Quantitative PCR in the diagnosis of CMV infection and in the monitoring of viral load during the antiviral treatment in renal transplant patients

Advances and Challenges in Cytomegalovirus Detection Methods for Liver Transplant Donors

Cytomegalovirus (CMV) infection is a highly prevalent opportunistic infection among liver transplant recipients. When the liver donor is infected with CMV, there is a risk of transmission to the recipient, leading to CMV infection. To improve the postoperative outcome of liver transplantation, it is crucial to shift the focus of CMV detection to the donor and achieve early diagnosis, as well as implement effective preventative and therapeutic measures. However, the commonly used CMV detection methods in the past had limitations that prevented their early and accurate diagnosis in liver transplant donors. This review focuses on the latest advancements in CMV detection methods that can potentially be applied to liver transplant donors. The objective is to compare and evaluate their clinical utility, thereby providing guidance and support for rapid and accurate diagnosis of CMV infection in the clinic. The clustered regularly interspaced short palindromic repeats-associated proteins (CRISPR-Cas) system-based assay emerges as a promising method for detecting the virus, offering great prospects for early and expedient CMV infection diagnosis in clinical settings.

Prevention and management of human cytomegalovirus in pediatric HSCT recipients: A review

Cytomegalovirus (CMV), like other herpesviruses, has the unique ability to establish latent infection with subsequent reactivation during periods of stress and immunosuppression. Herpesviruses cause potentially devastating disease, particularly in hematopoietic stem cell transplant (HSCT) recipients. CMV is especially of concern in HSCT recipients given the high community seroprevalence, high risk of reactivation and high risk of transmission from HSCT donors to recipients causing primary infection after transplantation. The risk of CMV infection and severity of CMV disease varies depending on the underlying disease of the HSCT recipient, donor and recipient CMV status prior to HSCT, type of conditioning therapy in preparation for HSCT, allogeneic versus autologous HSCT, donor graft source, timing of infection in relation to HSCT, and other patient comorbidities. Different strategies exist for prevention (e.g., preemptive therapy vs. universal prophylaxis) as well as management of CMV disease (e.g., antiviral therapy, augmenting immune reconstitution, cytotoxic T-cell therapy). The purpose of this narrative review is to discuss diagnosis, prevention, and management of CMV infection and disease at different stages of HSCT, including key points illustrated through presentations of complex cases and difficult clinical scenarios. Traditional and novel strategies for CMV management will be discussed in the context of these unique clinical cases.

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.

Cause of acute encephalitis/encephalopathy in Japanese children diagnosed by a rapid and comprehensive virological detection system and differences in their clinical presentations

BACKGROUND

Acute encephalitis/encephalopathy (AE/E) is a rare and severe complication of common childhood infections; however, a treatment strategy based on clinical and pathological evidence has not been established.

METHODS

The clinical data and aetiological results using a rapid and comprehensive virological detection system of 62 Japanese children diagnosed with AE/E from 2010 to 2014 were collected. We assessed clinical differences between causes and effectiveness of our multiplex PCR system to establish a pathogen-based treatment strategy for AE/E.

RESULTS

Suspected causes were detected in 84% of patients, and our multiplex PCR system contributed to diagnosing 38% of the patients. Furthermore, a negative virus PCR might be important for inferring underlying disease. Most cases were triggered by human herpes virus (HHV) 6/7 (32%) and influenza virus (24%). The causes of AE/E depended on age (p=0.00089) but not on sex (p=0.94). The median age of HHV6/7-associated AE/E was 2.3years, which is lower than the median ages of AE/E associated with other viruses. Major initial treatments were pulse steroid therapy (83.9%) and acyclovir (71%). Most of the patients in this study had good prognoses: 77% recovered without neurological sequalae.

CONCLUSIONS

Our virological detection system was useful for detecting the cause of AE/E, and may also contribute to construction of pathogen-based treatment strategies for AE/E. Our data indicated the possibility that early intervention with pulse steroid therapy could be effective for treating AE/E. Further investigation for selection of antiepileptic drugs and additional therapies might be required to prevent progression of AE/E.

Clinical utility of viral load in management of cytomegalovirus infection after solid organ transplantation

The negative impact of cytomegalovirus (CMV) infection on transplant outcomes warrants efforts toward improving its prevention, diagnosis, and treatment. During the last 2 decades, significant breakthroughs in diagnostic virology have facilitated remarkable improvements in CMV disease management. During this period, CMV nucleic acid amplification testing (NAT) evolved to become one of the most commonly performed tests in clinical virology laboratories. NAT provides a means for rapid and sensitive diagnosis of CMV infection in transplant recipients. Viral quantification also introduced several principles of CMV disease management. Specifically, viral load has been utilized (i) for prognostication of CMV disease, (ii) to guide preemptive therapy, (iii) to assess the efficacy of antiviral treatment, (iv) to guide the duration of treatment, and (v) to indicate the risk of clinical relapse or antiviral drug resistance. However, there remain important limitations that require further optimization, including the interassay variability in viral load reporting, which has limited the generation of standardized viral load thresholds for various clinical indications. The recent introduction of an international reference standard should advance the major goal of uniform viral load reporting and interpretation. However, it has also become apparent that other aspects of NAT should be standardized, including sample selection, nucleic acid extraction, amplification, detection, and calibration, among others. This review article synthesizes the vast amount of information on CMV NAT and provides a timely review of the clinical utility of viral load testing in the management of CMV in solid organ transplant recipients. Current limitations are highlighted, and avenues for further research are suggested to optimize the clinical application of NAT in the management of CMV after transplantation.

Absence of Epstein-Barr and cytomegalovirus infection in neuroblastoma cells by standard detection methodologies

Indications exist in the scientific literature that infection with human herpes family viruses may contribute to the pathogenesis of neuroblastoma (NB). However, systematic investigations regarding viral presence in NB cells have been scarcely reported. Here, the presence of DNA from Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) was assessed by PCR in 12 NBs, supplemented with RNA in situ hybridization, immunohistochemical detection, and high-throughput DNA sequencing. These standard methods did not detect infection by EBV or HCMV in NB cells in any tumor, while occasional immune cells were positive for EBV RNA or HCMV protein in four cases.

Cytomegalovirus and herpes simplex virus effect on the prognosis of mechanically ventilated patients suspected to have ventilator-associated pneumonia

OBJECTIVE

Cytomegalovirus (CMV) and herpes simplex virus (HSV) are common viruses that can affect critically ill patients who are not immunocompromised. The aim of this study was to determine whether the identification of CMV and/or HSV in mechanically ventilated critically ill patients suspected of having pneumonia was associated with an increased mortality.

DESIGN

Prospective epidemiological study.

SETTING

Medical intensive care unit of a tertiary medical center.

PATIENTS

Ninety-three patients with suspected pneumonia.

INTERVENTIONS

Patients with suspected pneumonia had bronchoalveolar lavage and blood samples taken to confirm the diagnosis. Antigenemia was used to detect CMV in the blood. Bronchoalveolar lavage samples were submitted to testing using quantitative real-time Polymerase Chain Reaction.

MEASUREMENTS AND MAIN RESULTS

We identified 22 patients with a CMV infection, 26 patients with an HSV infection and 45 patients without CMV or HSV infection (control group). Mortality at day 60 was higher in patients with a CMV infection than in patients from the control group (55% vs. 20%, P<0.01). Mortality at day 60 was not significantly increased in the group with HSV infection. Duration of ICU stay and ICU mortality were significantly higher in patients with CMV infections when compared to patients from the control group, whereas ventilator free days were significantly lower in patients with CMV infections when compared to patients from the control group.

CONCLUSIONS

In critically ill patients, a CMV infection is associated with an increased mortality. Further interventional studies are needed to evaluate whether treatment could improve the prognosis.

Correlation and clinical utility of pp65 antigenemia and quantitative polymerase chain reaction assays for detection of cytomegalovirus in pediatric renal transplant patients

qPCR and pp65 antigenemia assays are used to monitor CMV infection in renal transplant recipients, but correlation of assays in a pediatric population has not been evaluated. Paired CMV real-time qPCR and pp65 antigenemia tests from 882 blood samples collected from 115 pediatric renal transplant recipients were analyzed in this retrospective cohort study for the strength of association and clinical correlates. The assays correlated well in detecting infection (κ = 0.61). Higher qPCR values were demonstrated with increasing levels of antigenemia (p < 0.01). Discordant test results were associated with antiviral treatment (OR 4.33, p < 0.01) and low-level viremia, with odds of concordance increasing at higher qPCR values (OR 3.67, p < 0.01), and no discordance occurring above 8500 genomic equivalents/mL. Among discordant samples, neither test preceded the other in detecting initial infection or in returning to negative while on treatment. Only two cases of disease occurred during the two-yr study period. With strong agreement in the detection of CMV infection, either qPCR or pp65 antigenemia assays can be used effectively for monitoring pediatric renal transplant patients for both detection and resolution of infection.

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

BACKGROUND

Preemptive therapy is used to prevent cytomegalovirus (CMV) disease in transplant recipients. The CMV antigenemia assay, which has been commonly used as a predictive marker for preemptive therapy, requires intensive labor and immediate processing. We compared the cutoff value of plasma CMV polymerase chain reaction (PCR) with CMV antigenemia in kidney transplant recipients.

METHODS

We compared two diagnostic methods for CMV infection in kidney transplant recipients: quantitative PCR (qPCR) versus antigenemia. We evaluated the optimal cutoff value of plasma CMV qPCR by using receiver-operating characteristic curves for specific antigenemia values. All kidney transplant recipients from January 2004 to January 2005 were enrolled and followed with CMV antigenemia and plasma CMV qPCR.

RESULTS

The analyses were performed on 899 samples collected from 111 patients in the early posttransplant period, matching 84.1% of patients for the results of CMV antigenemia and plasma CMV qPCR. For patients with symptomatic CMV infection and disease, who showed ≥25 positive cells in the antigenemia assay, the cutoff value for qPCR was 17.8 copies/μL with a sensitivity of 97.1%, a specificity of 89.1%, and a positive predictive value of 26.6%.

CONCLUSIONS

Diagnostic assays for CMV such as CMV antigenemia and quantitative plasma PCR, showed similar diagnostic values. They are the methods of choice for the diagnosis and monitoring of active CMV infection after kidney transplantation. However, because of the relatively low positive predictive value of qPCR, this test may lead to unnecessary preemptive treatment in kidney transplant recipients.

Human cytomegalovirus and kidney transplantation: a clinician's update

Infection with human cytomegalovirus (CMV) is an important cause of morbidity and mortality in kidney transplant recipients. CMV disease is diagnosed based on the detection of viral replication by phosphoprotein 65 antigenemia or CMV DNA polymerase chain reaction in combination with typical signs and symptoms. Risk factors include CMV-seronegative recipients receiving a CMV-seropositive transplant, older donor age, exposure to cyclosporine and/or antilymphocyte antibody, rejection episodes, and impaired transplant function. Current preventive strategies in kidney transplant recipients include pre-emptive therapy with valganciclovir or intravenous ganciclovir and universal prophylaxis with valacyclovir, valganciclovir, or ganciclovir for 3-6 months after kidney transplantation and for 1-3 months after treatment with antilymphocyte antibody. Established disease should be treated using either intravenous ganciclovir or oral valganciclovir until CMV replication can no longer be detected. In addition to direct effects, CMV infection also induces a wide range of indirect effects, such as decreased transplant and recipient survival and susceptibility to rejection and opportunistic infections. In this review, we highlight the most relevant topics on CMV and kidney transplantation based on current evidence and guidelines.

Increased mortality in long-term intensive care patients with active cytomegalovirus infection

OBJECTIVE

To determine the prevalence and impact on patient outcome of active human cytomegalovirus infections in patients with prolonged treatment in an intensive care unit.

DESIGN

Retrospective analysis of stored plasma samples.

SETTING

Anesthesiological intensive care unit of a university hospital.

PATIENTS

All 138 patients treated for at least 14 days (of a total of 4940 patients admitted during the study period). Immunocompromised patients and patients with inconclusive results for cytomegalovirus DNA were excluded.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Stored plasma samples of patients with prolonged intensive care unit stay were tested for cytomegalovirus DNA. Sixty-four of 255 evaluable samples from 99 immunocompetent patients tested cytomegalovirus DNA-positive with a mean DNA concentration of 8,600 genome equivalents per milliliter. Active cytomegalovirus infection was diagnosed by reproducibly positive results in 35 patients (35%). Only one case had been diagnosed clinically. Patients with and without active cytomegalovirus infection were not significantly different in parameters, such as age, sex, admission category, source of admission, or comorbidities. Even review of specific surgical procedures or the use of a heart-lung-machine showed no significant differences between the groups. The mortality rate in patients with cytomegalovirus infection was significantly increased (28.6% vs. 10.9%, p = 0.048), and surviving patients had a longer intensive care unit stay (32.6 vs. 22.1 days, p <0.001).

CONCLUSIONS

Active cytomegalovirus infection is a frequent but seldom diagnosed finding in surgical patients with prolonged intensive care unit stay, which is associated with increased mortality and prolonged intensive care unit stay of surviving patients.

Prediction of cytomegalovirus (CMV) plasma load from evaluation of CMV whole-blood load in samples from renal transplant recipients

In a prospective cohort of 82 renal transplant recipients, we evaluated the capacity of the cytomegalovirus (CMV) load in whole blood (WB) to predict the plasma CMV load, aiming to identify active CMV infections by using WB samples only and to deduce a WB threshold. Using quantitative real-time PCR, a total of 1,474 WB samples were assayed, of which 279 were positive for CMV, and 140 out of the 276 paired plasma samples tested positive. Thirty (36.6%) patients presented with at least one positive plasma PCR result, and 21 infection episodes (19 patients) required curative treatment (median follow-up time, 12 months). When the plasma CMV load was >500 copies/ml (n = 70), more than 94% (95% confidence interval, 86.0%, 98.4%) of WB samples had >500 copies/ml. Two prediction models were built: log(10) plasma viral load (VL) was calculated as -0.3777 + 0.9342 x log(10) WB VL and as -0.3777 + 0.8563 x log(10) WB VL for patients with and without treatment, respectively. In the validation sample (578 routine samples), 77.2% of the observed and expected plasma viral loads were concordant (95% confidence intervals, 73.5 and 80.5%). According to the model, the plasma viral load was >500 copies/ml when the WB load was >3,170 or >4,000 copies/ml in patients with or without treatment, respectively. WB seems to be an appropriate candidate for routine CMV monitoring of transplant recipients by using a single assay.

Laboratory diagnosis of cytomegalovirus infection and disease in immunocompromised patients

PURPOSE OF REVIEW

To review new developments in PCR technology as they apply to detecting cytomegalovirus viremia and pneumonia, recent advances in detecting CMV resistance to antivirals and assays of specific CMV lymphocyte function.

RECENT FINDINGS

This review summarizes the attempts to use real time PCR for cytomegalovirus deoxyribonucleic acidemia and to compare it to conventional PCR and antigenemia, it also reviews the use of quantitative PCR on bronchoalveolar lavage to assist in the diagnosis of CMV pneumonia. Phenotypic assays of susceptibility in tissue culture are much too slow to assist clinical decisions, taking weeks for completion. Genotypic assays may be performed directly on clinical samples such as blood, and cerebrospinal fluid and can be done by sequencing in a very few days.Finally, assays of lymphocytic functional responsiveness to cytomegalovirus can be used to identify transplant recipients at continuing risk for cytomegalovirus disease.

SUMMARY

Assays for CMV DNA or antigen in blood are superior to culture for documenting viremia and pneumonia. Genotypic assays have largely replaced phenotypic assays for CMV resistance to antivirals. Lymphocyte responses to CMV antigen(s) may identify patients at risk for CMV disease.

Maternal administration of valaciclovir in symptomatic intrauterine cytomegalovirus infection

OBJECTIVES

To report early experience with treatment of intrauterine cytomegalovirus (CMV) infection using maternal oral administration of valaciclovir (VACV).

DESIGN

Observational study of fetuses infected with CMV with or without treatment with valaciclovir.

POPULATION

Pregnancies with confirmed fetal CMV infection were treated with oral VACV (8 g/day).

MAIN OUTCOME MEASURES

Fetal viral load and drug concentration were monitored in amniotic fluid and in fetal blood. Data on the course and outcome of a group of untreated symptomatic fetuses infected with CMV are also reported.

RESULTS

Therapeutic concentrations were achieved in maternal and fetal bloods. The viral load in the fetal blood (VLFB) decreased significantly after 1-12 weeks of treatment (Wilcoxon paired test P = 0.02). Twenty pregnancies including 21 fetuses were treated at 28 weeks (median, range: 22-34) for 7 weeks (median, range: 1-12). Ten infants were developing normally at between 1 and 5 years of age. Two infants (both aged 2 years) had severe isolated unilateral deafness. One neonate presented with microcephaly and severe deafness but was also diagnosed with incontinentia pigmenti. Six out of seven cases that eventually required termination of pregnancy (TOP) had evidence of in utero progression of the disease with worsening cerebral lesions. One fetus died in utero. The outcome of 14/24 (58.3%) untreated symptomatic infected fetuses was poor with either TOP, intrauterine fetal demise or severe congenital infection disease of the neonate; the remaining ten infants were healthy at follow up.

CONCLUSION

Maternal oral administration of VACV leads to therapeutic concentrations in the maternal and fetal compartments, with a decrease in VLFB. Our results suggest that in cases where TOP is declined, a randomised controlled trial to study this treatment option further is indicated.

Analytic Validation of a Quantitative Real-time PCR Assay to Measure CMV Viral Load in Whole Blood

Cytomegalovirus (CMV) is a significant cause of morbidity and mortality in immunocompromised patients. We compared the CMV pp65 antigenemia test with a less labor intensive quantitative polymerase chain reaction (PCR) assay in 109 whole blood samples predominantly from transplant patients and patients with AIDS. DNA was amplified on an Applied Biosystems 7900 instrument using a TaqMan probe targeting the CMV polymerase gene and the APOB human control gene. The DNA assay was linear over a 6-log range from 8 to 800,000 CMV genomes per reaction; coefficient of variation was 20%. CMV DNA was undetectable in 20 blood samples from healthy donors whereas it was detected in 55 of 109 patient samples. Results were concordant in a nonlinear fashion with those of the antigenemia test in 90/109 (83%). Evaluation of the discrepancies suggested that either PCR or antigenemia assays could be falsely negative when virus levels were quite low. A point mutation interfered with probe binding in 1 sample. A second real-time PCR targeting the immediate early gene was even more likely to be false negative. In summary, CMV viral load measurement targeting the polymerase gene is nearly equivalent to the antigenemia assay for detecting and monitoring active CMV infection in whole blood samples.

Detection and monitoring of cytomegalovirus infection in renal transplant patients by quantitative real-time PCR

OBJECTIVES

To establish a sensitive and specific real-time PCR for quantitation of cytomegalovirus (CMV) DNA in clinical specimens.

SUBJECTS AND METHODS

In a prospective study, CMV DNA was quantified in blood samples of 255 kidney recipients with and without CMV-related symptoms between the years 2000 and 2005 in Kuwait. In a selected group of patients, the effect of anti-CMV chemotherapy was monitored by quantitative real-time PCR (qRT-PCR).

RESULTS

The established qRT-PCR assay had a sensitivity to detect 30 CMV DNA copies. CMV DNA was detected in 54/255 (24%) patients; of these, 17 (31.5%) were asymptomatic, and 37 patients (68.5%) had symptomatic CMV infection. Sequential blood specimens were collected from all CMV-positive patients and tested by CMV pp65 antigenemia and qRT-PCR assays. There was a moderate positive correlation between the two assays (Pearson's correlation = 0.52). The median CMV viral load measured by qRT-PCR was higher in symptomatic (6.5 x 10(4) copies/ml) than in asymptomatic (185copies/ml) patients (p = 0.001). The estimated cut-off value of CMV DNA for CMV symptoms/disease was > or =800 copies/ml of blood. Testing of sequential samples from patients treated with symptomatic CMV infection showed that the viral load was significantly reduced after 3 weeks of anti-CMV chemotherapy (p = 0.001).

CONCLUSION

The reported qRT-PCR is a sensitive method for quantitation of CMV DNA in the blood of kidney recipients and can be useful in monitoring the efficacy of anti-CMV therapy.

Fatal cytomegalovirus necrotising enteritis in a small bowel transplantation adult recipient with low pp65 antigenaemia levels

Although advances in immunosuppressive therapy have led to increased survival of solid organ transplantation recipients, it is well established that current protocols have been associated with an increased risk of developing tissue-invasive infections. In particular, cytomegalovirus still represents an important cause of morbidity. We report a case of cytomegalovirus infection involving the graft ileum with documented necrotising enteritis that developed after small bowel transplantation. The patient, a 56-year-old Caucasian female with a postsurgery short bowel syndrome, underwent a small bowel transplantation. Immunosuppression was maintained by combination of tacrolimus, steroids and daclizumab. Both the donor and the recipient were serologically negative for cytomegalovirus IgG. Nevertheless, ganciclovir prophylaxis was given for 21 days after surgery, as standard procedure. On hospital day 174, routine pp65 antigenaemia resulted positive (14/200,000 peripheral blood leukocytes). The patient was asymptomatic and preemptive ganciclovir therapy was instituted. In the following 3 days, due to a cytomegalovirus antigenaemia increase, ganciclovir was changed to foscarnet with subsequent virological response (7/200,000 peripheral blood leukocytes, on day 181). Two days later, the patient complained of acute abdominal pain and she underwent surgery for the diagnosis. Since the intraoperative findings consisted of a diffuse acute purulent peritonitis, the intestinal graft, together with native rectum, was removed. Biopsy specimens showed evidence of tissue-invasive cytomegalovirus infection. Postsurgery, the patient developed septic shock and died on day 198 as a consequence of multiple organ failure.