and qPCR, from which 163 (70.26%) were concordant (Kappa coefficient: 0.435, p<0.001; Spearman correlation: 0.663). PCR allowed for early diagnoses. The median number of days for the first positive result was 50 (range, 24-105) for antigenemia and 42 (range, 24-74) for qPCR (p<0.001). ROC curve analysis revealed that at a threshold of 3,430 IU/mL (Log 3.54), qPCR had a sensitivity of 97.06% and a specificity of 74.24% (AUC 0.92617 ± 0.0185, p<0.001), in the prediction of 10 cells/10⁵ leukocytes by antigenemia and physician's decision to treat.

Conclusions:

CMV Pp65 antigenemia and CMV qPCR showed fair agreement and a moderate correlation in this study. The in-house qPCR was revealed to be an accurate method to determine CMV DNAemia in kidney transplant patients, resulting in positive results weeks before antigenemia.

Outcome Comparison between Low-Dose Rabbit Anti-Thymocyte Globulin and Basiliximab in Low-Risk Living Donor Kidney Transplantation

The objective of this study was to compare outcomes between basiliximab and low-dose r-ATG in living donor kidney transplantation recipients with low immunological risk. Patients in the low-dose r-ATG group received 1.5 mg/kg of r-ATG for 3 days (total 4.5 mg/kg). Graft survival, patient survival, acute rejection, de novo donor specific antibody (DSA), estimated glomerular filtration rate (e-GFR) changes, and infection status were compared. Among 268 patients, 37 received r-ATG, and 231 received basiliximab. There was no noticeable difference in the graft failure rate (r-ATG vs. basiliximab: 2.7% vs. 4.8%) or rejection (51.4% vs. 45.9%). de novo DSA was more frequent in the r-ATG group (11.4% vs. 2.4%, p = 0.017). e-GFR changes did not differ noticeably between groups. Although most infections showed no noticeable differences between groups, more patients in the r-ATG group had cytomegalovirus (CMV) antigenemia and serum polyomavirus (BK virus) (73.0% vs. 51.9%, p = 0.032 in CMV; 37.8% vs. 15.6%, p = 0.002 in BK), which did not aggravate graft failure. Living donor kidney transplantation patients who received low-dose r-ATG and patients who received basiliximab showed comparable outcomes in terms of graft survival, function, and overall infections. Although CMV antigenemia, BK viremia were more frequent in the r-ATG group, those factors didn’t change the graft outcomes.

Effects of Granulocyte and Monocyte Adsorptive Apheresis in Renal Transplantation Recipients With Concomitant Cytomegalovirus Infection

BACKGROUND

Granulocyte and monocyte adsorptive apheresis (GMAA) is widely used as a treatment for active ulcerative colitis (UC) in Japan. Much attention has been paid to the possibility of GMAA for the treatment and control of cytomegalovirus (CMV) reactivation in patients with refractory UC and concomitant CMV infection. In this study, the effects of the combination of GMAA and antiviral therapy were examined in renal transplant recipients with concomitant CMV infection.

METHODS

Combination therapy of GMAA and antiviral drugs was performed 9 times in 7 renal transplant recipients with concomitant CMV infection. Four of the cases were positive for CMV-IgG, and 3 were negative. The clinical presentation of CMV infection was viremia in 6 cases and disease (CMV retinitis) in 1 case. CMV infection was diagnosed by using an antigenemia assay (C7-HRP). GMAA session was performed once, and the duration of the session was 120 min. Immediately after the GMAA session, ganciclovir was administered at 5 mg/kg/body weight. CMV infection was monitored based on C7-HRP and CMV-DNA in the peripheral blood samples.

RESULTS

All cases became negative for C7-HRP and CMV-DNA within 21 days (median, 14 days; range, 3-21 days) and 17 days (median, 6 days; range, 3-17 days), respectively, after starting the combination therapy. No side effects of GMAA were observed.

CONCLUSIONS

This case series found that GMAA in combination with antiviral drugs may shorten the duration of treatment against CMV infection in renal transplant recipients. Further studies in a larger number of patients are required to confirm these results.

Targeted preemptive therapy according to perceived risk of CMV infection after kidney transplantation

Background

Methods

Results

Conclusion

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.

Comparison of quantitation of cytomegalovirus DNA by real-time PCR in whole blood with the cytomegalovirus antigenemia assay

Background

Quantitation of cytomegalovirus (CMV) DNA using real-time PCR has been utilized for monitoring CMV infection. However, the CMV antigenemia assay is still the 'gold standard' assay. There are only a few studies in Korea that compared the efficacy of use of real-time PCR for quantitation of CMV DNA in whole blood with the antigenemia assay, and most of these studies have been limited to transplant recipients.

Method

479 whole blood samples from 79 patients, falling under different disease groups, were tested by real-time CMV DNA PCR using the Q-CMV real-time complete kit (Nanogen Advanced Diagnostic S.r.L., Italy) and CMV antigenemia assay (CINA Kit, ArgeneBiosoft, France), and the results were compared. Repeatedly tested patients were selected and their charts were reviewed for ganciclovir therapy.

Results

The concordance rate of the two assays was 86.4% (Cohen's kappa coefficient value=0.659). Quantitative correlation between the two assays was a moderate (r=0.5504, P<0.0001). Among 20 patients tested repeatedly with the two assays, 13 patients were transplant recipients and treated with ganciclovir. Before treatment, CMV was detected earlier by real-time CMV DNA PCR than the antigenemia assay, with a median difference of 8 days. After treatment, the antigenemia assay achieved negative results earlier than real-time CMV DNA PCR with a median difference of 10.5 days.

Conclusions

Q-CMV real-time complete kit is a useful tool for early detection of CMV infection in whole blood samples in transplant recipients.

Analytical characterization of an assay designed to detect and identify diverse agents of disseminated viral infection

BACKGROUND

Diverse viruses often reactivate in or infect cancer patients, patients with immunocompromising infections or genetic conditions, and transplant recipients undergoing immunosuppressive therapy. These infections can disseminate, leading to death, transplant rejection, and other severe outcomes.

OBJECTIVES

To develop and characterize an assay capable of inclusive and accurate identification of diverse potentially disseminating viruses directly from plasma specimens.

STUDY DESIGN

We developed a PCR/electrospray ionization mass spectrometry (PCR/ESI-MS) assay designed to simultaneously detect and identify adenovirus, enterovirus, polyomaviruses JC and BK, parvovirus B19, HSV-1, HSV-2, VZV, EBV, CMV, and herpesviruses 6-8 in plasma specimens. The assay performance was characterized analytically, and the results from clinical plasma samples were compared to the results obtained from single-analyte real time PCR tests currently used in clinical practice.

RESULTS

The assay demonstrated sensitivity and specificity to diverse strains of the targeted viral families and robustness to interfering substances and potentially cross reacting organisms. The assay yielded 94% sensitivity when testing clinical plasma samples previously identified as positive using standard-of-care real-time PCR tests for a single target virus (available samples included positive samples for 11 viruses targeted by the assay).

CONCLUSIONS

The assay functioned as designed, providing simultaneous broad-spectrum detection and identification of diverse agents of disseminated viral infection. Among 156 clinical samples tested, 37 detections were made in addition to the detections matching the initial clinical positive results.

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.

Cytomegalovirus in solid organ transplantation: epidemiology, prevention, and treatment

Cytomegalovirus (CMV) is one of the most important pathogens that infect solid organ transplant recipients. CMV is associated with increased morbidity and mortality in this population as a result of its numerous direct and indirect effects. Prevention strategies consist of preemptive therapy and antiviral prophylaxis, and the choice of which preventive approach to implement should be guided by advantages and drawbacks related to the population being managed. There are differences in the approaches to the laboratory diagnosis and treatment of CMV infection and disease depending on assay availability, clinical presentation, disease severity, and specific transplant populations. In this article, the authors aim to summarize recent publications and updates in the epidemiology, diagnosis, prevention, and treatment of CMV infection in solid organ transplant recipients during the past year, including a brief review of future directions in the field.