Quantitation of cytomegalovirus: methodologic aspects and clinical applications

Modeling costs and cost-effectiveness of different CMV management strategies in liver transplant recipients as a support for current and future decision making

OBJECTIVES

To develop a generic decision-analytic model to predict health and economic outcomes of different management options for cytomegalovirus (CMV) infection and disease in liver transplant patients.

METHODS AND DATA

The model considers different CMV management strategies, thereby emphasizing the important difference between infection and disease. The first strategy starts with prophylaxis prior to transplantation, followed by preemptive treatment if infection, based on positive CMV diagnostic tests, is confirmed. The second strategy is a preemptive strategy consisting of only testing followed by preemptive treatment. Finally, in the wait-and-treat strategy, antiviral treatment is only started when clinical signs of CMV disease appear. Management and resource-use data were obtained from clinical experts in large transplant centers in France, Germany, and the United Kingdom. Cost data were collected from the health care payer's perspective. A Bayesian revision technique was applied to distinguish effectiveness of current management options for CMV infection vs. CMV disease, an aspect that is currently underreported in literature.

RESULTS

CMV prophylaxis in liver transplant recipients is generally more cost-effective than preemptive and wait-and-treat strategies. In order of importance, changes in drug costs, drug efficacy, specificity of CMV testing, cost of hospitalization, probability of CMV relapse and baseline CMV risk are the most important factors influencing the cost-effectiveness.

CONCLUSION

This model describes different strategies applied for management of CMV in liver transplant patients and is useful both for current decision making, optimal disease management, and assessment of future research targets.

Multiplex, quantitative, real-time PCR assay for cytomegalovirus and human DNA

We created a multiplex, quantitative, real-time PCR assay that amplifies cytomegalovirus (CMV) and human DNA in the same reaction tube, allowing for a viral load determination that is normalized to measured human DNA. The assay targets a conserved region of the CMV DNA polymerase gene that is not affected by known drug resistance mutations. All 36 strains of CMV detected by culture or qualitative PCR in a population of lung transplant recipients were detected. The assay detected 1 to 10 copies of CMV plasmid DNA. The analytic sensitivity was not affected by the presence of DNA from 10(6) human cells but was reduced approximately 10-fold by alkaline lysates of leukocyte preparations. CMV quantitation was linear over a range of 10(1) to 10(6) copies. The intraassay and interassay coefficients of variation were 29 and 40%. Human DNA was regularly detected in patient plasma samples, and the amount was increased by storage of blood at room temperature before plasma separation and by plasma separation techniques that allowed leukocyte contamination. Applied to whole blood, the assay provides a measurement of CMV DNA in relation to cellular content without a need for cell counting procedures. Applied to plasma, the assay can reveal artifactual increases in plasma CMV levels resulting from leukocyte contamination. Further study of the utility of this assay to monitor patient populations at risk for CMV disease is warranted.

Human cytomegalovirus as a direct pathogen: correlation of multiorgan involvement and cell distribution with clinical and pathological findings in a case of congenital inclusion disease

The human cytomegalovirus (HCMV), a member of the Herpesviridae, is the most frequent cause of congenital virus infections and a major cause of morbidity and mortality in immunocompromised patients. Due to the lack of an appropriate animal model, insight into the pathogenesis of HCMV infections originates primarily from in situ examination of HCMV-infected tissues. Although in immunocompromised adults such tests are complicated frequently by the presence of additional misleading pathogens, the absence of additional pathogens renders congenital inclusion disease the most suitable access for investigation of pathogenetic aspects of HCMV infections. Immunohistochemical examination of tissue sections from a boy with fatal congenital inclusion disease was undertaken to detect the extent of multiorgan and cell involvement. Adrenal gland, bone marrow, diencephalon, heart, kidney, liver, lung, pancreas, placenta, small bowel and spleen were included in this study. Detection of virus antigens from different phases of viral replication revealed that all investigated organs were infected by HCMV. Simultaneous detection of cell type specific marker molecules showed that a variety of cell types stained positive for HCMV antigens including endothelial cells, epithelial cells, smooth muscle cells, mesenchymal cells, hepatocytes, monocytes/macrophages and granulocytes. The lung, the pancreas, the kidneys and the liver were the major target organs with a high number of HCMV infected cells. This correlated with multiorgan failure as the cause of death and strongly indicates direct pathogenetic effects of HCMV.

High variability between results of different in-house tests for cytomegalovirus (CMV) monitoring and a standardized quantitative plasma CMV PCR assay

A total of 2,718 blood samples were analyzed in five virological laboratories for the presence of cytomegalovirus (CMV) by in-house tests and one standardized plasma PCR assay. Results from in-house tests showed remarkable variability. Detection of CMV pp65 antigen or DNA from cells was more sensitive than that by plasma CMV PCR assay.

Dose-adjusted preemptive therapy for cytomegalovirus disease based on real-time polymerase chain reaction after allogeneic hematopoietic stem cell transplantation

We have prospectively evaluated the efficacy of real-time PCR-guided preemptive therapy for CMV diseases in allogeneic hematopoietic stem cell transplant recipients with grades II-IV acute GVHD. The dose of ganciclovir was adjusted according to the viral load determined by real-time polymerase chain reaction (PCR). On detecting CMV reactivation in the plasma, ganciclovir was initiated at a dose of 5 mg/kg body weight once daily, and the dose was increased to twice daily if viral load continued to increase after initiating ganciclovir. In 39 evaluable patients, CMV reactivation assessed by real-time PCR became positive in 30 (77%). One developed CMV gastroenteritis before PCR became positive. Thus the remaining 29 patients were treated preemptively with ganciclovir. The dose of ganciclovir was increased in 12 patients (41%) of preemptively treated patients for increasing viral load. CMV diseases were diagnosed in two patients (one gastroenteritis and one retinitis), and late CMV disease was diagnosed in one patient (gastritis). The treatment was generally well-tolerated, but three patients (10%) developed neutropenia (neutrophil count less than 1.0 x 10(9)/l). In conclusion, real-time PCR-guided preemptive therapy with decreased dose of ganciclovir is feasible and does not increase the frequency of CMV diseases if the dose is adjusted according to the viral load.

Diagnosis of cytomegalovirus infections by qualitative and quantitative PCR in HIV infected patients

A high incidence of cytomegalovirus (CMV) infections is observed in Brazil. These viruses are causatives of significant morbidity and mortality among patients with advanced human immunodeficiency virus (HIV) infection. This work, shows the application of a PCR on determination of CMV load in the buffy coat and plasma. We analyzed the samples of 247 HIV infected patients in order to diagnose CMV infection and disease. We developed a semi-quantitative PCR that amplifies part of the glycoprotein B (gB) gene of CMV. The semi-quantitative PCR was carried out only in positive clinical samples in a qualitative PCR confirmed by a nested-PCR. CD4 lymphocyte count, HIV viral load and CMV disease symptom were correlated with CMV load. CMV genome was detected in the buffy coat of 82 of 237 (34.6%) patients, in 10 of these the CMV load was determined varying between 928 and 332 880 viral copies/microg DNA. None of these 237 patients developed any suggestive manifestation of CMV disease. For the other 10 HIV infected patients selected based on the suspicion of CMV disease, CMV genome was detected in only one case. This patient presented a high CMV load, 8 000 000 copies/microg DNA, and developed a disseminated form of CMV disease including hepatitis and retinitis. Our results were greatly influenced by the impact of the highly active antiretroviral therapy that reduced incidence of CMV viremia and occurrence of CMV disease in the HIV infected patients.

Real-time PCR quantification of human cytomegalovirus DNA in amniotic fluid samples from mothers with primary infection

A real-time PCR assay was developed to quantify human cytomegalovirus (HCMV) DNA in amniotic fluid (AF) samples collected from 30 pregnant women with primary HCMV infection as detected either from HCMV-immunoglobulin G (IgG) seroconversion or by the presence of HCMV-specific IgG and IgM associated with a low IgG avidity. Clinical information available for each case included ultrasonographic examination and fetal or newborn outcome. HCMV infection of fetuses or newborns was confirmed for the 30 studied cases. AF samples were subdivided into three groups. In group A (n = 13), fetuses presented major ultrasound abnormalities, and pregnancy was terminated. In group B (n = 13), fetuses had normal ultrasound findings, the pregnancy went to term, and the newborns were asymptomatic at birth. In group C (n = 4), fetuses had no or minor ultrasonographic signs, and pregnancy was terminated. The HCMV DNA load values in AF samples were significantly higher in group A (median, 2.8 x 10(5) genome equivalents [GE]/ml) than in group B (median, 8 x 10(3) GE/ml) (P = 0.014). Our findings suggest that HCMV load level in AF samples correlates with fetal clinical outcome but might also be dependent on other factors, such as the gestational age at the time of AF sampling and the time elapsed since maternal infection.

CMV DNA in blood and CSF of HIV infected patients

Cytomegalovirus (CMV) infection frequently affects the central nervous system in HIV infected patients. Varied clinical manifestations of CMV disease make virological detection of CMV essential for proper diagnosis and treatment. Thus, in patients in different stages of HIV-induced disease, we attempted to detect cell associated and free, non cell associated CMV DNA in cerebrospinal fluid (CSF) and in peripheral blood mononuclear cells (PBMCs). Twenty-six blood samples were collected from 22 patients included in the study. Nine of these blood samples were tested in pair with the concomitant CSF sample for the presence of CMV DNA by a commercial hybridization test. CMV serostatus and avidity of IgG antibodies were detected by a commercial ELISA test. CMV DNA was present in the cells found in CSF in all but one of the AIDS patients, independently of the presence of neurological symptoms, suggesting that it represented a marker of advanced immunodeficiency, rather than of the specific CMV-related disease. Cell-associated CMV DNA in CSF tested positive even in the samples negative for cell-free CMV DNA in the CSF, and with no detectable CMV DNA in the PBMCs of concomitant blood sample. We believe that searching for CMV DNA in different compartments of CSF merits further attention.

Development and evaluation of an internally controlled semiautomated PCR assay for quantification of cell-free cytomegalovirus

Quantification of circulating human cytomegalovirus (HCMV) is useful in clinical contexts such as virological surveillance of bone marrow transplant recipients and monitoring of antiviral therapy. This report describes an internally controlled, quantitative, semiautomated, HCMV genome assay that was developed primarily to measure HCMV DNA in the plasma of severely leucopaenic patients. It exhibits greater sensitivity, wider dynamic range and higher sample throughput than a number of previously described commercial and "in-house" assays. Viral DNA extraction from EDTA plasma samples was automated using a BioRobot 9604 (Qiagen). HCMV strain AD169 was used to prepare a calibration curve and murine cytomegalovirus (MCMV) strain Smith was added as internal control to all calibration standards and test samples. Amplification was performed using a set of primers based on the HCMV UL50 region, capable of amplifying both human and murine CMV. The yield of biotinylated polymerase chain reaction (PCR) products was estimated using HCMV-specific and MCMV-specific enzyme-labelled probes and automated chemiluminescence detection. Log-transformed HCMV-to-MCMV signal ratios were calculated and used for quantification of test samples against simultaneously extracted MCMV-spiked calibration standards. Evaluation of the assay sensitivity by Probit analysis demonstrated a 95% probability of detection at 100 HCMV genomes per ml of plasma; the dynamic range was shown to be > or = 4 log(10). A total of 315 samples from 61 bone marrow transplant patients were analysed by both the quantitative PCR (qPCR) and by a previously validated nested nonquantitative PCR (NQPCR). A high level of concordance (90%) was observed between the two assays, although the qPCR assay exhibited slightly greater sensitivity.

Quantitation of CMV by real-time PCR in transfusable RBC units

BACKGROUND

CMV is one of the most significant pathogens infecting immunocompromised individuals. CMV is transmissible through transfusion of blood components. The goal of this study was to measure CMV levels in RBC units using a sensitive and quantitative DNA amplification assay.

STUDY DESIGN AND METHODS

An assay to measure CMV load was developed by using real-time PCR to target the major immediate early viral gene. A probe (TaqMan, Applied Biosystems) was used to confirm product specificity and to permit quantitation of CMV in blood samples on a sequence detection system (ABI Prism 7700, Applied Biosystems).

RESULTS

The assay was shown to be accurate, linear, and sensitive to as few as five copies of CMV DNA per PCR. The assay was applied to aliquots of RBC units from 203 healthy donors, 110 of whom were seropositive for CMV. CMV DNA was not detected in any of the 203 RBC samples.

CONCLUSION

The findings statistically imply that at least 98.5 percent of RBC units have a CMV load of less than 250 copies per mL. Future clinical studies on larger numbers of units are required to determine the utility of real-time PCR in evaluating the risk of CMV transmission and in confirming the efficacy of WBC reduction.

Cytomegalovirus infections

Over the past two decades, there has been an escalation in the number of patients undergoing immunosuppressive therapy following solid organ or bone marrow transplantation, as well as a dramatic increase in the incidence of AIDS. As a result, human cytomegalovirus (HCMV)--once considered a neonatal disease--has captured great interest and importance as a major pathogen in both immunocompromised and immunocompetent patients. Like other members of herpesviridae family, HCMV establishes latency in myeloid lineage cells with potential for reactivation. The natural history of HCMV infection can be divided into primary infection, latency, and reinfection. This review article briefly discusses the molecular pathogenesis of HCMV, then focuses on the clinical picture of this disease, with emphasis on the skin pathology. Diagnostic methods and treatments are also discussed.

Infections diagnosed in the first year after pediatric stem cell transplantation

BACKGROUND

Cumulative incidence of infections in the first year posttransplantation in adult patients has been well-described. Such description is less than complete for pediatric stem cell transplantation (SCT) patients. Further among those patients who have been infected, analysis of risk factors for infection has not been well-described for a large cohort of pediatric SCT patients.

METHODS

We conducted a retrospective cohort study of infections in the first year after SCT at Duke University Medical Center. We recorded all infections in the first year after transplantation. We determined incidences for 6 categories of infection: gram-negative rods; gram-positive cocci; yeast species; Aspergillus sp.; adenovirus; and cytomegalovirus. We determined incidences based on type of transplant and days post transplantation. We also completed bivariable and multivariable analysis of risk factors [neutropenia, graft vs. host disease (GVHD) and GVHD treatment] for infection type among those children who were infected.

RESULTS

We evaluated 510 transplants in 485 children. There were 584 infections in the first year after transplantation. During the first 30 days posttransplantation, type of transplantation did not predict incidence of infection or type of infection. After 30 days children who received unrelated cord blood transplant and matched unrelated donor transplant were at much higher risk of infection than were patients who received autologous, matched sibling or haploidentical transplant (P < 0.001). Patients who received unrelated cord blood or matched unrelated donor transplantation were at higher risk of aspergillosis (P = 0.002), candidiasis (P = 0.005) and adenovirus (P < 0.0001) but not cytomegalovirus (P = 0.18). In analysis of risk factors among those infected, patients with aspergillosis were more likely to have severe GVHD: multivariable 1 year risk ratio, 7.5; 95% confidence interval, 3.0, 18.4. Neutropenia was more strongly associated with gram-negative rod infection than any other type of infection.

CONCLUSIONS

The incidence of infection immediately after transplantation did not differ significantly by type of transplant in this pediatric population. Type of transplant predicted increased incidence of infection 30 days posttransplantation and increased incidence of infection with several organisms traditionally associated with a high mortality rate in the transplant population.

Performance characteristics of an automated PCR assay for the quantification of cytomegalovirus DNA in plasma

The COBAS Amplicor CMV Monitor test (Roche Diagnostics), an automated polymerase chain reaction (PCR) assay for the quantification of cytomegalovirus (CMV) DNA in plasma samples, was evaluated in a routine diagnostic laboratory. Using cell culture-derived CMV and CMV-negative human plasma, the linear detection range of the assay as well as its intra-and inter-assay variabilities were assessed. The study design allowed distinguishing variations in results related to amplification and detection from those caused by differences in the efficiency of DNA extraction. The assay was able to identify the majority of samples correctly as positive with CMV DNA concentrations above the limit of detection. However, the reported values were often twofold or more different from the (theoretical) input, which could be explained partly by inefficient DNA extraction. The following values were computed for the coefficients of determination R(2): inter-assay variability excluding DNA extraction, R(2)=0.982; including DNA extraction, R(2)=0.977; intra-assay variability excluding DNA extraction, R(2)=0.992; including DNA extraction, R(2)=0.992. On balance, the test has acceptable within-run and between-run reproducibility. It therefore allows the comparison of results obtained at different time-points as well as in different laboratories, e.g. in multi-centre studies.

Lack of transmission to polymorphonuclear leukocytes and human umbilical vein endothelial cells as a marker of attenuation of human cytomegalovirus

The development of a human cytomegalovirus (HCMV) vaccine for the prevention of perinatal disease is urgently needed. However, markers of HCMV attenuation are not defined at present. An in vitro model for the study of interactions of HCMV-infected human fibroblasts and peripheral blood polymorphonuclear leukocytes showed that (1) known laboratory-adapted HCMV strains as well as cell culture-adapted HCMV isolates were not transmitted to polymorphonuclear leukocytes; (2) each of the 80 HCMV recent isolates was consistently transmitted to polymorphonuclear leukocytes as both infectious virus and viral components (nucleic acid and proteins); and (3) all 15 polymorphonuclear leukocyte-tropic strains tested thus far were also endothelial cell-tropic. The in vitro transmissibility to polymorphonuclear leukocytes (and endothelial cells) is proposed as a surrogate marker of pathogenicity of HCMV strains. It seems reasonable to assume that a HCMV strain candidate for a vaccine be verified as deprived of the transfer property to polymorphonuclear leukocytes (and endothelial cells) before involvement in clinical trials assessing safety and immunogenicity.

Early detection of cytomegalovirus (CMV) infection in bone marrow transplant patients by reverse transcription-PCR for CMV spliced late gene UL21.5: a two site evaluation

BACKGROUND

Bone marrow transplant (BMT) patients at risk of developing cytomegalovirus (CMV) pneumonitis are identified routinely by the early detection of virus in blood. For early diagnosis of CMV infection, the RNA-based approach demonstrates advantages when compared with the current CMV antigen and DNA detection methods.

OBJECTIVES

We have evaluated our previously developed reverse transcription-polymerase chain reaction (RT-PCR) to a spliced late CMV gene (SLG; J. Virol. Methods 56 (1996), 139) to monitor CMV infection in BMT patients at two clinical sites. The diagnostic value of the SLG RT-PCR was compared with the routine CMV antigen and DNA detection methods.

STUDY DESIGN

Weekly blood samples from BMT patients were tested for CMV during the first 3 months post-transplant. The qualitative SLG RT-PCR, semiquantitative DNA PCR, and viral antigen tests were compared. The RNA and DNA PCR results were analysed in terms of their temporal relationship and consistency of CMV detection and compared with CMV infection diagnosed by viral antigen tests.

RESULTS

Of the 101 BMT recipients studied, 25 developed CMV antigenemia and/or DNAemia resulting in symptomatic infection in two patients. All CMV PCR-positive patients were either CMV seropositive pretransplant or received marrow from seropositive donor. The highest incidence of CMV infection was seen in seropositive recipients (R+) irrespective of the donor's status. Detection of CMV infection by SLG RNA preceded CMV DNA detection by 0-2 weeks (median 1 week) and CMV antigen detection by 0-8 weeks (median 3 weeks). Once detected, the SLG RNA remained consistently positive before antiviral treatment was commenced. Both the SLG RNA and CMV DNA detection methods had the same clinical sensitivity, specificity, positive and negative predictive values of 100, 94, 80 and 100%, respectively.

CONCLUSIONS

The RT-PCR for SLG RNA proved to be the earliest indicator of CMV infection in BMT patients demonstrating a sustained pattern of CMV detection during the 3 months post-transplant period. Although very similar in its diagnostic performance to CMV DNA PCR the SLG RNA RT-PCR does not require quantitation and provides an efficient and ongoing indication of active CMV infection.

Prevention of cytomegalovirus infection and disease after lung transplantation: results using a unique regimen employing delayed ganciclovir

BACKGROUND

Many lung transplant programs employ lengthy regimens of IV ganciclovir therapy to prevent disease due to cytomegalovirus (CMV). In 1994, we introduced a regimen of delayed ganciclovir prophylaxis for CMV infection. This consisted of 2 weeks of IV ganciclovir therapy, initiated 3 to 4 weeks after transplantation, with subsequent viral monitoring and preemptive therapy as needed. When not receiving ganciclovir, patients received oral acyclovir, 800 mg tid, for 6 months. CMV-seronegative patients with seropositive donors also received four doses of CMV hyperimmune globulin. This study analyzes the CMV outcomes of 54 patients who received the delayed regimen compared to 33 historical control subjects who received only acyclovir prophylaxis (n = 28) or oral acyclovir and 2 to 4 weeks of ganciclovir early after transplantation (n = 5).

METHODS

CMV detection was by shell vial culture or IgG seroconversion; after 1996, CMV detection was by blood antigenemia. The diagnosis of CMV disease also required a typical clinical syndrome or pathologic evidence of CMV. The main outcome was the actuarial incidence of CMV infection and disease. In order to account for the effect of other important risk factors for CMV infection, the time to CMV infection and disease was also studied as dependeant variables in a Cox proportional-hazard analysis, with the delayed regimen and other important risk factors as independent variables.

RESULTS

The delayed regimen reduced the actuarial incidence of CMV infection from 80 to 48% (p < 0.001) and CMV disease from 31 to 10% (p < 0.01). No seropositive patient receiving the delayed regimen developed CMV disease. Twelve of the 54 patients in the study group required additional IV antiviral treatment, but the total use of ganciclovir averaged only 18 days per patient. In a Cox proportional-hazards model, the use of delayed ganciclovir was the only factor that showed a significant association with freedom from CMV infection (hazard ratio [HR], 0.43; 95% confidence interval [CI], 0.24 to 0.75; p = 0.003) and CMV disease (HR, 0.29; 95% CI, 0.10 to 0.86; p = 0.03).

CONCLUSION

A regimen of CMV prophylaxis employing 2 weeks of IV ganciclovir initiated 3 to 4 weeks after lung transplantation followed by virologic monitoring and preemptive therapy as needed provides good protection against CMV disease.

Comparative quantitation of cytomegalovirus (CMV) DNA in solid organ transplant recipients with CMV infection by using two high-throughput automated systems

Cytomegalovirus (CMV) DNA quantitation in clinical specimens is progressively becoming a cornerstone in the diagnosis and management of CMV infection in the immunocompromised host. We evaluated two automated and reproducible PCR tests, the LightCycler (Roche Molecular Biochemicals, Indianapolis, Ind.) and the COBAS AMPLICOR CMV Monitor (Roche Diagnostics, Pleasanton, Calif.), for the detection of CMV DNA in blood samples from transplant recipients with CMV infection as determined by shell vial culture. Following a log transformation analysis, the mean CMV DNA in plasma (PL), whole blood (WB), peripheral blood leukocytes (PBL), and peripheral blood mononuclear cells (PBMC) using the LightCycler was 6.79 copies per ml, 7.23 copies per ml, 6.38 copies per 2 x 10(6) cells, and 6.27 copies per 2 x 10(6) cells, respectively. This compares to 7.86 copies per ml, 8.37 copies per ml, 7.59 copies per 2 x 10(6) cells, and 7.44 copies per 2 x 10(6) cells, respectively, using COBAS AMPLICOR CMV Monitor. While higher CMV DNA levels were observed for the various blood compartments analyzed using COBAS AMPLICOR CMV Monitor, a high degree of correlation was evident between the two automated systems (jackknife correlation r = PL 0.77 [95% confidence interval (CI); 0.64, 0.90], WB 0.77 [95% CI; 0.62, 0.92], PBL 0.77 [95% CI; 0.67, 0.88], and PBMC 0.81 [95% CI; 0.72, 0.89], all P < 0.001). Therefore, we conclude that either automated diagnostic system is accurate for CMV DNA quantitation.

Diagnosis and monitoring of human cytomegalovirus diseases in patients with human immunodeficiency virus infection by use of a real-time PCR assay

We used a real-time PCR assay to measure human cytomegalovirus (HCMV) DNA load in whole blood and plasma of 70 patients who were infected with human immunodeficiency virus type 1. Break points of 3.0 x 10(3) copies/mL in whole blood and 1.0 x 10(3) copies/mL in plasma were well-correlated with the existence of definite HCMV disease (sensitivity, 93% and 86%; specificity, 89% and 85%; positive predictive value, 70% and 63%; and negative predictive value, 98% and 95%, respectively). In patients with < 50 cells/microL of CD4(+) T lymphocytes, positive predictive values increased to 78% and 71%, respectively. The viral loads of all patients who received anti-HCMV therapy declined to < or =2.0 x 10(2) copies/mL in parallel with the improvement of clinical symptoms. These findings show that the HCMV DNA load quantified with our method is a useful tool for diagnosis of HCMV diseases and for monitoring the disease activity in patients infected with HIV-1.

Differences between the quantitative antigenemia assay and the cobas amplicor monitor quantitative PCR assay for detecting CMV viraemia in bone marrow and solid organ transplant patients

The relationship between quantitative PCR (COBAS Amplicor CMV Monitor, Roche Diagnostics) and quantitative antigenemia (Monofluor pp65, Sanofi Diagnostics) was examined for monitoring CMV viraemia. A total of 469 specimens from immunocompromised haematology and solid organ transplant patients were tested by quantitative antigenemia and qualitative PCR. Quantitative PCR (QPCR) was performed on the 245 specimens in which CMV DNA was detected by qualitative PCR. To exclude any effect due to specific anti-CMV treatment, analysis of antigenemia and QPCR results was only performed on the 164 of 245 specimens collected from patients not on ganciclovir or foscarnet treatment. Forty seven specimens had <400 CMV copies/mL and a negative antigen result, four specimens were antigen positive (all between 1 to 10 positive CMV cells/2 x 10(5) leucocytes) and had <400 CMV copies/mL. Fifty-one specimens had a CMV viral load > or = 400 copies/mL and a negative antigen result and 62 specimens had a CMV viral load > or = 400 copies/mL and a positive antigen. The viral load was shown to be as high as 43,000 copies/mL in some patients with a negative antigen and occurred in non-neutropenic patients. The correlation coefficient for antigen and QPCR results for specimens from bone marrow transplant patients, was 0.69 with an average CMV viral load of 3,200 copies/mL (SEM = 800) and an average antigen of nine positive CMV cells/2 x 10(5) leucocytes (SEM = 3). In the corresponding solid organ transplant group, the correlation coefficient for antigen and QPCR results was 0.71 with an average CMV viral load of 9,900 copies/mL (SEM = 2,100) and an average antigen of 26 positive CMV cells/2 x 10(5) leucocytes (SEM = 6). Both the average viral load and the average antigen result in specimens from solid organ transplant patients, were significantly higher than the average viral load and antigen result in the corresponding group of bone marrow transplant patients (Two-Sample-for-Means z-Test, P = 0.001 and P = 0.003, respectively). The differences in the kinetics of the two assays in monitoring CMV and their ability to predict CMV disease was also assessed in a sub-group of patients. In conclusion, the two assays used in this study do not always show parallel changes in CMV viral load, but may be complementary for the diagnosis and management of CMV disease. The observation that non-neutropenic patients can have a high viral load in plasma and a negative antigenemia has implications for laboratories using antigenemia alone to monitor patients for CMV disease.

Clinical utility of viral quantification as a tool for disease monitoring

The possibility to detect viral DNA or RNA in a quantitative manner has already contributed significantly to the management and diagnosis of viral infections, as well as to the understanding of virus-host interactions. New developments in amplification techniques based on real-time detection, as well as automation of the whole process, will soon be introduced in a diagnostic laboratory setting, thereby enabling a rapid turnaround time to generate both quantitative and qualitative results. New guidelines for disease management, as well as extensive quality control and standardization programs must be introduced.

An indicator cell assay for detection of human cytomegalovirus based on enhanced green fluorescent protein

An indicator cell line (ML-UL54-EGFP) for the detection of human cytomegalovirus (HCMV) by a simple and direct method was developed. The stable line was constructed by introducing into mink lung cells an expression cassette that contains the enhanced green fluorescent protein (EGFP) reporter gene under the control of an HCMV-inducible promoter. The promoter was from the upstream region of the HCMV UL54 (pol) gene, an early gene promoter that is activated in the early phase of HCMV infection. Following infection with HCMV for 48 h, the stable line expressed well detectable level of the EGFP as observed under a fluorescence microscope. The sensitivity of the indicator cell assay is at least comparable with that of a plaque assay as assessed with a panel of HCMV strains. There were no detectable fluorescent cells after inoculations with several viruses other than HCMV, indicating high specificity. Analysis with flow cytometry revealed that the induced fluorescence from the infected cells was proportional to the titer of HCMV inoculated, making it possible to quantify HCMV infectious particles. In summary, the EGFP-based indicator cell line is of potential use for rapid detection and quantification of HCMV in clinical specimens.

Cross-reactivity of Epstein-Barr virus-specific immunoglobulin M antibodies with cytomegalovirus antigens containing glycine homopolymers

Timely and reliable detection of acute primary human cytomegalovirus (HCMV) infection is important in prenatal screening programs and for differential diagnosis of infectious mononucleosis-like disease. Enzyme-linked immunosorbent assays (ELISAs) based on HCMV proteins enable the sensitive detection of immunoglobulin M (IgM) antibodies during primary infection. However, concerns have been raised about possible cross-reactivities of the HCMV antigens used for the design of such ELISAs with IgM antibodies induced by Epstein-Barr Virus (EBV). In this study we investigated whether IgM antibodies generated during acute EBV infection reacted with recombinant HCMV antigens. Serum samples from patients with primary EBV infection frequently scored positive when tested in different HCMV IgM ELISAs, irrespective of whether conventional or recombinant antigens were used for the design of the HCMV IgM assays. Such cross-reactive IgM antibodies were found to be directed against short glycine-rich motifs contained within the nonstructural HCMV proteins pUL44 and pUL57. Further analyses revealed that these glycine-rich motifs were major antigenic domains for IgM antibodies induced during HCMV infection. Their deletion from recombinant proteins abrogated reactivity with IgM synthesized during HCMV infection. EBV-induced IgM antibodies that reacted with HCMV antigens showed similar kinetics of reactivity in HCMV- or EBV-specific assays in the course of primary EBV infection, indicating that the two populations of antibodies were highly overlapping. The results demonstrate that primary EBV infection leads to the induction of IgM antibodies that specifically bind to widely used diagnostic antigens of HCMV. This has to be considered in the interpretation of HCMV-specific IgM assays.

Evaluation of CMV viral load using TaqMan CMV quantitative PCR and comparison with CMV antigenemia in heart and lung transplant recipients

BACKGROUND

Quantitative assessment of cytomegalovirus (CMV) infection using the antigenemia test has been used to monitor CMV infection in heart and lung transplant patients enabling a preemptive treatment strategy. However, the method is labour intensive, samples have to be processed within a few hours and requires skilled interpretation. A comparative prospective evaluation of a real-time TaqMan CMV quantitative PCR (QPCR) with the CMV antigenemia was undertaken.

METHODS

A real-time quantitative TaqMan CMV PCR from EDTA bloods was developed. In this study 25 heart transplant and single-lung transplant patients were monitored posttransplantation by antigenemia and TaqMan CMV QPCR. CMV DNA extracted from EDTA blood was amplified by TaqMan QPCR using primers and probe designed from the CMV glycoprotein B (gB) gene. Quantification of the genome copies is extrapolated from a standard curve generated from amplification of quantified standards.

RESULTS

Antigenaemia levels and TaqMan CMV QPCR genome copies showed a linear correlation between the two assays (R=0.843, P=0.001). A clinically significant threshold of 50 CMV pp65 antigen positive polymorphonuclear leucocytes (PMNLs) per 200 000 cells previously reported was used to extrapolate an equivalent value of 40 000 (log 4.6) genome copies per ml of blood for the TaqMan CMV QPCR.

CONCLUSIONS

The TaqMan system enables a rapid high-throughput of samples. The TaqMan CMV QPCR can be used as an accurate and robust alternative to the antigenemia test to predict CMV disease and to monitor effectiveness of treatment.

CMV infection of liver transplant recipients: comparison of antigenemia and molecular biology assays

BACKGROUND

CMV is a major clinical problem in transplant recipients. Thus, it is important to use sensitive and specific diagnostic techniques to rapidly and accurately detect CMV infection and identify patients at risk of developing CMV disease. In the present study, CMV infection after liver transplantation was monitored retrospectively by two molecular biology assays - a quantitative PCR assay and a qualitative NASBA assay. The results were compared with those obtained by prospective pp65 antigenemia determinations.

MATERIALS AND METHODS

87 consecutive samples from 10 liver transplanted patients were tested for CMV by pp65 antigenemia, and CMV monitor and NASBA pp67 mRNA assay.

RESULTS

CMV infection was detected in all patients by antigenemia and CMV monitor, whereas NASBA assay identified only 8/10 patients with viremia. Furthermore, CMV infection was never detected earlier by molecular biology assays than by antigenemia. Only 5/10 patients with CMV infection developed CMV disease. Using a cut off value of 8 cells/50,000, antigenemia was found to be the assay that better identified patients at risk of developing CMV disease. However, the kinetics of the onset of infection detected by NASBA and CMV monitor seemed to have better identified patients at risk of developing CMV disease. Furthermore, before onset of disease, CMV pp67 mRNA was found to have similar or better negative and positive predictive values for the development of CMV disease.

CONCLUSIONS

The present data, suggests that the concomitant use of antigenemia and pp67 mRNA assay gives the best identification of patients at risk of developing CMV disease.

Association of tumour necrosis factor alpha and interleukin 6 levels with cytomegalovirus DNA detection and disease after renal transplantation

Cytokines such as tumour necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) are thought to be important in the pathogenesis of post-transplant cytomegalovirus (CMV) disease. CMV infection increases the production of TNF-alpha and IL-6. Conversely, TNF-alpha switches on the replication of CMV. To study the association of these two cytokines with CMV activity and disease, TNF-alpha and IL-6 levels were assayed in plasma samples taken serially from three groups of renal transplant recipients. Group A (n = 12) had CMV disease and syndrome; Group B (n = 11) had detectable CMV DNA in plasma or peripheral blood leucocytes without disease, i.e., presumed asymptomatic CMV infection, and Group C (n = 11) had no detectable CMV DNA nor disease. The median peak TNF-alpha levels in patients with CMV disease (Group A) were significantly higher than that in Group B or Group C (P < 0.02) whereas the median peak IL-6 levels in group C patients were significantly lower than that in group A (P < 0.04) or group B (P < 0.03). A TNF-alpha level of above 100 pg/ml was significantly associated with CMV disease and high plasma CMV load (> 10,000 copies/ml). IL-6 levels above 15 pg/ml were significantly associated with CMV DNA detection, but not with CMV disease or elevated CMV load. High levels of TNF-alpha or IL-6 were not associated with CMV donor/recipient serostatus, HHV-6 or HHV-7 DNA detection, immunosuppressive regimen or rejection episodes. The role of TNF-alpha in the pathogenesis of CMV disease deserves further investigation.

New developments in the diagnosis of maternal and congenital CMV infection

Recent advances in the screening of pregnant women with Cytomegalovirus (CMV) IgM, CMV IgG and CMV IgG avidity serologic tests, has led to a more accurate diagnosis of CMV infection. When serologic screening is performed early in gestation, it is possible to identify those women at risk of intrauterine transmission of the virus, i.e., those women with a primary CMV infection, who should be enrolled in prenatal diagnosis. The use of quantitative PCR on amniotic fluid from pregnant women at 21-22 weeks of gestation in prenatal diagnosis is an effective diagnostic tool to distinguish between CMV infection and CMV disease in the fetus and newborn. Quantitative PCR on peripheral blood leukocytes from CMV infected newborns can be used to monitor viral load, especially during treatment with ganciclovir. These advances in serology and quantitative virology should lead to more accurate diagnosis of maternal and congenital CMV infection.

Viral infections after renal transplantation

Viral infections are a leading cause of posttransplantation morbidity and mortality. A number of recent developments have altered our understanding and management of these disorders. The pathogenetic roles of several viruses, including human herpesviruses 6 and 8, have been newly established. Molecular-based diagnostic tests now make more rapid diagnosis possible. The licensing of new potent antiviral agents offers a wider choice of drugs for viral prophylaxis and treatment. The use of more potent immunosuppressive agents is responsible in part for the increasing incidence of some viral infections, but this varies among drugs, and individual viruses differ in their sensitivity to immunosuppressive agents. This review summarizes the natural history, diagnosis, prevention, and treatment of many common viral infections after renal transplantation.

Intra-monocyte pathogens delineate autism subgroups

Immune panels of many autism-spectrum children reveal signs of atypical infections and shifted cell counts. In conjunction with trait-related cerebral hypometabolism and hypoperfusion, these findings suggest a hypothesis: Several autism-spectrum subgroups derive from intra-monocyte pathogens such as measles virus, cytomegalovirus, human herpesvirus 6, and Yersinia enterocolitica. Furthermore, with much inter-child variation, their effects manifest as diminished hematopoiesis, impaired peripheral immunity, and altered blood-brain barrier function often accompanied by demyelination. In some such children, one or more of these pathogens persists as a chronic-active, seemingly subclinical infection etiologically significant to the child's autistic traits. Within these subgroups, immune impairments and atypical infections may be treatable.

New developments in the management of cytomegalovirus infection and disease after renal transplantation

The clinical management of cytomegalovirus infection and disease in renal transplant recipients has recently been significantly improved with the availability of data on prophylaxis with oral ganciclovir and valacyclovir. In addition, significant progress in early diagnosis and the quantitation of viral load has been achieved. The influence of novel immunosuppressants on the clinical course of cytomegalovirus infection has been clarified to some extent by recent clinical data. The identification of risk factors for cytomegalovirus disease beyond seroconstellation and immunosuppression is an ongoing process that might lead to a more targeted use of antiviral agents, given the risk of ganciclovir resistance. The understanding of the effects of cytomegalovirus on long-term graft outcome still needs to be deepened in order to design cytomegalovirus-specific interventions to improve graft survival.

Development of a real-time PCR procedure including an internal control for the measurement of HCMV viral load

Human cytomegalovirus (HCMV) infections are frequent in immuno-compromised patients. The recent development of real-time PCR procedures that allow the rapid quantification of genome load will be helpful for accurate monitoring of these infections. Two extraction procedures were evaluated using 30 blood samples that were processed pure and diluted (1/10). Repeatability and reproducibility of the quantitative PCR procedure using an internal control for amplification were analysed, and its sensitivity compared to a qualitative PCR procedure using 50 HCMV culture positive blood samples. The real-time PCR and qualitative PCR procedures were positive in 46 and 48 of the samples tested, respectively. Discrepancies were observed for samples with a low viral load. The sensitivity of the real-time PCR procedure was evaluated at 500 HCMV DNA copies per ml of sera. The use of an internal control concomitantly processed during the HCMV quantification did not alter the sensitivity of the procedure, and was relevant for the detection of putative PCR inhibitors that may interfere with the amplification process. This procedure was used to measure genome load in two bone marrow transplant patients with HCMV disease, confirming that this new PCR procedure should be used widely for diagnosing and monitoring HCMV infections in transplant patients.

Respiratory tract infections in cytomegalovirus-excreting and nonexcreting infants

BACKGROUND

There is evidence of an immunosuppressive effect of cytomegalovirus (CMV), and CMV has been claimed to be a copathogen in respiratory tract infections (RTI). We therefore studied the significance of CMV viral load in infants with RTI, compared the frequency of infection with respiratory viruses and followed the course of RTI in CMV-excreting vs. nonexcreting infants.

METHODS

We examined 201 infants consecutively admitted to the Department of Pediatrics for RTI. At admission nasopharyngeal aspirates, throat swabs and urine were examined for CMV, and nasopharyngeal aspirates were examined for respiratory viruses.

RESULTS

In these patients 23.3% had CMV in the urine, 15.3% had CMV in the throat and 10.9% had CMV in the nasopharynx; 26.2% excreted CMV in at least one site. No relationship was found between CMV viral load and clinical symptoms. Infection with respiratory viruses was as common in infants excreting CMV as in nonexcreting infants. Symptoms and the course of infection were not different in the two groups except that CMV-excreting infants had a significantly higher frequency of rhonchi at admission (P = 0.007) and a tendency for longer duration of cough (P = 0.06).

CONCLUSION

CMV viral load was not related to clinical symptoms. The frequency of infection with common respiratory viruses in infants was independent of CMV excretion. The course of infection was not more complicated in infants excreting CMV; however, a higher frequency of rhonchi was demonstrated in patients with CMV.

Patterns of cytomegalovirus infection in simultaneous kidney-pancreas transplant recipients receiving tacrolimus, mycophenolate mofetil, and prednisone with ganciclovir prophylaxis

BACKGROUND

The impact of tacrolimus (TAC), mycophenolate mofetil (MMF) and steroid immunosuppression on cytomegalovirus (CMV) infection in combination with ganciclovir prophylaxis in simultaneous kidney-pancreas transplantation (SKPT) has not been well studied.

METHODS

A retrospective analysis was made of 75 SKPTs performed between 1 January 1996 and 7 January 1999. All patients received ganciclovir for 3 months, but CMV donor (D)+ / recipient (R)- patients received ganciclovir for 6 months.

RESULTS

16/74 (22%) were CMV D+/R-, 25 (33%) D+/R+, 16 (22%) D-/R+, and 17 (23%) D-/R- (1 patient with unknown donor serology was excluded). The mean time to CMV infection was 198 days post-transplant. The incidence of either CMV infection or tissue invasive CMV disease was 16/74 (22%), including 9 (12%) with CMV infection and 7 (10%) CMV disease. The one-year patient, kidney, and pancreas graft survival rates were 91%, 89%, and 83%, respectively. The mean follow-up was 29 months (minimum of 12 months). CMV infection was not associated with an increased incidence of graft failure or mortality. The D+/R- group had the highest incidence of CMV infection (44%) compared with the other serologic groups (17%, P=0.02). Concurrent CMV and rejection occurred more frequently in the D+/R- than the other serologic groups (25% vs. 7%, P=0.03). The D-/R- group had the best outcomes, with no CMV infection, improved kidney graft survival at the end of follow-up (82% vs. 72%, P=0.04) and the highest event-free survival (no CMV infection, rejection, or graft loss) when compared to the other groups (76% vs. 33%, P<0.01).

CONCLUSIONS

Compared to previous studies, ganciclovir prophylaxis delayed the onset and reduced the severity of CMV infection in patients receiving TAC, MMF, and steroids. Despite ganciclovir prophylaxis, CMV seronegative patients receiving CMV D+ organs had worse outcomes than seronegative recipients receiving CMV D- organs.

Clinical evaluation of a new recombinant antigen-based cytomegalovirus immunoglobulin M immunoassay in liver transplant recipients

BACKGROUND

Human cytomegalovirus (CMV) is a significant cause of morbidity and mortality among transplant recipients. Monitoring transplant recipients by CMV IgM serology has been questioned by several studies due to the reported insensitivity of serologic tests relative to antigen detection methods.

METHODS

In this retrospective study, we have evaluated the performance of the new recombinant antigen-based Abbott AxSYM CMV IgM assay and compared it with CMV culture technique in a cohort of 40 liver transplant recipients who did not receive antiviral prophylaxis.

RESULTS

The sensitivity, specificity, and positive and negative predictive values for detection of CMV disease by the AxSYM CMV IgM assay were 90.0%, 60.0%, 69.2%, and 85.7%, respectively, and by culture the values were 100%, 55.0%, 69.0%, and 100%, respectively. Detection of CMV IgM occurred before or at the time of CMV disease in only R+ recipients.

CONCLUSION

Although this assay is a sensitive test for CMV-specific IgM, detection of CMV IgM preceded detection of virus by culture in patients only when the liver transplant recipient was CMV immune before transplantation (R+).

Quantification of human cytomegalovirus DNA by real-time PCR

A quantitative real-time PCR assay was developed to measure human cytomegalovirus (HCMV) DNA load in peripheral blood leukocytes (PBLs). The HCMV DNA load in PBLs was normalized by means of the quantification of a cellular gene (albumin). The results of the real-time PCR assay correlated with those of the HCMV pp65-antigenemia assay (P < 0.0001).

Direct quantification of human cytomegalovirus immediate-early and late mRNA levels in blood of lung transplant recipients by competitive nucleic acid sequence-based amplification

The dynamics of active human cytomegalovirus (HCMV) infection was monitored by competitive nucleic acid sequence-based amplification (NASBA) assays for quantification of IE1 (UL123) and pp67 (UL65) mRNA expression levels in the blood of patients after lung transplantation. RNA was isolated from 339 samples of 13 lung transplant recipients and analyzed by the quantitative IE1 and pp67 NASBA in parallel with pp65 antigenemia and serology. Rapid increases in IE1 RNA exceeding 10(4) copies per 100 microl of blood were associated with active infection, whereas lower levels were suggestive for abortive, subclinical viral activity. Any positive value for pp67 RNA was indicative for active infection, and quantification of pp67 mRNA did not give additional diagnostic information. The onset of IE1-positive NASBA preceded pp67 NASBA and was earlier than the pp65 antigenemia assay, confirming previous studies with qualitative NASBA. Effective antiviral treatment was reflected by a rapid disappearance of pp67 mRNA, whereas IE1 mRNA remained detectable for longer periods. Quantification of IE1 might be relevant to monitor progression of HCMV infection but should be validated in prospective studies.

Evaluation of diagnostic methods for the detection of cytomegalovirus in recipients of allogeneic stem cell transplants

BACKGROUND

Although several diagnostic methods are available for the surveillance of patients at risk of human cytomegalovirus (CMV) infection and disease, little data is available on their comparative performances in the diagnostic setting.

OBJECTIVES

To compare different assays for CMV detection, especially assays based on (quantitative) DNA and mRNA detection.

STUDY DESIGN

Eight allogeneic bone marrow and stem cell transplant recipients at high risk for developing CMV disease (donor CMV-negative, recipient positive) were regularly tested for 7-20 weeks post-transplant by spin-amplification rapid culture from urine (viruria), antigenemia (pp65 assay), pp67 mRNA in whole blood (NASBA), and CMV DNA both qualitatively (in-house PCR, whole blood) and quantitatively (in-house PCR, plasma; Cobas Amplicor CMV Monitor Test, plasma and whole blood; Hybrid Capture, whole blood).

RESULTS

Four patients (50%) suffered CMV reactivation during follow-up. Out of 104 sample dates, 41 (39.4%) yielded a positive CMV result in at least one assay. Out of the 28 samples tested by all assays, the highest percentage of positive results was obtained with the in-house quantitative PCR (60.7%), followed by the Hybrid Capture system (39.3%), the Cobas Amplicor CMV Monitor Test, plasma version (35.7%), the Cobas Amplicor CMV Monitor Test, whole blood version (32.1%), in-house qualitative PCR (28.6%), and the mRNA assay (21.4%). Viruria was positive in one sample and pp65 antigenemia was found in two samples.

CONCLUSIONS

Despite a considerable incidence of CMV reactivations, pre-emptive anti-CMV chemotherapy prevented the development of CMV disease with the exception of one case. The molecular assays had superior sensitivity to conventional ones. The antigenemia assay proved unsuitable for the surveillance of hematological transplant patients. However, none of the tests recognized all timepoints with CMV reactivation. Further comparative studies are needed to determine their respective diagnostic values.

Preventing opportunistic infections after hematopoietic stem cell transplantation: the Centers for Disease Control and Prevention, Infectious Diseases Society of America, and American Society for Blood and Marrow Transplantation Practice Guidelines and beyond

This review presents evidence-based guidelines for the prevention of infection after blood and marrow transplantation. Recommendations apply to all myeloablative transplants regardless of recipient (adult or child), type (allogeneic or autologous) or source (peripheral blood, marrow or cord blood) of transplant. In Section I, Dr. Dykewicz describes the methods used to rate the strength and quality of published evidence supporting these recommendations and details the two dozen scholarly societies and federal agencies involved in the genesis and review of the guidelines. In Section II, Dr. Longworth presents recommendations for hospital infection control. Hand hygiene, room ventilation, health care worker and visitor policies are detailed along with guidelines for control of specific nosocomial and community-acquired pathogens. In Section III, Dr. Boeckh details effective practices to prevent viral diseases. Leukocyte-depleted blood is recommended for cytomegalovirus (CMV) seronegative allografts, while ganciclovir given as prophylaxis or preemptive therapy based on pp65 antigenemia or DNA assays is advised for individuals at risk for CMV. Guidelines for preventing varicella-zoster virus (VZV), herpes simplex virus (HSV) and community respiratory virus infections are also presented. In Section IV, Drs. Baden and Rubin review means to prevent invasive fungal infections. Hospital design and policy can reduce exposure to air contaminated with fungal spores and fluconazole prophylaxis at 400 mg/day reduces invasive yeast infection. In Section V, Dr. Sepkowitz details effective clinical practices to reduce or prevent bacterial or protozoal disease after transplantation. In Section VI, Dr. Sullivan reviews vaccine-preventable infections and guidelines for active and passive immunizations for stem cell transplant recipients, family members and health care workers.

Quantitative analysis of cytomegalovirus (CMV) viremia using the pp65 antigenemia assay and the COBAS AMPLICOR CMV MONITOR PCR test after blood and marrow allogeneic transplantation

The performance of a commercially available qualitative PCR test for plasma (AMPLICOR CMV Test; Roche Diagnostics) and a quantitative PCR test for plasma and leukocytes (COBAS AMPLICOR CMV MONITOR Test; Roche Diagnostics) was evaluated with samples from 50 blood or marrow allogeneic transplant recipients who received short courses of sequential ganciclovir therapy (2 weeks intravenously followed by 2 weeks orally) based on a positive cytomegalovirus (CMV) pp65 antigenemia (AG) assay. The number of persons with a positive CMV test was significantly higher for leukocyte-based assays (AG, 67.5%; PCR, 62.5%) compared to both quantitative and qualitative PCR tests of plasma (42.5 and 35%, respectively). One person developed CMV disease during the study despite a negative AG assay; in this particular case, all PCR assays were found to be positive 10 days before his death. There was a trend for earlier positivity after transplantation and more rapid negativity after initiation of ganciclovir for the tests performed on leukocytes. The mean number of CMV copies as assessed by PCR was significantly higher in leukocytes than in plasma (P = 0.02). Overall, excellent agreement (kappa coefficient, >0.75) was found only between the two PCR assays (qualitative and quantitative) based on plasma. These results suggest that either the pp65 AG assay or the COBAS AMPLICOR CMV MONITOR Test using leukocytes could be used to safely monitor CMV viremia in related allogeneic blood or marrow transplant recipients. Such a strategy will result in preemptive treatment for about two-thirds of the persons with a relatively low rate (<33%) of secondary viremic episodes following short courses of ganciclovir therapy.

Quantification of cytomegalovirus DNA in BAL fluid: a longitudinal study in lung transplant recipients

STUDY OBJECTIVES

Cytomegalovirus (CMV) infection is common in patients receiving solid organ transplants, and it is associated with increased morbidity as well as risk for development of chronic rejection. A rapid and sensitive diagnostic method would improve the therapeutic management of CMV infection, including the monitoring of treatment effects. We investigated whether longitudinal determinations of CMV DNA quantities in BAL fluid could be useful for this purpose.

DESIGN

CMV DNA levels in 340 BAL samples from 35 consecutive lung transplant recipients were studied during a median of 18 months. Seventeen (49%) of the patients developed CMV disease with pneumonitis. Twenty-seven CMV disease episodes were diagnosed.

RESULTS

Patients with CMV disease had a significantly higher mean level of CMV copies per milliliter BAL fluid (1,120 +/- 4,379) compared with those without (180 +/- 1,177, p < 0.01). Viral load as well as acute rejection requiring treatment (>/= A2) were independent risk factors associated with CMV disease. Differences between the groups concerning HLA-DR matching, basic immunosuppressive therapy, and CMV serologic status D/R -/+ vs D/R +/+ were not significant. A diagnostic definition of normality based on the mean level of all episodes without CMV disease +2 SD would discriminate only 9 of the 27 CMV episodes.

CONCLUSIONS

Although the viral load is increased during episodes of clinical CMV disease in lung transplant recipients, the quantitative PCR assessment of CMV DNA in BAL fluid is not discriminative enough to be useful as a diagnostic tool for CMV disease.

Monitoring four herpesviruses in unrelated cord blood transplantation

Cord blood transplantation, which has lower risk of graft-versus-host disease than bone marrow transplantation, might have higher risk of infections. A system to quantify four herpesviruses, CMV, human herpesvirus 6 (HHV6), EBV, varicella-zoster virus using the real-time PCR assay was established and applied for prospective viral load monitoring in three recipients undergoing cord blood transplantation. CMV and HHV6 were detected in peripheral blood from all three recipients, while EBV was detected in two. Varicella-zoster virus was not detected at all. At the peak of HHV6 or CMV, each patient showed virus-related symptoms. During the pre-transplant period, CMV DNA was detected in two recipients who later developed CMV-related diseases. These observations indicate that our system is not only useful for managing herpesviruses infections in transplant recipients, but also a powerful method for clarifying the relationships between the viral load and clinical symptoms.

Predictive value of quantitative PCR-based viral burden analysis for eight human herpesviruses in pediatric solid organ transplant patients

Human herpesviruses can cause significant morbidity and mortality in pediatric solid organ transplant recipients. It was hypothesized that viral burden quantification by polymerase chain reaction using an internal calibration standard could aid in distinguishing between viral disease and latency. Here we report the results of a 2-year prospective study of 27 pediatric solid organ (liver, kidney, or heart) transplant recipients in which multiple samples were analyzed for levels of all eight human herpesviruses by internal calibration standard-polymerase chain reaction. Herpes simplex viruses 1 and 2, varicella-zoster virus, and Kaposi's sarcoma-associated herpesvirus were not detected in any of these samples. Human herpesvirus types 6 and 7 were detected in half of the patients, but were present at low levels, similar to those found in reference populations. Epstein-Barr virus (EBV) and cytomegalovirus (CMV) were detected in 89% and 56% of the patients, respectively. Viral burden analysis suggested distinct patient populations for CMV, with a natural cutoff of 10,000 viral targets/ml blood strongly associated with disease. In some cases, a dramatic increase in CMV levels preceded clinical evidence of disease by several weeks. EBV viral burden was relatively high in the only patient presenting with an EBV syndrome. However, two other patients without evidence of EBV disease had single samples with high EBV burden. Rapid reduction in both EBV and CMV burden occurred with antiviral treatment. These data suggest that viral burden analysis using internal calibration standard-polymerase chain reaction for CMV, and possibly other herpesviruses, is an effective method for monitoring pediatric transplant patients for significant herpesvirus infection and response to therapy.

The postoperative course of gamma-glutamyl transpeptidase--a marker of cytomegalovirus (CMV) replication risk?

Cytomegalovirus (CMV) infection is a common complication in the postoperative course of liver transplantation. In order to start early prophylactic therapy, but to avoid unnecessary treatment, or expensive screening, a desirable goal in post-transplant monitoring is to find appropriate markers in standard laboratory diagnostics. In the present study, the results of a 6-week CMV replication monitoring schedule by the pp65 antigenemia assay in 100 liver graft recipients were included. The activities of transaminases, glutamate dehydrogenase and gamma-glutamyl transpeptidase (gamma-GT) were measured by routine laboratory methods. In contrast to the transaminases, the serum activity of gamma-GT increased during the first postoperative week. The maximum levels were 246 +/- 211 U/l in patients without (n = 46) and 140 +/- 89 U/l in patients with early CMV replication (n = 54; p = 0.02). Patients with gamma-GT levels below 200 U/l on the 5th postoperative day (n = 72) had a CMV replication risk of 65%, whereas those patients with gamma-GT levels above this threshold had a risk of 30% (n = 28; p = 0.0007; relative risk = 2.9). These findings provide a routinely usable marker for the identification of patients at an increased risk of CMV replication. It can be considered that these phenomena may be caused by an additional immunosuppressive effect of the CMV virus.