Comparison of quantitative and qualitative PCR assays for cytomegalovirus DNA in plasma

Comparative analyses of DNA extraction methods for whole blood quantification of HCMV DNAemia in patients with hematological diseases: false negative cases in manual method

Human cytomegalovirus (HCMV) DNA quantitation in whole blood (WB) by real-time or quantitative polymerase chain reaction (qPCR) is a highly sensitive and reproducible diagnostic procedure for monitoring HCMV DNAemia (DNAemia is the detection of DNA in samples of plasma, whole blood, isolated peripheral blood leukocytes or in buffy-coat specimens) in patients. We provided a comparative analysis of HCMV DNA extraction performance by two different techniques, one performed by an automated extractor and the other by a manual method. We observed that the automated extraction method allowed HCMV DNA detection in the presence of weak viremia while no differences are observed when the viral load is greater. Therefore, automated DNA extraction is a suitable and recommended protocol not only for early detection of HCMV infection but also for more accurate monitoring of HCMV DNAemia during post-therapy follow-up.

Maternal and fetal outcomes of pregnant women with bacterial vaginosis

Background

Bacterial vaginosis (BV) is a common infection in women of reproductive age group because of vaginal dysbiosis. The impact of BV during pregnancy is still not well defined. The objective of this study is to assess the maternal-fetal outcome in women with BV.

Materials and Methods

A prospective cohort study over one-year duration was conducted from December, 2014 until December, 2015, involving 237 women who presented with abnormal vaginal discharge, preterm labour or preterm prelabour rupture of membrane between 22- and 34-weeks period of gestation. Vaginal swabs were sent for culture and sensitivity, BV® Blue testing and PCR for Gardnerella vaginalis (GV).

Results

BV was diagnosed in 24/237 (10.1%) cases. The median gestational age was 31.6 weeks. GV was isolated from 16 out of 24 (66.7%) in the BV positive group. There was a significantly higher preterm birth rate, below 34 weeks (22.7% vs. 6.2%, p = 0.019) in women with BV. There was no statistically significant difference in maternal outcome such as clinical chorioamnionitis or endometritis. However, placental pathology revealed more than half (55.6%) of women with BV had histologic chorioamnionitis. Neonatal morbidity was significantly higher with exposure to BV, with a lower median birth weight, higher rate of neonatal intensive care unit admission (41.7% vs. 19.0%, p = 0.010), increased intubation for respiratory support (29.2% vs. 7.6%, p = 0.004) and respiratory distress syndrome (33.3% vs. 9.0%, p = 0.002).

Conclusion

More research is needed to formulate guidelines for prevention, early detection and treatment of BV during pregnancy to reduce intrauterine inflammation and the associated adverse fetal outcomes.

Prevention and Management of CMV Infections after Liver Transplantation: Current Practice in German Transplant Centers

Human cytomegalovirus (CMV) remains a major cause of mortality and morbidity in human liver transplant recipients. Anti-CMV therapeutics can be used to prevent or treat CMV in liver transplant recipients, but their toxicity needs to be balanced against the benefits. The choice of prevention strategy (prophylaxis or preemptive treatment) depends on the donor/recipient sero-status but may vary between institutions. We conducted a series of consultations and roundtable discussions with German liver transplant center representatives. Based on 20 out of 22 centers, we herein summarize the current approaches to CMV prevention and treatment in the context of liver transplantation in Germany. In 90% of centers, transient prophylaxis with ganciclovir or valganciclovir was standard of care in high-risk (donor CMV positive, recipient CMV naive) settings, while preemptive therapy (based on CMV viremia detected during (bi) weekly PCR testing for circulating CMV-DNA) was preferred in moderate- and low-risk settings. Duration of prophylaxis or intense surveillance was 3-6 months. In the case of CMV infection, immunosuppression was adapted. In most centers, antiviral treatment was initiated based on PCR results (median threshold value of 1000 copies/mL) with or without symptoms. Therefore, German transplant centers report similar approaches to the prevention and management of CMV infection in liver transplantation.

Implementation and Validation of the Roche Light Cycler 480 96-Well Plate Platform as a Real-Time PCR Assay for the Quantitative Detection of Cytomegalovirus (CMV) in Clinical Specimens Using the Luminex MultiCode ASRs System

Allogenic stem-cell therapies benefit patients in the treatment of multiple diseases; however, the side effects of stem-cell therapies (SCT) derived from the concomitant use of immune suppression agents often include triggering infection diseases. Thus, analysis is required to improve the detection of pathogen infections in SCT. We develop a polymerase chain reaction (PCR)-based methodology for the qualitative real-time DNA detection of cytomegalovirus (CMV), with reference to herpes simplex virus types 1 (HSVI), Epstein–Barr virus (EBV), and varicella-zoster virus (VZV) in blood, urine, solid tissues, and cerebrospinal fluid. This real-time PCR of 96-well plate format provides a rapid framework as required by the Food and Drug Administration (FDA) for clinical settings, including the processing of specimens, reagent handling, special safety precautions, quality control criteria and analytical accuracy, precisely reportable range (analyst measurement range), reference range, limit of detection (LOD), analytical specificity established by interference study, and analyte stability. Specifically, we determined the reportable range (analyst measurement range) with the following criteria: CMV copies ≥200 copies/mL; report copy/mL value; CMV copies ≤199 copies/mL; report detected but below quantitative range; CMV copies = 0 with report <200 copies/mL. That is, with reference range, copy numbers (CN) per milliliter (mL) of the LOD were determined by standard curves that correlated Ct value and calibrated standard DNA panels. The three repeats determined that the measuring range was 1E2~1E6 copies/mL. The standard curves show the slopes were within the range −2.99 to −3.65 with R² ≥ 0.98. High copy (HC) controls were within 0.17–0.18 log differences of DNA copy numbers; (2) low copy (LC) controls were within 0.17–0.18 log differences; (3) LOD was within 0.14–0.15 log differences. As such, we set up a fast, simple, inexpensive, sensitive, and reliable molecular approach for the qualitative detection of CMV pathogens. Conclusion: This real-time PCR of the 96-well plate format provides a rapid framework as required by the FDA for clinical settings.

The Third International Consensus Guidelines on the Management of Cytomegalovirus in Solid-organ Transplantation

Despite recent advances, cytomegalovirus (CMV) infections remain one of the most common complications affecting solid organ transplant recipients, conveying higher risks of complications, graft loss, morbidity, and mortality. Research in the field and development of prior consensus guidelines supported by The Transplantation Society has allowed a more standardized approach to CMV management. An international multidisciplinary panel of experts was convened to expand and revise evidence and expert opinion-based consensus guidelines on CMV management including prevention, treatment, diagnostics, immunology, drug resistance, and pediatric issues. Highlights include advances in molecular and immunologic diagnostics, improved understanding of diagnostic thresholds, optimized methods of prevention, advances in the use of novel antiviral therapies and certain immunosuppressive agents, and more savvy approaches to treatment resistant/refractory disease. The following report summarizes the updated recommendations.

In vitro evaluation of current and novel antivirals in combination against human cytomegalovirus

Human cytomegalovirus (HCMV) can cause severe disease in patients with compromised or immature immune systems. Currently approved pharmacotherapies for the treatment of systemic HCMV infections [ganciclovir (GCV), cidofovir (CDV), foscarnet] are limited by a high incidence of adverse effects and/or the development of drug resistance. Given that many of these drugs have the same viral target (HCMV-encoded DNA polymerase), cross-resistance is relatively common. The primary means to combat drug resistance is combination pharmacotherapy using therapeutics with different molecular mechanisms of action with the expectation that those combinations result in an additive or synergistic enhancement of effect; combinations that result in antagonism can, in many cases, be detrimental to the outcome of the patient. We therefore tested select combinations of approved (GCV, CDV, letermovir (LMV)) and experimental (brincidofovir (BCV), cyclopropavir (CPV), maribavir (MBV), BDCRB) drugs with the hypothesis that combinations of drugs with different and distinct molecular mechanisms of action will produce an additive and/or synergistic enhancement of antiviral effect against HCMV in vitro. Using MacSynergy II (a statistical package that measures enhancement or lessening of effect relative to zero/additive), select drug combination studies demonstrated combination indices ranging from 160 to 372 with 95% confidence intervals greater than zero indicating that these combinations elicit a synergistic enhancement of effect against HCMV in vitro. These data suggest that administration of a viral DNA polymerase inhibitor, MBV, and/or a viral terminase inhibitor in combination has the potential to address the resistance/cross-resistance problems associated with currently available therapeutics.

Performance of an in-house real-time PCR assay for detecting Cytomegalovirus infection among transplant patients from a tertiary care centre

Background

Quantitative Cytomegalovirus (CMV) polymerase chain reactions are increasingly being used for monitoring CMV DNAemia in haematopoietic stem cell transplants and solid organ transplants.

Objective

In this study, a commercial CMV viral load assay was compared with an in-house viral load assay.

Materials and Methods

A total of 176 whole-blood samples were tested for CMV DNAemia using both assays.

Results

Our evaluation showed a difference of 1 log₁₀copies/ml between the two assay systems in determining CMV viral loads in the clinical samples.

Conclusion

The in-house viral load assay had a better correlation with clinical findings compared to the commercial assay. Quality assessment of these assays was done by the United Kingdom National External Quality Assessment Scheme (UKNEQAS), an external proficiency testing programme, and by the National Institute for Biological Standard and Control (NIBSC) standard. For UKNEQAS and NIBSC standards, the bias between the assays was 0.73 log₁₀and 0.85 log₁₀, respectively. This difference is well within the acceptable range already reported in the literature.

Human Cytomegalovirus Infection in Nonimmunocompromised Patients: A Retrospective Analysis and Review of the Literature

In a retrospective analysis of patients visiting the Outpatient Department of the Division of Infectious Diseases and Tropical Medicine over a period of 3 years, we found a high incidence of symptomatic nonsevere human cytomegalovirus (HCMV) infection in nonimmunocompromised patients. We present 11 symptomatic cases of HCMV infection in nonimmunocompromised patients with non-life-threatening symptoms like long-lasting depletion, fatigue, and subfebrile fever with or without muscular pain and arthralgia. Although the symptoms were not life-threatening, all of the patients suffered a prolonged duration of the disease until improvement. These cases reinforce the important fact that HCMV infections in nonimmunocompromised patients are not always asymptomatic. Therefore, HCMV infection should always be included in the differential diagnosis of patients with unspecific signs of disease like depletion, subfebrile fever, and arthralgia.

Cytomegalovirus Colitis and Subsequent New Diagnosis of Inflammatory Bowel Disease in an Immunocompetent Host: A Case Study and Literature Review

Patient: Male, 40

Final Diagnosis: CMV colitis

Symptoms: Abdominal pain • diarrhea • jaundice

Medication: —

Clinical Procedure: Flexible sigmoidoscopy • colonoscopy

Specialty: Family Medicine

How to develop an in-house real-time quantitative cytomegalovirus polymerase chain reaction: Insights from a cancer centre in Eastern India

Development of a reliable, cost-effective cytomegalovirus quantitative polymerase chain reaction (QPCR) is a priority for developing countries. Manufactured kits are expensive, and availability can be inconsistent. Development of an in-house QPCR kit that is reliable and quality assured requires significant effort and initial investment. However, the rewards of such an enterprise are manifold and include an in-depth understanding of molecular reactions, and expertise in the development of further low-cost molecular kits. The experience of an oncology centre in Eastern India has been shared. Hopefully, this would provide a brief roadmap for such an initiative. Staff with adequate understanding of molecular processes are essential along with vital infrastructure for molecular research and development.

Cytomegalovirus quantification in plasma with Abbott RealTime CMV and Roche Cobas Amplicor CMV assays

We assessed the performance of Abbott RealTime CMV assay (ARC) compared to Roche Cobas Amplicor CMV Monitor Test (RCM) for quantification of CMV in plasma of transplant patients. Commercial panels were used to test linearity, precision and interference and 83 clinical samples were used for the accuracy and precision analyses. All 43 RCM-positive clinical samples tested positive by ARC. The overall concordance between the two tests was good (98%). Based on 17 samples, the inter-assay median coefficient of variation was 13%. A linearity panel ranging from approximately 1 to 7log10copies/mL was used to confirm linearity (R(2)=0.99). CMV viral load measurement was not affected by different concentrations of HSV-1 or EBV DNA. We conclude that The Abbott RealTime CMV assay offers good sensitivity, precision and linearity and is suitable for monitoring CMV viral loads in transplant recipients. Standardization with the WHO CMV standard allows for comparison with other assays.

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.

Quantitation of cytomegalovirus DNA load in dried blood spots correlates well with plasma viral load

An assay to accurately quantitate cytomegalovirus (CMV) load in finger-stick-collected dried blood spots (DBS) could potentially be useful for field studies or for analyzing patient self-collected specimens. We therefore assessed CMV DNA load in paired venipuncture-collected plasma samples and finger-stick DBS, using a previously validated quantitative PCR assay. Assay variability, sensitivity, and changes in viral load during antiviral therapy in finger-stick DBS were compared to the reference plasma quantitative PCR assay, using 106 prospectively collected pairs of finger-stick DBS and plasma samples from 35 solid-organ transplant (SOT) patients. The DBS assay showed good agreement with the reference plasma viral load assay on the log10 scale (Pearson correlation coefficient, 0.92; P < 0.001). The 95% limit of detection of the DBS assay was estimated at 2,700 plasma copies/ml (675 plasma IU/ml). In 94% (76/81) of paired DBS and plasma samples above the limit of detection, the difference in CMV load was <1 log10. CMV viral load changes during antiviral treatment were comparable in plasma and DBS. We conclude that finger-stick DBS provides a convenient sample type for quantitation of CMV load that correlates well with plasma levels. Future studies to optimize and evaluate this methodology for patient self-collected samples are warranted.

Development and evaluation of a loop-mediated isothermal amplification assay for the rapid detection of porcine cytomegalovirus under field conditions

Background

Porcine cytomegalovirus (PCMV) induces silent infection in adult pigs but more frequently causes fatal, generalized infection in newborn piglets. This study aimed to develop a new loop-mediated isothermal amplification (LAMP) method for the sensitive, rapid, and inexpensive detection of PCMV under field conditions.

Methods

Tissue obtained from nine-week-old PCMV-free Landrace pigs or pig samples from postmortem examinations were analyzed. The samples were found to have clinical signs and lesions consistent with inclusion body rhinitis. Six specific primers were designed by targeting the PCMV DNA polymerase (DPOL) DNA. The LAMP reaction was optimized in a water bath. The sensitivity and specificity of LAMP and polymerase chain reaction (PCR) were compared.

Results

PCMV DNA was amplified at 65°C, and the result could be detected as early as 30 min into the reaction. Positive reactions could be visualized by the naked eye as a color change brought on by the addition of SYBR Green. The sensitivity and specificity of LAMP were found to be similar to those of the PCR.

Conclusions

LAMP is a high-throughput technique for the detection of PCMV and has a high specificity, sensitivity and simplicity; these factors make it suitable for detection of PCMV under field conditions.

Cytomegalovirus infection and the gastrointestinal tract

Cytomegalovirus (CMV) infection is common worldwide, but the majority are asymptomatic. However, during initial infection or reactivation, CMV can cause tissue-invasive end-organ damage including in the gastrointestinal tract, especially in immunocompromised individuals. Gastrointestinal CMV disease can present with myriad of symptoms and be highly variable endoscopically. In this article we review the manifestations of CMV infection within the luminal gastrointestinal tract and discuss the options for diagnosis and management.

Kinetics of human cytomegalovirus (HCMV) DNAemia in transplanted patients expressed in international units as determined with the Abbott RealTime CMV assay and an in-house assay

BACKGROUND

Consensus human cytomegalovirus (HCMV) DNA cut-off values for preemptive therapy in transplant recipients have not yet been defined, mainly due to the lack of real-time PCR standardization.

OBJECTIVES

(i) To compare the kinetics of HCMV DNA in transplanted patients using an in-house real-time PCR assay (Pavia assay) and the new Abbott RealTime CMV assay; (ii) to verify assay concordance in the identification of patients eligible for preemptive treatment and (iii) standardize results with international units (IUs) using the WHO International HCMV DNA Standard as a reference.

STUDY DESIGN

The kinetics of HCMV disseminated infection was retrospectively evaluated in 513 stored whole blood samples from 37 transplanted patients enrolled in randomized prospective studies designed for the clinical validation of HCMV DNA cut-off values. Conversion factors of HCMV DNA copy number to WHO international units (IUs) were determined.

RESULTS

Among the 513 samples, 352 (68.6%) were concordant positive, 42 (8.1%) concordant negative and 119 (23.1%) discordant. All discordant samples resulted positive by the Abbott RealTime CMV assay and negative by the Pavia assay, showing higher sensitivity for the Abbott RealTime CMV assay. A significant correlation was observed between concordant positive samples (r=0.89). HCMV DNAemia determined by each assay showed overlapping kinetics. Expression of results as IU/ml provided the best results in preemptive treatment simulation.

CONCLUSION

HCMV DNAemia cut-off values determined using our in-house assay and expressed as IU/ml appear valid for use in commercial assays as well as other potential in-house assays.

Assessment of Aspergillus fumigatus in guinea pig bronchoalveolar lavages and pulmonary tissue by culture and realtime polymerase chain reaction studies

In this study we pursued a diagnostic target in Aspergillus fumigatus (AF) by using qualitative Realtime PCR combined with proprietary DNA primers and a hydrolysis probe specific for this fungal target. Qualitative Realtime PCR is a diagnostic tool that utilizes Realtime PCR technology and detects the presence or absence target specific DNA within a predetermined detection range. Respiratory tissue and fluids from experimentally infected guinea pigs were tested by extracting DNA from the samples which were amplified and detected using AF specific DNA primers and probe. This study included qualitative evaluations of all specimens for the presence of the DNA of AF. The findings in the tissues after AF infection were compared to the numbers of spores in aerosolized samples used to inoculate the animals. Results demonstrated that the specific probe and primer set could detect the presence or absence of AF DNA in the sample. The qualitative detection limit of the assay ranged from 6 × 10⁴ copies to 6 copies. Since blood cultures are rarely positive for Aspergillosis, our data indicate that qualitative Realtime PCR, in combination with the appropriate DNA primers and probe can serve as an effective diagnostic tool in the early detection of fungal infections.

Comparative evaluation of three automated systems for DNA extraction in conjunction with three commercially available real-time PCR assays for quantitation of plasma Cytomegalovirus DNAemia in allogeneic stem cell transplant recipients

Limited data are available on the performance of different automated extraction platforms and commercially available quantitative real-time PCR (QRT-PCR) methods for the quantitation of cytomegalovirus (CMV) DNA in plasma. We compared the performance characteristics of the Abbott mSample preparation system DNA kit on the m24 SP instrument (Abbott), the High Pure viral nucleic acid kit on the COBAS AmpliPrep system (Roche), and the EZ1 Virus 2.0 kit on the BioRobot EZ1 extraction platform (Qiagen) coupled with the Abbott CMV PCR kit, the LightCycler CMV Quant kit (Roche), and the Q-CMV complete kit (Nanogen), for both plasma specimens from allogeneic stem cell transplant (Allo-SCT) recipients (n = 42) and the OptiQuant CMV DNA panel (AcroMetrix). The EZ1 system displayed the highest extraction efficiency over a wide range of CMV plasma DNA loads, followed by the m24 and the AmpliPrep methods. The Nanogen PCR assay yielded higher mean CMV plasma DNA values than the Abbott and the Roche PCR assays, regardless of the platform used for DNA extraction. Overall, the effects of the extraction method and the QRT-PCR used on CMV plasma DNA load measurements were less pronounced for specimens with high CMV DNA content (>10,000 copies/ml). The performance characteristics of the extraction methods and QRT-PCR assays evaluated herein for clinical samples were extensible at cell-based standards from AcroMetrix. In conclusion, different automated systems are not equally efficient for CMV DNA extraction from plasma specimens, and the plasma CMV DNA loads measured by commercially available QRT-PCRs can differ significantly. The above findings should be taken into consideration for the establishment of cutoff values for the initiation or cessation of preemptive antiviral therapies and for the interpretation of data from clinical studies in the Allo-SCT setting.

Diagnostic value of antigenemia assay for cytomegalovirus gastrointestinal disease in immunocompromised patients

AIM: To investigate the utility of the cytomegalovirus (CMV) antigenemia assay for the diagnosis of CMV gastrointestinal disease (GID).

METHODS: One hundred and thirty immunocompromised patients were enrolled in this study. Patients with a history of anti-CMV treatment and who had not undergone examination using the antigenemia assay were excluded. CMV-GID was defined as the detection of large cells with intranuclear inclusions alone or associated with granular cytoplasmic inclusions by biopsy. Biopsy sections were stained with hematoxylin and eosin and immunohistochemically stained with anti-CMV. We evaluated the association between CMV-GID and patient characteristics (symptoms, underlying disease, medication, leukocyte counts, and antigenemia assay). All patients were checked with an human immunodeficiency virus (HIV) antibody test before endoscopic examination. White blood cell (WBC) counts were obtained from medical records within 1 wk of endoscopy. Leukopenia was defined as a total WBC count < 5000 cells/mm³. For HIV patients, we also checked CD4+ counts from medical records.

RESULTS: A total of 99 patients were retrospectively selected for analysis. Of the immunocompromised patients, 19 had malignant disease, 18 had autoimmune disease, 19 had disorders of biochemical homeostasis, three had undergone transplantation, and 45 had HIV infection. A total of 50 patients had received immunosuppressive therapy. No patients had inflammatory bowel disease. Fifty-five patients were diagnosed as having CMV-GID. Univariate analysis indicated an association between HIV infection, leukopenia, and positive antigenemia and CMV-GID (P < 0.05). Multivariate analysis using logistic regression revealed that HIV infection and positive antigenemia were the only independent factors related to CMV-GID (P < 0.01). The sensitivity, specificity, positive predictive value, and negative predictive value of antigenemia for CMV-GID were 65.4%, 93.6%, 91.9%, and 71.0%, respectively. In a subgroup analysis, patients with leukopenia displayed low sensitivity and high specificity. Minimal differences in accuracy were seen among patients with or without leukopenia. HIV-infected patients displayed low sensitivity and high specificity. Accuracy barely differed between HIV-positive and -negative patients. In HIV-infected patients, CD4 count < 50 cells/μL resulted in low sensitivity and high specificity. Differences in accuracy among patients were minor, regardless of CD4 count. In patients who had undergone both quantitative real-time polymerase chain reaction (PCR) and antigenemia assay, real-time PCR was slightly more accurate in terms of sensitivity than the antigenemia assay; however, this difference was not statistically significant (P = 0.312).

CONCLUSION: If the antigenemia test is positive, endoscopic lesions are acceptable for the diagnosis of CMV-GID without biopsy. The accuracy is not affected by HIV infection and leukopenia. Either PCR or the antigenemia assay are valid.

International consensus guidelines on the management of cytomegalovirus in solid organ transplantation

Cytomegalovirus (CMV) remains one of the most common infections after solid organ transplantation, resulting in significant morbidity, graft loss, and occasional mortality. Management of CMV varies considerably among transplant centers. A panel of experts on CMV and solid organ transplant was convened by The Infectious Diseases Section of The Transplantation Society to develop evidence and expert opinion-based consensus guidelines on CMV management including diagnostics, immunology, prevention, treatment, drug resistance, and pediatric issues.

Cytomegalovirus infection in children undergoing hematopoietic stem cell transplantation in Chile

BACKGROUND

Cytomegalovirus (CMV) infection remains as an important cause of morbidity and mortality in children undergoing hematopoietic stem cell transplantation (HSCT). Our aim was to assess the incidence, risk factors, and outcome related to CMV infection in children after HSCT in a developing country.

METHODS

From October 1, 1999, to December 31, 2005, we prospectively studied all patients admitted to the HSCT unit at Hospital Luis Calvo Mackenna in Santiago, Chile. Serologic studies before transplantation and weekly CMV infection surveillance (antigenemia or quantitative PCR) were routinely obtained. Patients with positive antigenemia or quantitative PCR received pre-emptive therapy with ganciclovir, and cases of unfavorable clinical evolution, persistent positive antigenemia, or quantitative PCR after 14 days of ganciclovir were treated with foscarnet.

RESULTS

Ninety-seven patients received HSCT. Their median age was 8 years (range, 3 months to 24 years) and their overall survival was 67%. CMV reactivation was diagnosed in 26 patients. Of these, three developed CMV disease (two interstitial pneumonia, one hemorrhagic cystitis). One of the patients with pneumonia died. Risk factors identified were pre-transplant serologic status (positive recipient), acute and chronic graft versus host disease (GvHD), GvHD prophylaxis, and treatment with antithymocyte globulin.

CONCLUSIONS

The rate and prognosis of CMV infection among children treated at our HSCT unit is similar to those reported from industrialized countries. These findings reflect adequate prevention and management of CMV infection within our program.

Evaluation of interleukin-6 and interleukin-10 in lung transplant patients with human cytomegalovirus infection

We hypothesized that interleukin-6 (IL-6) in plasma and bronchoalveolar lavage (BAL) might serve as additional diagnostic parameter in lung transplant patients with human cytomegalovirus (HCMV) infection. Therefore, we compared IL-6 levels in HCMV-positive vs. HCMV-negative patients. IL-6 was measured by ELISA in plasma and BAL in 111 patients. Furthermore, we investigated the influence of IL-10 on IL-6 production in HCMV-positive patients. For HCMV-DNA detection in plasma and BAL a quantitative polymerase chain reaction (PCR) assay was used. IL-6 levels were significantly higher in the HCMV-positive group (n = 39; BAL p = 0.045; plasma p = 0.017) in comparison to the HCMV-negative group (n = 72). IL-10 did not correlate with IL-6 concentration (p = 0.146). Donor (D) or recipient (R) HCMV-constellation did not influence IL-6 concentration. IL-6 levels were not influenced by elevated levels of HCMV copies. Our data suggest that IL-6 does not serve as a good diagnostic parameter for existence of HCMV infection in lung transplant patients. Because of the wide range of the IL-6 levels in both groups, we were not able to find a breakpoint differentiating between infected and not-infected patients. Another important finding was that IL-6 production is not dependent of the HCMV status of D/R.

Multi-Site PCR-based CMV viral load assessment-assays demonstrate linearity and precision, but lack numeric standardization: a report of the association for molecular pathology

Viralload (VL) assessment of cytomegalovirus (CMV) by real-time PCR is an important tool for diagnosing and monitoring CMV viremia in patients with compromised immune systems. We report results from a sample exchange organized by members of the Association for Molecular Pathology that compared PCR results from 23 laboratories; 22 such laboratories used a laboratory-developed real-time PCR assay and one laboratory used a competitive PCR assay. The samples sent to each laboratory were comprised of a dilution panel of CMV virion-derived reference materials that ranged from 0 to 500,000 copies/ml. Accuracy, linearity, and intralaboratory precision were established for the different laboratory-developed assays. Overall, PCR results were linear for each laboratory (R(2) > 0.97 in all but two). While 13 laboratories showed no significant quantitative assay bias, 10 laboratories reported VLs that were significantly different compared with expected values (bias range, -0.82 to 1.4 logs). The intralaboratory precision [mean coefficient of variance of 2% to 5% (log-scale)] suggested that changes in VLs of less than 3- to fivefold may not be significantly different. There was no significant association between laboratory-specific technical variables (PCR platform, calibrator, extraction method) and assay linearity or accuracy. These data suggested that, within each laboratory, relative VL values were linear, but additional method standardization and a CMV DNA reference standard are needed to allow laboratories to achieve comparable numeric results.

Manifestations of human cytomegalovirus infection: proposed mechanisms of acute and chronic disease

Infections with human cytomegalovirus (HCMV) are a major cause of morbidity and mortality in humans with acquired or developmental deficits in innate and adaptive immunity. In the normal immunocompetent host, symptoms rarely accompany acute infections, although prolonged virus shedding is frequent. Virus persistence is established in all infected individuals and appears to be maintained by both a chronic productive infections as well as latency with restricted viral gene expression. The contributions of the each of these mechanisms to the persistence of this virus in the individual is unknown but frequent virus shedding into the saliva and genitourinary tract likely accounts for the near universal incidence of infection in most populations in the world. The pathogenesis of disease associated with acute HCMV infection is most readily attributable to lytic virus replication and end organ damage either secondary to virus replication and cell death or from host immunological responses that target virus-infected cells. Antiviral agents limit the severity of disease associated with acute HCMV infections, suggesting a requirement for virus replication in clinical syndromes associated with acute infection. End organ disease secondary to unchecked virus replication can be observed in infants infected in utero, allograft recipients receiving potent immunosuppressive agents, and patients with HIV infections that exhibit a loss of adaptive immune function. In contrast, diseases associated with chronic or persistent infections appear in normal individuals and in the allografts of the transplant recipient. The manifestations of these infections appear related to chronic inflammation, but it is unclear if poorly controlled virus replication is necessary for the different phenotypic expressions of disease that are reported in these patients. Although the relationship between HCMV infection and chronic allograft rejection is well known, the mechanisms that account for the role of this virus in graft loss are not well understood. However, the capacity of this virus to persist in the midst of intense inflammation suggests that its persistence could serve as a trigger for the induction of host-vs-graft responses or alternatively host responses to HCMV could contribute to the inflammatory milieu characteristic of chronic allograft rejection.

Usefulness of Interleukin-10 Detection in Lung Transplant Patients With Human Cytomegalovirus Infection With Respect to Virus Persistence

BACKGROUND

Human cytomegalovirus (HCMV) infection in lung transplant patients induces an inflammatory response, including local production of cytokines involved in viral clearance. The aim of this study was to evaluate the potential value of monitoring interleukin (IL)-10 with respect to HCMV persistence in blood and/or bronchoalveolar lavage (BAL).

METHODS

A quantitative polymerase chain reaction assay was used for HCMV-DNA detection in plasma and BAL. IL-10 was measured with an enzyme-linked immunosorbent assay in blood and with BAL in 101 lung transplant patients. IL-10 levels were correlated with clinical outcome.

RESULTS

A total of 23 patients of 35 (66%) with detectable HCMV in plasma and/or BAL exhibited increased levels of IL-10 in plasma and/or BAL. Complete clearance of HCMV was observed after 168 (median 130) days in the IL-10-positive group (n=23) in comparison with 87 (median 58) days in the IL-10-negative group (n=12; P<0.024). In the seven HCMV-positive patients with positive IL-10 levels in BAL only, HCMV persisted in BAL for a median of 579 days without signs of systemic infection (positive plasma levels) or clinical symptoms.

CONCLUSIONS

We show that in lung transplant patients with elevated levels of IL-10 in plasma and/or BAL, HCMV clearance is prolonged because of the influence of anti-inflammatory cytokines.

CMV monitoring using blood cells and plasma: a comparison of apples with oranges?

Quantitative cytomegalovirus (CMV) monitoring is still far from being standardized between transplant centers. In the present study, we compared assays for quantitative CMV monitoring using blood cells and plasma. Four hundred and thirty-five consecutive samples from 29 patients with active CMV infection after allogeneic T-cell-depleted hemopoietic stem cell transplantation were tested in parallel using pp65 antigenemia and quantitative CMV polymerase chain reaction (PCR) in blood cells and plasma (COBAS AMPLICOR CMV MONITOR). Although only 142 (53.1%) of 253 positive samples were concordantly identified by all three assays, the number of positive samples detected by each assay was not different and the quantitative values were correlated, provided that nucleic acid (NA) in plasma was isolated by COBAS AmpliPrep and not by the manual protocol. Six (18%) of 34 episodes with active CMV infection were not detected using CMV PCR in plasma; whereas in times of white blood cell aplasia or blast crisis of leukemia, samples with active CMV infection in plasma could not be detected using blood cells. We conclude that CMV monitoring in whole blood could be favorable compared with assays using plasma or blood cells alone. Automated NA isolation could become an attractive tool for a more sensitive and better standardized molecular diagnostics.

Role of cell culture for virus detection in the age of technology

Viral disease diagnosis has traditionally relied on the isolation of viral pathogens in cell cultures. Although this approach is often slow and requires considerable technical expertise, it has been regarded for decades as the "gold standard" for the laboratory diagnosis of viral disease. With the development of nonculture methods for the rapid detection of viral antigens and/or nucleic acids, the usefulness of viral culture has been questioned. This review describes advances in cell culture-based viral diagnostic products and techniques, including the use of newer cell culture formats, cryopreserved cell cultures, centrifugation-enhanced inoculation, precytopathogenic effect detection, cocultivated cell cultures, and transgenic cell lines. All of these contribute to more efficient and less technically demanding viral detection in cell culture. Although most laboratories combine various culture and nonculture approaches to optimize viral disease diagnosis, virus isolation in cell culture remains a useful approach, especially when a viable isolate is needed, if viable and nonviable virus must be differentiated, when infection is not characteristic of any single virus (i.e., when testing for only one virus is not sufficient), and when available culture-based methods can provide a result in a more timely fashion than molecular methods.

Detection of β-herpesviruses in allogenic stem cell recipients by quantitative real-time PCR

The aim of this study was to investigate the clinical impact of reactivation of human herpes virus-6 (HHV-6) and HHV-7 infections in stem cell transplantation recipients, and to examine a possible increase in virulence of the two roseoloviruses when a reactivation of CMV (HHV-5) simultaneously occurs. For this purpose, quantitative real-time PCR systems were developed to assess the viral load of CMV, HHV-6, or HHV-7 in the plasma of haematopoetic stem cell recipients. One hundred and ninety-eight plasma samples from 37 patients who underwent allogeneic stem cell transplantation were tested for CMV, HHV-6, and HHV-7 by a 5'-exonuclease (TaqMan) quantitative real-time PCR. The CMV load obtained by the real-time PCR assay was compared retrospectively with results generated previously with a commercially available test (COBAS AMPLICOR CMV MONITOR Test, Roche). The results suggest that CMV and HHV-6 may be associated with post-transplantation end-organ disease, while HHV-7 reactivation had no impact on the patients included in this study. No evidence for a potential interaction of the roseoloviruses and CMV infections was found.

Cytomegalovirus colitis complicating inflammatory bowel disease

When patients with inflammatory bowel disease (IBD) are admitted to the hospital with a flare of acute severe colitis, the possibility of a concurrent cytomegalovirus (CMV) infection causing or worsening the colitis is often considered. IBD patients are usually immunosuppressed, and therefore presumably at increased risk for active CMV infection and disease. Multiple techniques are used to diagnose CMV infection, including endoscopy, histology, serology, viral culture, CMV antigen testing, and CMV DNA testing. Immunohistochemistry (IHC) performed on colon biopsy specimens with monoclonal antibodies directed against CMV immediate early antigen is considered by most to be the current gold standard for diagnosis. The prevalence of CMV infection in acute severe colitis appears to be 21-34%, and the prevalence of CMV infection in the steroid refractory subgroup of these patients is 33-36%. After antiviral therapy, colitis remission rates in IBD patients with CMV infection range from 67% to 100%, though CMV histological infection or the presence of circulating virus alone is not always associated with steroid resistance, and may not require antiviral therapy.

Evaluation of the COBAS Amplicor HCMV Monitor for early detection and monitoring of human cytomegalovirus infection after allogeneic stem cell transplantation

Early diagnosis of human cytomegalovirus (HCMV) infection and the introduction of preemptive antiviral therapy have reduced HCMV-related mortality after allogeneic stem cell transplantation. A critical goal remains stratifying risk profiles and minimizing potential harm owing to antiviral overtreatment. We compared the commercially available standardized COBAS Amplicor CMV Monitor (CACM) to an in-house PCR assay, for the monitoring of HCMV infection. Seventy-two patients were surveyed by an in-house PCR of whole blood, quantitative viral load assessment by CACM and virus culture assays in a prospective and a retrospective study. A high concordance between CACM and PCR was documented. The viral load at onset correlated with the peak viral load (Spearman rank correlation R=0.634, P=0.0004). In patients developing HCMV disease, both viral loads were in trend higher (P=0.823, respectively P=0.053), and the viremic episodes longer (P=0.015), as compared to asymptomatically HCMV-infected patients. The serological pre-transplant status was the major risk factor for the development of HCMV disease, showing highest risk for seropositive patients receiving a seronegative graft, whereas donor type (related or unrelated) and graft type (bone marrow or peripheral blood mobilized stem cells) did not have an influence. HCMV infection proved to be a risk factor for the development of non-viral opportunistic infections (P=0.002).

American Society of Transplantation recommendations for screening, monitoring and reporting of infectious complications in immunosuppression trials in recipients of organ transplantation

In recent years, major progress has been made in the development, investigation and clinical application of novel immunosuppressive drug therapies to prevent acute rejection. Critical to the ultimate clinical application of new drug therapies is the ongoing performance of large multi-center clinical trials. However, there has been a paucity of infectious disease monitoring built into these protocols. Given that infectious complications are a major source of morbidity and mortality in transplant recipients, the assessment of the magnitude of risk of infection associated with a given immunosuppressive strategy may be as important as the assessment of rejection. For the above reasons, screening, monitoring and reporting recommendations for common transplant-associated infections were developed for use in clinical trials evaluating immunosuppressive strategies. These recommendations have two major goals: (i) to provide clinically relevant definitions for tracking infectious complications occurring in participants in immunosuppressive trials and (ii) where appropriate, to recommend specific laboratory monitoring and surveillance methods.

Cytomegalovirus Pneumonia in Transplant Recipients

The incidence of cytomegalovirus CMV pneumonia has been reduced by routine antiviral prophylaxis in susceptible populations. Many of the complications of this infection are caused by indirect effects of the virus, including acute and chronic graft rejection, graft-versus-host disease, and superinfection by other viruses, bacteria and fungi. Distinction must be made between viral secretion and invasion. Invasive procedures are often required for the optimal management of such infections. The use of sensitive and quantitative assays have greatly improved the outcomes of CMV infection.

Comparison of Cytomegalovirus Viral Load Measure by Real-Time PCR With pp65 Antigenemia for the Diagnosis of Cytomegalovirus Disease in Solid Organ Transplant Patients

Cytomegalovirus (CMV) infection is the most frequent complication in solid organ transplant recipients. Currently, the antigenemia assay is widely used to detect this infection, although its success is being questioned to a great extent nowadays. The aim of our study is to compare a quantitative real time PCR to measure CMV DNA to the antigenemia assay, for the diagnosis to CMV disease. For our research, we prospectively processed 1198 samples (plasma and peripheral blood leukocytes [PBMC]), which belonged to 158 transplant recipients. In every sample the detection of the pp65 antigen in PBMC was carried out, as well as the quantification of CMV DNA by PCR (Light Cycler, LC-PCR). For this process, FRET probes, which detect a 254-bp fragment from the CMV gB gene, were used. The dynamic range of the LC-PCR was 500 to 5.10(7) copies/mL plasma and from 62 to 6.10(6) copies/10(6) PBMC. Twenty-three episodes of cytomegalovirus (CMV) disease occurred in 22 out of 158 patients and PCR displayed levels of sensitivity and specificity of 100% and 67%, respectively. The antigenemia assay obtained values of 91% and 57%. We established a cutoff value of 10(3) copies/mL plasma and 315 copies/10(6) cells. According to these cutoff values, PCR showed levels of sensitivity, specificity, VPN and VPP of 95.6%, 81.6%, 99%, and 53% respectively. Moreover, the LC-PCR assay anticipated the antigenemia assay in 10 patients out of 22 who developed CMV disease and the appearance of any clinical symptoms in 12 out of 22 patients. In conclusion, we believe that the quantification of CMV DNA by LC-PCR is a superior assay to pp65 antigenemia test regarding the early diagnosis of CMV disease in solid organ transplant recipients.

Cytomegalovirus Viremia, Mortality, and End-Organ Disease Among Patients With AIDS Receiving Potent Antiretroviral Therapies

OBJECTIVE

To determine the association of cytomegalovirus (CMV) viremia with CMV disease and death in patients with AIDS.

DESIGN AND SETTING

Prospective, observational cohort study conducted at a university hospital.

METHODS

A cohort of 190 subjects with AIDS who were CMV seropositive and had no history or evidence of CMV disease were longitudinally evaluated for signs and symptoms of CMV disease and CMV viremia with plasma CMV DNA polymerase chain reaction (PCR) and whole blood CMV hybrid capture.

RESULTS

A total of 187 subjects had at least 1 study visit following entry. At baseline, the median CD4 cell count and plasma HIV RNA level were 110/microL (range = 3-620/microL) and 47,973 copies/mL (<30- >750,000 copies/mL), respectively. Highly active antiretroviral therapy (HAART) use increased from 87.5% during the 1st study year to 98.5% by the end of the study. During a median follow-up of 334 days, 16% (30) of the subjects died and 2 (6%) developed CMV disease. No deaths were attributable to CMV disease; 4 subjects who died developed CMV prior to death. Baseline HIV viral load and final CD4 cell count were significantly and independently associated with mortality. Detectable plasma CMV DNA PCR was an independent predictor of death even after adjusting for HIV RNA level and CD4 cell count prior to death (P = 0.038). In contrast, whole blood CMV hybrid capture did not predict mortality. The CMV assays neither collectively nor individually were found to be associated with the few cases of CMV disease.

CONCLUSIONS

In patients with AIDS and seropositive for CMV, detection of CMV viremia with plasma CMV DNA PCR was predictive of death and provided additional prognostic information on the risk of all cause-mortality beyond that obtained with CD4 cell count and HIV viral load testing alone. Detection of CMV viremia by plasma with CMV DNA PCR in patients with AIDS, particularly those with low CD4 cell counts, provides additional rationale for optimization of antiretroviral therapy and consideration for preemptive anti-CMV therapy.

Real-time PCR assays based on distinct genomic regions for cytomegalovirus reactivation following hematopoietic stem cell transplantation

Real-time PCR has many advantages compared with antigenemia and qualitative PCR assays for detecting cytomegalovirus (CMV) infection in patients following SCT. However, the procedure used in each report was not standardized. This study compares the CMV load detected by real-time PCR assays amplifying distinct genomic regions. Real-time PCR assays based on US17, UL65, immediate early protein (IE) and glycoprotein B(gB) were selected and comparisons were made between each genomic region, and with antigenemia and nested PCR (IE region) in 18 SCT patients. The CMV load detected by real-time PCR using all combinations of primers targeting distinct genomic regions and by antigenemia assays correlated well. However, US17 and UL65-PCR could detect CMV earlier than gB-PCR, antigenemia and nested PCR assays. In longitudinal analysis, gB-PCR demonstrated a trend for showing a lower viral load in some patients than US17-, UL65- and IE-PCR. Moreover, the results suggest that a cutoff level of 500 copies/ml might be used to decide when to initiate treatment. We propose that monitoring should be carried out using real-time PCR assays targeting the US17 region and that a CMV load of 500 copies/ml could be used as a cutoff value for initiating treatment in patients following SCT, receiving immunoglobulin prophylaxis.

Comparison of a duplex quantitative real-time PCR assay and the COBAS Amplicor CMV Monitor test for detection of cytomegalovirus

A duplex quantitative real-time PCR (qPCR) assay was designed to detect both the polymerase gene (pol) and the glycoprotein gene (gB) of cytomegalovirus (CMV). The detection limit of the qPCR was determined to be 1 to 3 copies/reaction and the linear measure interval was 10(3) to 10(8) copies/ml. The qPCR system was compared to the COBAS Amplicor CMV Monitor test (COBAS) by an analysis of 138 plasma samples. Both systems detected CMV in 71 cases and had negative results for 33 samples. In addition, 34 samples were positive by qPCR and negative by the COBAS assay, but in no case was the COBAS result positive and the qPCR result negative. Thus, qPCR detected 48% more positive cases than the COBAS method. For samples with > or = 10(5) copies/ml by qPCR, a saturation effect was seen in the COBAS assay and quantification required dilution. Copy numbers for pol and gB by qPCR generally agreed. However, the reproducibility of qPCR assays and the need for an international standard are discussed. Discrepant copy numbers for pol and gB by qPCR were found for samples from two patients, and sequence analysis revealed that the corresponding CMV strains were mismatched at four nucleotide positions compared with the gB fragment primer sequences. In conclusion, a duplex qPCR assay in a real-time format facilitates quantitative measurements and minimizes the risk of false-negative results.

Quantitative real-time PCR with automated sample preparation for diagnosis and monitoring of cytomegalovirus infection in bone marrow transplant patients

BACKGROUND

In bone marrow and stem cell transplant patients, the widespread use of preemptive cytomegalovirus (CMV) antiviral therapy necessitates faster, more precise, and more sensitive quantitative laboratory methods for serial viral load monitoring.

METHODS

We developed a novel CMV viral load assay using real-time PCR of plasma DNA prepared by an automated robotic workstation. Fluorescent hybridization probes directed at the glycoprotein B (gB) gene (or EcoRI D region) of CMV were used to detect and quantify PCR products. The beta-globin gene was amplified in parallel to control for the efficiency of the extraction and PCR steps.

RESULTS

The assay was linear (R = 0.999) from a lower detection limit of 125 copies/mL to 5 x 10(9) copies/mL with a PCR efficiency of 1.975 (gB) or 2.02 (EcoRI D). The viral loads determined by PCRs directed at these two different viral targets were no different (n = 53; R = 0.928). The interassay CV was 3.5%, and the intraassay CV was 1-4%. Compared with a commercially available quantitative competitive PCR assay (Roche MONITOR; R = 0.59), the mean CMV viral load by real-time PCR was 3.1 times higher (mean ratio; P = 0.002). The diagnostic sensitivity and specificity of the real-time assay were 96% and 100%, respectively (n = 147), compared with 74% and 98% for a qualitative PCR assay (Roche AMPLICOR). On a subset of samples, the diagnostic sensitivity of viral culture was no greater than 50% (n = 44). Of 1115 clinical referral samples from 252 patients, 10% of the samples and 18% of the patients had low-level CMV viremia (median, 500 copies/mL). In this predominantly (85%) bone marrow transplant testing cohort, serial CMV viral load results were the predominant clinical trigger for the initiation, monitoring, and cessation of preemptive antiviral therapy.

CONCLUSIONS

The combination of automated DNA preparation and semiautomated real-time fluorescent PCR detection allows for a sensitive, precise, and accurate high-throughput assay of CMV viral load that can be used as the laboratory trigger for preemptive antiviral therapy.

Co-detection and discrimination of six human herpesviruses by multiplex PCR-ELAHA

BACKGROUND

Herpesviruses are a significant cause of human morbidity. Traditional approaches to the identification of these viruses require infectious or at least antigenic virus. Multiplex PCR (mPCR) is capable of simultaneously amplifying a range of targets from a single preparation of nucleic acids and when combined with a suitable detection assay, it is capable of discriminating each of the amplicons.

OBJECTIVES

Several methods have been described in the literature, however, they lack one or more significant design features required to suitably control a routinely applied nucleic acid amplification assay. We aimed to design a multiplex herpesvirus PCR that could co-amplify eight human herpesvirus targets plus an internal control (IC) molecule in a single tube.

STUDY DESIGN

Primers were designed to target the DNA polymerase genes of each of the human herpesviruses. Synthetic controls were developed to act as templates for the evaluation of assay sensitivity and specificity and for development of an in-house competitive quantitative PCR. Amplicon was discriminated using a simplified enzyme linked amplicon hybridisation assay (ELAHA).

RESULTS AND CONCLUSIONS

For routine diagnostic use we reduced the number of herpesviral targets from 8 to 6 in order to maintain adequate clinical sensitivity. The ELAHA proved more sensitive than agarose gel electrophoresis. Additionally, 36 cytomegalovirus positive patients were examined with an in-house quantitative PCR-ELAHA which was developed to confirm that that the mPCR's co-detection limit of 10(2) copy of synthetic template per millilitre was relevant for use in detecting virus from clinical samples. The mPCR-ELAHA was then applied to the screening of 174 patient specimens resulting in a specificity of 98% and a sensitivity of 93%. This preliminary study demonstrated that the mPCR-ELAHA was a complete approach to the detection of herpesviruses from a range of clinical samples and disease states.

Real-time PCR assay compared to nested PCR and antigenemia assays for detecting cytomegalovirus reactivation in adult T-cell leukemia-lymphoma patients

We analyzed the efficiency of the quantitative real-time PCR assay for cytomegalovirus (CMV) reactivation in adult T-cell leukemia-lymphoma (ATL) patients and compared the results with those obtained with qualitative nested PCR and antigenemia assays. The viral load obtained by the real-time PCR assay closely paralleled the number of antigen-positive cells obtained with the antigenemia assay. Real-time PCR revealed that a large number of DNA copies could be present even in samples assessed as negative or low in antigen-positive cells (0 to 10 antigen-positive cells/50,000 cells) by antigenemia assay. CMV copy numbers did not differ between the negative and low-antigen-positive groups. When the input concentration for real-time PCR assay was 2,500 to 5,000 copies/ml, the positivity rate for the nested PCR assay was 47.3%, while the positivity rate was more than 90% at an input concentration of >/=50,000 copies/ml. Real-time PCR is more sensitive than the antigenemia and nested PCR assays. Moreover, real-time PCR was able to detect CMV reactivation earlier than the antigenemia and nested PCR assays through the use of longitudinal analysis in four ATL patients with CMV pneumonia. In longitudinal assessments, analysis of the results suggested that a cutoff level of 5,000 copies/ml might be used to initiate treatment. Real-time PCR is more suitable for monitoring CMV reactivation in ATL patients than the antigenemia and nested PCR assays. CMV viral loads of 5,000 copies/ml are proposed as the cutoff for initiating antiviral therapy in ATL patients.

Cytomegalovirus (CMV) and human immunodeficiency virus (HIV) burden, CMV end-organ disease, and survival in subjects with advanced HIV infection (AIDS Clinical Trials Group Protocol 360)

We undertook a prospective study to analyze cytomegalovirus (CMV) end-organ disease (EOD) in subjects with advanced human immunodeficiency virus (HIV) infection. Of 403 individuals without prior CMV EOD who were followed up for a median of 151 weeks, 56 died and 21 developed CMV EOD. Twenty of the subjects with CMV EOD had CD4 cell counts of < or =50 cells/mm3 and HIV RNA level of >10,000 copies/mL of plasma at baseline; in these 20 subjects, an increase of CMV DNA level to greater than the quantification limits was associated with CMV EOD. A CD4 cell count of < or =100 cells/mm3 and an HIV RNA level of >10,000 copies/mL of plasma at baseline, a CMV DNA level of >200 copies/mL of blood during follow-up, or development of CMV EOD were all associated with decreased survival. HIV-infected subjects with CD4 cell counts of < or =50 cells/mm3 and HIV RNA levels of >10,000 copies/mL of plasma should have blood fractions screened for CMV DNA; if CMV DNA is detected, CMV prophylaxis might be considered.

Quantitative analysis of CMV DNA in children the first year after liver transplantation

CMV infection is a major problem after solid organ transplantation especially in children where primary infection is more common than in adults. Early diagnosis is critical and might be facilitated by quantitative analysis of CMV DNA in blood. In this retrospective study of 18 children who had a liver transplantation 1995-2000, serum samples were analysed by Cobas Amplicor Monitor (Roche). Four patients developed symptomatic CMV infection at a mean time of 4 wk after transplantation. They showed maximum CMV DNA levels in serum of 26 400, 1900, 1300 and 970 copies/mL, respectively. In comparison, CA Monitor was positive, at a low level (415 copies/mL), in one of 11 patients with asymptomatic (4) or latent (7) infection. CMV IgM was detected at significant levels (> or =1/80) in all four patients with symptomatic, and in one with asymptomatic CMV infection. Eight patients were given one or several courses of ganciclovir. Five of these lacked symptoms of CMV disease, and had low (415 copies/mL) or undetectable CMV DNA in serum. The data suggest that quantitative analysis of CMV DNA may be of value in early identification of CMV disease and for avoiding unnecessary antiviral treatment.

Comparison of molecular tests for detection and quantification of cell-associated cytomegalovirus DNA

A cell-based standard was developed to compare the COBAS Amplicor CMV Monitor test, the Hybrid Capture System CMV DNA test, and the NucliSens CMV test. The standard was prepared by infecting human foreskin fibroblasts (HFFs) with cytomegalovirus (CMV) strain AD169 at low multiplicity of infection (0.03) and harvesting the cells at 6 h postinfection. Buffy coat cells were added to produce concentrations of from 0 to 10(5) HFFs per 10(6) total cells. Five laboratories performed the Amplicor PCR test and two laboratories performed the NucliSens and Hybrid Capture tests. The Amplicor PCR test was 1.5 to 2.0 log(10) more sensitive than the Hybrid Capture test. The specificities of the Amplicor PCR and Hybrid Capture tests were 100 and 93.8%, respectively. The linear range of the Amplicor PCR and Hybrid Capture tests were 2 to 4.48 log(10) and 3.48 to at least 5.0 log(10) CMV target cells, respectively. The standard deviations of the Amplicor PCR and Hybrid Capture tests varied throughout their linear range, and for both tests the variability was greater for lower concentrations of input CMV DNA. These data allow the direct comparison of viral load values between the Amplicor and Hybrid Capture tests. The analytical sensitivity of the NucliSens test could not be determined by using the 6-h standard, because the low multiplicity of infection and short culture time did not allow for adequate transcription of pp67 late mRNA measured in the test. Extending the incubation time of the standard to 24 h increased the analytical sensitivity of the NucliSens test to 3.0 log(10) target cells.

Monitoring of cytomegalovirus infection in solid-organ transplant recipients by an ultrasensitive plasma PCR assay

Early and accurate monitoring of cytomegalovirus (CMV) infection in solid-organ transplant recipients is of major importance. We have assessed the potential benefit of an ultrasensitive plasma-based PCR assay for renal transplant recipients. The pp65 CMV antigen (pp65 Ag) assay using leukocytes was employed as a routine test for the monitoring of CMV in 23 transplant recipients. We compared the pp65 antigenemia with the CMV load quantified by an ultrasensitive PCR (US-PCR) with a limit of detection of 20 CMV DNA copies/ml of plasma. CMV infection was detected in 215 (67%) of 321 plasma samples by the US-PCR compared with 124 (39%) of 321 samples by the pp65 Ag assay. The US-PCR assay permitted the detection of CMV infection episodes following transplantation a median of 12 days earlier than the pp65 Ag assay. Moreover, during CMV infection episodes, DNA detection by the US-PCR was consistently positive, whereas false negative results were frequently observed with the pp65 Ag assay. We found a good correlation between the two assays, and the peak viral loads were significantly higher in patients with CMV-related complications (median, 5000 DNA copies/ml) than in those without symptoms (1160 DNA copies/ml) (P = 0.048). In addition, patients that did not require preemptive therapy based on the results of the pp65 assay had CMV loads significantly lower (median, 36 DNA copies/ml) than those that needed treatment (median, 4703 DNA copies/ml) (P < 0.001). These observations provided cutoff levels that could be applied in clinical practice. The ultrasensitive plasma-based PCR detected CMV infection episodes earlier and provided more consistent results than the pp65 Ag assay. This test could improve the monitoring of CMV infection or reactivation in renal transplant recipients.

Automated extraction and quantification of human cytomegalovirus DNA in whole blood by real-time PCR assay

The measurement of human cytomegalovirus (HCMV) DNA in blood is becoming the standard method for monitoring HCMV infection in immune-suppressed and unsuppressed patients. As various blood compartments can be used, we have compared the HCMV DNA measured in whole blood (WB), peripheral blood leukocytes (PBL), and plasma by real-time PCR. We tested 286 samples: HCMV DNA was extracted automatically from WB and PBL with the MagNA Pure instrument (Roche Molecular Biochemicals) and manually from plasma samples. The HCMV DNA from WB, PBL, and plasma was measured by real-time Light Cycler PCR. Primers and probe were located in the UL 83 region. HCMV DNA was detected more frequently in WB (88.5%) than in the PBL (65.7%) (P < 0.0001) or the plasma (55.2%) (P < 0.0001). There was a good correlation between the positive results in WB and in PBL (r = 0.68; P < 0.0001), and 3.15 log(10) genome copies in 200000 PBL, equivalent to the threshold value of 50 pp65-positive polymorphonuclear cells per 200000 leukocytes, was equivalent to 3.4 log(10) genome copies in 200 microl of WB. WB was shown to be suitable for automated extraction and the quantitation of HCMV DNA by real-time Light Cycler PCR by analysis of serial samples from representative patients of various populations. This system may be very useful for monitoring of immune-suppressed and unsuppressed patients.

Comparison of LightCycler-based PCR, COBAS amplicor CMV monitor, and pp65 antigenemia assays for quantitative measurement of cytomegalovirus viral load in peripheral blood specimens from patients after solid organ transplantation

In order to evaluate the LightCycler-based PCR (LC-PCR) as a diagnostic assay technique, a classical pp65 antigenemia assay and the commercially available COBAS Amplicor CMV Monitor (CACM) assay were compared to the LC-PCR assay for the detection and quantitation of cytomegalovirus (CMV) load in 404 parallel specimens of peripheral blood from 66 patients after solid organ transplantation. A good correlation existed among these three assays (r congruent with 0.6, P < 0.0001). The LC-PCR assay was the most sensitive (54% of specimens positive) compared to the CACM (48.6%) and the pp65 antigenemia (26%) assays. The LC-PCR assay detected all samples found positive by using both the CMV pp65 antigenemia assay and the CACM assay. The LC-PCR also had the widest dynamic range (from 250 to 10(7) DNA copies/ml of plasma). No cross-reactions were found among CMV and Epstein-Barr virus, varicella-zoster virus, or herpes simplex virus in the LC-PCR by using amplification with specifically designed primer pairs. Precision, expressed as the coefficient of variation, was <3% with standard DNA from cell cultures and between 6.55 and 14.1% with clinical specimens in repeat LC-PCR runs. One run of the LC-PCR took half of the time required for the semiautomated CACM procedure. Because of its sensitivity, specificity, cost-effectiveness, and simplicity, the LC-PCR assay could replace the pp65 antigenemia and the CACM assays as the preferred technique for the surveillance, diagnosis, and monitoring of response of CMV diseases in high-risk populations.