Quantitation of cytomegalovirus DNA by the polymerase chain reaction as a predictor of disease in solid organ transplantation

Molecular diagnosis of Cytomegalovirus infection: clinical performance of the Aptima transcription-mediated amplification assay toward conventional qPCR chemistry on whole blood samples

Human Cytomegalovirus (HCMV) infection is life-threatening for immunocompromised patients. Quantitative molecular assays on whole blood or plasma are the gold standard for the diagnosis of invasive HCMV infection and for monitoring antiviral treatment in individuals at risk of HCMV disease. For these reasons, an accurate standardization toward the WHO 1st International Standard among different centers and diagnostic kits represents an effort for better clinical management of HCMV-positive patients. Herein, we evaluate, for the first time, the performance of a new transcription-mediated amplification (TMA) assay versus quantitative polymerase chain reaction (qPCR) chemistry, used as a routine method, on whole blood samples. A total of 755 clinical whole blood specimens were collected and tested simultaneously with TMA and qPCR assays. The data showed a qualitative agreement of 99.27% for positive quantified samples and 89.39% for those undetected between the two tested methods. Evaluation of viremia in positive samples highlighted a good correlation between TMA and qPCR chemistries in terms of International Units (ΔLog10 IU/mL: -0.29 ± 0.40). The TMA assay showed a significant correlation with qPCR in patients monitored for up to 3 months, thus allowing an accurate assessment of viremia in transplant patients. Therefore, TMA chemistry showed good agreement with qPCR testing, used as a current diagnostic routine. It also offers important advantages, such as FDA approval on plasma and In Vitro Diagnostic (IVD) on both plasma and whole blood, automated workflow with minimal hands-on time, and random access loading, thus enabling a rapid and reliable diagnostic in HCMV-infected patients.

IMPORTANCE

In this paper, we describe the clinical performance of a novel transcription-mediated amplification (TMA) assay for the detection and quantification of human Cytomegalovirus (HCMV) DNA from whole blood samples. This is a pivotal analysis in immunocompromised patients [transplanted, HIV-positive, and Hematopoietic Stem Cell (HSC) recipients], and molecular tests with high sensitivity and specificity are necessary to evaluate the HCMV viral load in these patients. To our knowledge, this is the first in-depth evaluation of TMA chemistry for HCMV diagnosis on whole blood samples. Moreover, also technical aspects of this assay make it suitable for clinical diagnostics.

Evaluation of an electronic, patient-focused management system aimed at preventing cytomegalovirus disease following solid organ transplantation

BACKGROUND

Cytomegalovirus (CMV) infection is common among solid organ transplant (SOT) recipients and may cause CMV disease. To optimize the implementation of existing prevention strategies, the Management of Post-transplant Infections in Collaborating Hospitals (MATCH) program was developed. Two key performances of MATCH (diagnosing CMV infection at low viral load (VL) and before the onset of CMV disease) were assessed prior to, during and after the implementation of MATCH.

METHODS

The MATCH program included a personalized surveillance plan, prophylaxis and preemptive therapy determined by the recipient's risk of CMV infection. The plan was composed through predefined algorithms and implemented through harvesting of real-time data from medical records. Risk of CMV disease was compared for recipients transplanted during and after vs prior to the implementation of MATCH. Lung and non-lung transplants were analyzed separately.

RESULTS

A total of 593, 349, 520, and 360 SOT recipients were transplanted before (2007-2010), during (2011-2012), early after (2013-2015), and late after (2016-2017) implementation of MATCH with an observed reduction of diagnostic VL (P < .001) over time. Risk of CMV disease was reduced among non-lung transplant recipients transplanted during (adjusted hazard ratios [95% CI] 0.15 [0.04-0.54], P = .003), early after (aHR 0.27 [0.11-0.63], P = .003), and late after (aHR 0.17 [0.06-0.52], P = .002) compared with prior to MATCH. No significant change was observed among lung transplants.

CONCLUSION

Implementation of CMV preventive strategies through MATCH was associated with a reduced risk of CMV disease among non-lung transplant recipients. Furthermore, the limitations of VL as a sole indicator for CMV disease in lung transplants were emphasized.

Cytomegalovirus Viral Load in Bronchoalveolar Lavage to Diagnose Lung Transplant Associated CMV Pneumonia

BACKGROUND

The diagnostic yield for cytomegalovirus (CMV) polymerase chain reaction (PCR) viral load in bronchoalveolar lavage (BAL) or in plasma to diagnose CMV pneumonia in lung transplant recipients remains uncertain and was investigated in a large cohort of consecutive lung transplant recipients.

METHODS

Bronchoscopies within the first year of lung transplantation with CMV detectable in BAL by PCR (ie, viral load, ≥273 IU/mL) were included (66 recipients; 145 bronchoscopies); at each bronchoscopy episode, 2 independent experts reviewed clinical and laboratory information to determine whether the patient at that time fulfilled the criteria for CMV pneumonia per current international recommendations. Corresponding plasma CMV PCR viral load determined at time of the bronchoscopy (n = 126) was also studied. Optimal CMV PCR viral load cutoff for CMV pneumonia diagnosis was determined using receiver operating characteristics.

RESULTS

CMV was detected in BAL with CMV PCR in 145 episodes, and 34 (23%) of these episodes fulfilled the criteria for CMV pneumonia. The area under the curve-receiver operating characteristics for CMV in BAL was 90% at the optimum cutoff (4545 IU/mL) with a corresponding sensitivity of 91% and specificity of 77% (in plasma the corresponding values were 274 IU/mL, 63% and 76%, respectively).

CONCLUSIONS

CMV PCR viral load in BAL had a high performance to diagnose CMV pneumonia in lung transplant recipients; plasma CMV viral load did not reliably aid as a diagnostic tool.

Cytomegalovirus (CMV) Disease Despite Weekly Preemptive CMV Strategy for Recipients of Solid Organ and Hematopoietic Stem Cell Transplantation

Background

Transplant recipients presenting with cytomegalovirus (CMV) disease at the time of diagnosis of CMV DNAemia pose a challenge to a preemptive CMV management strategy. However, the rate and risk factors of such failure remain uncertain.

Methods

Solid organ transplantation (SOT) and hematopoietic stem cell transplantation (HSCT) recipients with a first episode of CMV polymerase chain reaction (PCR) DNAemia within the first year posttransplantation were evaluated (n = 335). Patient records were reviewed for presence of CMV disease at the time of CMV DNAemia diagnosis. The distribution and prevalence of CMV disease were estimated, and the odds ratio (OR) of CMV disease was modeled using logistic regression.

Results

The prevalence of CMV disease increased for both SOT and HSCT with increasing diagnostic CMV PCR load and with screening intervals >14 days. The only independent risk factor in multivariate analysis was increasing CMV DNAemia load of the diagnostic CMV PCR (OR = 6.16; 95% confidence interval, 2.09–18.11). Among recipients receiving weekly screening (n = 147), 16 (10.8%) had CMV disease at the time of diagnosis of CMV DNAemia (median DNAemia load 628 IU/mL; interquartile range, 432–1274); 93.8% of these cases were HSCT and lung transplant recipients.

Conclusions

Despite application of weekly screening intervals, HSCT and lung transplant recipients in particular presented with CMV disease at the time of diagnosis of CMV DNAemia. Additional research to improve the management of patients at risk of presenting with CMV disease at low levels of CMV DNAemia and despite weekly screening is warranted.

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

Background

Methods

Results

Conclusion

Clinical Application of Variation in Replication Kinetics During Episodes of Post-transplant Cytomegalovirus Infections

Background

Cytomegalovirus (CMV) infection in transplant recipients is reported to replicate with a doubling time of 1.2–2 days, and weekly screening is recommended for early diagnosis. We re-evaluated these features in our cohort of transplant recipients.

Methods

The CMV doubling time of the first CMV infection in the first year post-transplant could be calculated for 193 recipients of haematopoietic stem cell or solid organ transplantation. Factors determining the proportion of recipients with a high diagnostic CMV viral load (≥ 18,200 IU/mL) were explored using mathematical simulation.

Findings

The overall median doubling time was 4.3 days (IQR 2.5–7.8) and was not influenced by prior CMV immunity, or type of transplantation (p > 0.4). Assuming a fixed doubling time of 1.3 days and screening intervals of 7 or 10 days, 11.1% and 33.3% were projected to have a high CMV viral load at diagnosis, compared to 1.4% and 4.3% if the doubling time varies as observed in our cohort. Consistently, 1.9% of recipients screened weekly had a high diagnostic virus load.

Interpretation

Screening intervals can be extended to 10 days in cohorts with comparable CMV doubling time, whereas shorter than 7 days is required in cohorts with shorter doubling times to maintain pre-emptive screening quality.

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CMV doubling time was longer than previously reported, and not influenced by type of transplantation or prior CMV immunity.

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In cohorts with comparable CMV doubling time, intervals between screening with CMV PCR may be extended from 7 to 10 days.

Prevalence of human cytomegalovirus co-infection in patients with chronic viral hepatitis B and C: a comparison of clinical and histological aspects

BACKGROUND

Human cytomegalovirus (HCMV) is a common pathogen of severe disease in patients with impaired immune functions. Reactivation of HCMV in immunocompetent host is usually asymptomatic, but may deteriorate the prognosis of patient with chronic illness.

OBJECTIVES

This study was conducted to detect HCMV infection in patients with chronic hepatitis B virus (HBV) and chronic hepatitis C virus (HCV) infections and to point out the effects of HCMV-HBV and HCMV-HCV co-infections on liver histology.

STUDY DESIGN

Expression of HCMV DNA was determined in liver tissue biopsies by real-time quantitative polymerase chain reaction (qPCR) method. There were 44 chronic HBV, and 25 chronic HCV patients within the study group. Control group consisted of 36 patients with hepatologic malignancies.

RESULTS

HCMV infection was demonstrated in 52.3% of chronic HBV, and 36% of chronic HCV patients. Although alanine aminotransferase (ALT) levels of HCMV-infected HBV patients were decreased slightly, they were increased in HCV patients. Histologic activity scores (necroinflammation and fibrosis) of HCMV-positive patients were higher than that of HCMV-negatives in both HBV and HCV groups. Intrahepatic HBV DNA or HCV RNA loads of the corresponding study groups were decreased in HCMV-infected patients.

CONCLUSION

We conclude that HCMV infection is common in chronic HBV and HCV patients, who can be regarded as patients at high risk for HCMV disease. Though the histological changes were more marked in liver, replication of HBV and HCV were inhibited in HCMV-positive cases.

Diagnosing norovirus-associated infectious intestinal disease using viral load

Background

Reverse transcription-polymerase chain reaction (RT-PCR) is the main method for laboratory diagnosis of norovirus-associated infectious intestinal disease (IID). However, up to 16% of healthy individuals in the community, with no recent history of IID, may be RT-PCR positive; so it is unclear whether norovirus is actually the cause of illness in an IID case when they are RT-PCR positive. It is important to identify the pathogen causing illness in sporadic IID cases, for clinical management and for community based incidence studies. The aim of this study was to investigate how faecal viral load can be used to determine when norovirus is the most likely cause of illness in an IID case.

Methods

Real-time RT-PCR was used to determine the viral load in faecal specimens collected from 589 IID cases and 159 healthy controls, who were infected with genogroup II noroviruses. Cycle threshold (Ct) values from the real-time RT-PCR were used as a proxy measure of viral load. Receiver-operating characteristic (ROC) analysis was used to identify a cut-off in viral load for attributing illness to norovirus in IID cases.

Results

One hundred and sixty-nine IID cases and 159 controls met the inclusion criteria for the ROC analysis. The optimal Ct value cut-off for attributing IID to norovirus was 31. The same cut-off was selected when using healthy controls, or IID cases who were positive by culture for bacterial pathogens, as the reference negative group. This alternative reference negative group can be identified amongst specimens routinely received in clinical virology laboratories.

Conclusion

We demonstrated that ROC analysis can be used to select a cut-off for a norovirus real time RT-PCR assay, to aid clinical interpretation and diagnose when norovirus is the cause of IID. Specimens routinely received for diagnosis in clinical virology laboratories can be used to select an appropriate cut-off. Individual laboratories can use this method to define in-house cut-offs for their assays, to provide the best possible diagnostic service to clinicians and public health workers. Other clinical and epidemiological information should also be considered for patients with Ct values close to the cut-off, for the most accurate diagnosis of IID aetiology.

Valganciclovir as pre-emptive therapy for cytomegalovirus infection post-allogenic stem cell transplantation: implications for the emergence of drug-resistant cytomegalovirus

OBJECTIVES

Valganciclovir is a well established drug for the management of cytomegalovirus (CMV) infection in haematopoietic stem cell transplantation (HSCT). Data concerning its safety regarding the development of drug resistance are required. The aim of the present study was to retrospectively investigate CMV drug resistance in a group of HSCT patients experiencing relapses of CMV infection after a first-line pre-emptive antiviral therapy.

METHODS

Thirteen adult HSCT patients out of 26 with asymptomatic CMV infection, experiencing relapsing infections 45-155 days after either intravenous (iv) ganciclovir (2 patients) or valganciclovir (11 patients), were studied. Genotypic assays for mutations in the viral phosphotransferase (UL97) and DNA-polymerase (UL54) genes were directly applied on patient specimens. Baseline CMV sequences were compared with those at the time of relapses to identify drug-resistant strains.

RESULTS

UL97 mutations A594V and M460V known to confer drug resistance developed in one relapsing patient who received iv ganciclovir as first-line therapy, corresponding to a rate of 7.7% of relapses due to drug-resistant strains and an overall 3.8% rate of infections due to CMV drug-resistant strains. UL54 drug resistance mutations were absent. No evidence of drug resistance was found in patients on valganciclovir either as first-line therapy or as treatment for relapses.

CONCLUSIONS

The safety profile of valganciclovir as anti-CMV pre-emptive therapy was confirmed, as well as that monitoring CMV drug resistance with genotypic tests on sequential isolates over the time-course of therapy offers guidance to tailor antiviral treatment in a clinically relevant time frame.

Cytomegalovirus viremia in solid organ transplantation: does the initial viral load correlate with risk factors and outcomes?

Consistent data for using CMV quantitative PCR (QnPCR) on initial presentation to predict outcomes after solid organ transplantation (SOT) are lacking. Recipients with measurable CMV QnPCR and either CMV-V (asymptomatic viremia) or CMV-D (symptomatic CMV infection) were analyzed over 24 months. Risk factors and outcomes were evaluated in relation to initial QnPCR by regression analysis and time-to-event curves. Twenty-eight recipients were identified: five CMV-V, 23 CMV-D. Patients with CMV-D had a higher median initial QnPCR (230 000 copies/mL) compared with CMV-V (2500 copies/mL; p < 0.05). No patients with CMV-V had an initial QnPCR > 10 000 copies/mL compared with 83% of the CMV-D (p = 0.004). The initial QnPCR was higher (250 000 copies/mL) in patients who did not clear CMV PCR than those who cleared (8000 copies/mL) after 14 d of treatment (p = 0.03). Risk factors and indirect CMV effects were not associated with initial QnPCR. Our results highlight the importance of the initial CMV QnPCR in relation to the development of symptomatic CMV and a slower response to therapy. Alternatively, late asymptomatic viremia and recurrent CMV are associated with lower PCR levels and a low likelihood to progress and result in clinical disease.

Viral dynamics in transplant patients: implications for disease

Viral infections cause substantial morbidity and mortality in transplant patients. Quantifying viral loads is widely appreciated as a direct means to diagnose and monitor the course of viral infections. Recent studies indicate that the kinetics of viral load changes rather than single viral load measurements better correlate with organ involvement. In this Review, we will summarise the current knowledge regarding the kinetics of viruses relevant to transplantation including cytomegalovirus, Epstein-Barr virus, the herpes viruses 6 and 7, hepatitis C virus, GB virus C, adenovirus, and the emerging human polyomavirus type BK. We discuss the implications of viral kinetics for organ pathology as well as for the evaluation of antiviral interventions in transplant patients.

Quantitation of cytomegalovirus DNA by real-time polymerase chain reaction in peripheral blood specimens of patients with solid organ transplants: Comparison with end-point PCR and pp65 antigen test

The polymerase chain reaction (PCR) for cytomegalovirus (CMV) DNA quantitation provides sensitive and specific data for detecting CMV as well as monitoring the infection and determining the appropriate antiviral strategy. A recently introduced real-time PCR assay for CMV DNA quantitation was applied on 158 peripheral blood leukocytes (PBLs) from 32 liver-transplanted patients with CMV asymptomatic infection and correlated with a commercial quantitative end-point PCR (COBAS AMPLICOR CMV Monitor) and CMV pp65 antigenemia. A good correlation was found between real-time PCR and pp65 antigen test (r2 = 0.691) and the two PCR assays (r2 = 0.761). Real-time PCR data were higher in pre-emptive treated patients (>20 pp65 + positive cells, median CMV DNA value: 3.8 log(10) copies/500,000 PBLs) than in not-treated ones (2.9 logs). According to pp65 levels of 0, 1-10, 11-20, 21-50, 51-100, and >100 positive cells/200,000 PBLs, median CMV DNA by real-time PCR was 2.6, 3.0, 3.6, 4.0, 4.2, and 4.8 logs, respectively, (CMV DNA levels by COBAS AMPLICOR: 2.8, 2.9, 3.8, 3.7, 3.9, and 4.0 logs). For samples with >20 pp65 + cells, real-time PCR gave significantly higher values than in groups with <20 pp65 + cells, whereas the COBAS AMPLICOR results showed a slower progression rate. Dilutions of CMV AD169 strain were used to probe real-time PCR reproducibility (between and intra-assay variability <2%) and sensitivity (100% detection rate at 10 copies/reaction, 28.5% with end-point PCR). In conclusion, real-time PCR significantly improves the study of CMV DNA dynamics due to a more reliable quantitation of CMV DNA for moderate and high DNA level compared to end-point PCR with better sensitivity and specificity. Real-time PCR provides more precise information for evaluating infection progress and assessing antiviral response, simplifying and accelerating the process of producing a reliable quantitation of CMV DNA for clinical purposes.