New strategies for prevention and therapy of cytomegalovirus infection and disease in solid-organ transplant recipients

Artemisinin-derived dimers have greatly improved anti-cytomegalovirus activity compared to artemisinin monomers

BACKGROUND

Artesunate, an artemisinin-derived monomer, was reported to inhibit Cytomegalovirus (CMV) replication. We aimed to compare the in-vitro anti-CMV activity of several artemisinin-derived monomers and newly synthesized artemisinin dimers.

METHODS

Four artemisinin monomers and two novel artemisinin-derived dimers were tested for anti-CMV activity in human fibroblasts infected with luciferase-tagged highly-passaged laboratory adapted strain (Towne), and a clinical CMV isolate. Compounds were evaluated for CMV inhibition and cytotoxicity.

RESULTS

Artemisinin dimers effectively inhibited CMV replication in human foreskin fibroblasts and human embryonic lung fibroblasts (EC(50) for dimer sulfone carbamate and dimer primary alcohol 0.06+/-0.00 microM and 0.15+/-0.02 microM respectively, in human foreskin fibroblasts) with no cytotxicity at concentrations required for complete CMV inhibition. All four artemisinin monomers (artemisinin, artesunate, artemether and artefanilide) shared a similar degree of CMV inhibition amongst themselves (in microM concentrations) which was significantly less than the inhibition achieved with artemisinin dimers (P<0.0001). Similar to monomers, inhibition of CMV with artemisinin dimers appeared early in the virus life cycle as reflected by decreased expression of the immediate early (IE1) protein.

CONCLUSIONS

Artemisinin dimers are potent and non-cytotoxic inhibitors of CMV replication. These compounds should be studied as potential therapeutic agents for the treatment of CMV infection in humans.

Lower incidence of cytomegalovirus infection with everolimus versus mycophenolate mofetil in de novo cardiac transplant recipients: a randomized, multicenter study

Cytomegalovirus (CMV) is a major cause of infectious complications following cardiac transplantation, severely affecting short- and long-term outcomes. A 12-month, multicenter, randomized, open-label study in de novo cardiac transplant patients was undertaken to compare the efficacy, renal function, and safety of everolimus plus reduced cyclosporine versus mycophenolate mofetil (MMF) plus standard cyclosporine (ClinicalTrials.gov NCT00150046). CMV-specific data was prospectively collected on infections, laboratory evidence, CMV syndrome, and CMV disease. In total, 176 patients were randomized (everolimus 92; MMF 84). Use of CMV prophylaxis was similar between groups (everolimus 20.8%; MMF 24.0%). Patients in the everolimus arm had a significantly lower incidence of any CMV event (8.8% versus 32.5% with MMF, P<0.001), CMV infection as an adverse event (4.4% versus 16.9%, P=0.011), laboratory evidence of CMV (antigenemia 7.7% versus 27.7%, P<0.001; polymerase chain reaction assay 2.2% versus 12.0%, P=0.015), and CMV syndrome (1.1% versus 8.4%, P=0.028). In the donor (D)+/recipient (R)+and D-/R+ subgroups, even after adjusting for use of prophylaxis, the CMV event rate remained significantly lower with everolimus than with MMF (P=0.0015 and P=0.0381, respectively). In conclusion, de novo cardiac transplant recipients experienced lower rates of CMV infection, CMV syndrome, or organ involvement on an everolimus-based immunosuppressant regimen compared with MMF.

A commutable cytomegalovirus calibrator is required to improve the agreement of viral load values between laboratories

BACKGROUND

Viral load testing for cytomegalovirus (CMV) is an important diagnostic tool for the management of transplant recipients and immunocompromised individuals; however, inconsistency among laboratories in quantitative measurements of viral load limits interinstitutional comparisons. These inconsistencies stem from the lack of assays cleared by the US Food and Drug Administration, the absence of international standards, the wide variety of CMV-extraction and -detection methods, and differences in materials used for calibration. A critical component of standardization is the use of calibrators that are traceable and commutable.

METHODS

Bland-Altman plots and prediction ellipses were used to test the commutability of 2 CMV calibrators for 2 different quantification methods.

RESULTS

Tests with 2 methods showed 1 calibrator to be commutable and the other to be noncommutable. The results for the commutable calibrator were within the 95% prediction interval of the clinical samples in the Bland-Altman plot and within the 95% prediction ellipse for a simulated commutable calibrator, whereas the results for the noncommutable calibrator were not within these prediction intervals. When used to calibrate patient results, only the commutable calibrator, the OptiQuant CMV(tc) Calibration Panel, significantly improved the comparability of viral loads for the 2 different measurement methods.

CONCLUSIONS

This study demonstrates that an important goal in the effort to improve healthcare for patients with CMV-related disease is the establishment of traceable and commutable reference materials, including both calibrators and controls. .

Valganciclovir for cytomegalovirus prevention in solid organ transplant patients: an evidence-based reassessment of safety and efficacy

BACKGROUND

Several anti-viral drugs have demonstrated efficacy in preventing Cytomegalovirus (CMV) infections in solid organ transplant (SOT) patients. The recently approved valganciclovir is the most commonly used and most expensive drug for CMV prevention. The safety and efficacy data have been drawn from a single trial. We hypothesized that valganciclovir may not be as safe as nor more effective than other therapies for CMV prevention.

METHODS

All experimental and analytical studies that compared valganciclovir with other therapies for prevention of CMV infection after SOT were selected. Based on meta-analytic and multivariate regression methodologies we critically analyzed all available evidence.

FINDINGS

Nine studies were included (N = 1,831). In trials comparing valganciclovir with ganciclovir, the risk for CMV disease is 0.98 (95% Confidence Interval (95%CI) 0.67 to 1.43; P = 0.92; I(2) = 0%). Valganciclovir was significantly associated with the risk of absolute neutropenia (<1,500/mm(3)) compared with all therapies (Odds Ratio (OR) 3.63 95%CI 1.75 to 7.53; P = 0.001; I(2) = 0%); with ganciclovir only (OR 2.88, 95%CI 1.27 to 6.53; P = 0.01; I(2) = 0%); or with non-ganciclovir therapies (OR 8.30, 95%CI 1.51 to 45.58; P = 0.01; I(2) = 10%). For a neutropenia cut-off of <1,000/mm(3), the risk remained elevated (OR 1.97, 95%CI 1.03 to 3.67; P = 0.04; I(2) = 0%). For every 24 patients who receive valganciclovir prophylaxis, one more will develop neutropenia compared to other therapies. The risk of late-onset CMV disease with valganciclovir was similar to ganciclovir and higher than those with non-ganciclovir therapies (OR 8.95, 95%CI 1.07 to 74.83; P = 0.04; I(2) = 0%]. One more patient will develop late-onset CMV disease for every 25 who receive valganciclovir compared to treatment with non-ganciclovir therapies. The risk of CMV tissue-invasive disease in liver recipients receiving valganciclovir was 4.5 times the risk seen with ganciclovir [95%CI 1.00 to 20.14] (p = 0.04). All results remained consistent across different study designs, valganciclovir doses, and CMV serostatus.

CONCLUSIONS

Valganciclovir shows no superior efficacy and significantly higher risk of absolute neutropenia, CMV late-onset disease, and CMV tissue-invasive disease compared to other standard therapies. Due to the availability of efficacious, safer, and lower cost drugs (high-dose acyclovir, valacyclovir, ganciclovir), our results do not favor the use of valganciclovir as a first-line agent for CMV preemptive or universal prophylaxis in SOT patients.

Progress towards recombinant anti-infective antibodies

The global market for monoclonal antibody therapeutics reached a total of $11.2 billion in 2004, with an impressive 42% growth rate over the previous five years and is expected to reach approximately $34 billion by 2010. Coupled with this growth are stream-lined product development, production scale-up and regulatory approval processes for the highly conserved antibody structure. While only one of the 21 current FDA-approved antibodies, and one of the 38 products in advanced clinical trials target infectious diseases, there is increasing academic, government and commercial interest in this area. Synagis, an antibody neutralizing respiratory syncitial virus (RSV), garnered impressive sales of $1.1 billion in 2006 in spite of its high cost and undocumented effects on viral titres in human patients. The success of anti-RSV passive immunization has motivated the continued development of anti-infectives to treat a number of other infectious diseases, including those mediated by viruses, toxins and bacterial/ fungal cells. Concurrently, advances in antibody technology suggest that cocktails of several monoclonal antibodies with unique epitope specificity or single monoclonal antibodies with broad serotype specificity may be the most successful format. Recent patents and patent applications in these areas will be discussed as predictors of future anti-infective therapeutics.

Diagnostic value of HCMV pp65 antigen detection by FCA for symptomatic and asymptomatic infection: compared to quantification of HCMV DNA and detection of IgM antibody in infants

Human cytomegalovirus (HCMV) can cause symptomatic or asymptomatic infection in infants. One hundred and twenty-six infants were assessed clinically for disease in infantile period. Eighty of them were classified as symptomatic infection on the basis of physical, instrumental, and laboratory findings, 5 were demonstrated by following up to have later developed HCMV disease, and the other 41 infants were classified as asymptomatic infection. HCMV DNA was positive in all urine samples of the symptomatic infants detected by quantitative polymerase chain reaction. HCMV-IgM antibody detected by chemiluminescent immunoassay (CLIA) was positive in 62 of the 85 symptomatic infants, but was negative in all of the samples of asymptomatic infants. HCMV pp65 antigen detected by flow cytometry assay (FCA) was positive in 77 of the 85 symptomatic infants and in none of the asymptomatic infants. The coincidence to symptom of HCMV pp65 antigen detection was higher than those of HCMV DNA and HCMV-IgM antibody detection. The sensitivity, specificity, positive prognostic value and the negative prognostic value of HCMV pp65 antigen detection for diagnosis of HCMV infection was 90.6, 100, 100 and 83.7%, respectively. We concluded that detection of pp65 antigen by FCA is more sensitive for diagnosis of HCMV infection than detection of HCMV-IgM antibody and is better than HCMV DNA quantification for distinguishing the symptomatic and asymptomatic HCMV infection in infants.

Immunobiology of human cytomegalovirus: from bench to bedside

SUMMARY

Following primary infection, human cytomegalovirus (HCMV) establishes lifelong latency and periodically reactivates without causing symptoms in healthy individuals. In the absence of an adequate host-derived immune response, this fine balance of permitting viral reactivation without causing pathogenesis is disrupted, and HCMV can subsequently cause invasive disease and an array of damaging indirect immunological effects. Over the last decade, our knowledge of the immune response to HCMV infection in healthy virus carriers and diseased individuals has allowed us to translate these findings to develop better diagnostic tools and therapeutic strategies. The application of these emerging technologies in the clinical setting is likely to provide opportunities for better management of patients with HCMV-associated diseases.

Gastrointestinal cytomegalovirus infections in organ transplant patients

A cytomegalovirus (CMV) az immunszupprimált szervtranszplantált betegek egyik veszélyes fertőzése. A transzplantáltak 80-90%-ánál a fertőzés inaktív; a tünetekkel járó CMV-betegség gyakorisága 30-40%-os. Gastrointestinalis CMV-betegség a szervátültetettek mintegy 10%-ában fordul elő, a kórkép a tápcsatorna bármelyik szakaszát érintheti. A CMV-betegség leggyakrabban a nyálkahártya károsodásával, fekélyekkel, eróziókkal, vérzésekkel jár, oka lehet a tápcsatorna motilitási zavarának, ritkábban gastrointestinalis gyulladásos teriméknek, perforációknak. A diagnosztika alapja az endoszkópos vizsgálat biopsziás mintavétellel. A biopsziás minta szövettani vizsgálatakor keresni kell a CMV-fertőzésre jellemző cytomegaliás sejteket intranukleáris („bagolyszem”) és intracitoplazmatikus zárványokkal. A vírus kimutatására számos mikrobiológiai, immunhisztokémiai és molekuláris biológiai módszer létezik. Igazolt kórkép esetén a kezelés kettős: az elváltozásoknak, tüneteknek megfelelő gasztroenterológiai kezelés mellett meg kell kezdeni az antivirális terápiát általában intravénás ganciclovirrel és/vagy orális valganciclovirrel. Lényeges a betegség kialakulásának megelőzése is: a magas rizikójú betegcsoportban általános profilaxis javasolt per os valganciclovirrel, speciális esetekben hiperimmunglobulinnal; közepes kockázat esetén a mikrobiológiai surveillance eredménye alapján preemptív kezelés kezdhető.

Cytomegalovirus infection in ulcerative colitis: a prospective, comparative study on prevalence and diagnostic strategy

BACKGROUND

Cytomegalovirus (CMV) infection has been reported in ulcerative colitis (UC), especially in severe, steroid-refractory disease. However, its role in steroid-refractoriness remains unknown. Our goals were to evaluate the prevalence of CMV disease in UC, the best diagnostic strategy, and the influence of disease activity and/or treatment in its development.

METHODS

Prospective, observational study including 114 subjects with active UC requiring intravenous steroids, steroid-refractory UC, inactive UC on mesalamine, inactive UC on azathioprine, and healthy controls. CMV antibodies, pp65-antigenemia, and rectal biopsies for hematoxylin and eosin staining, immunohistochemistry, and CMV-pp67 mRNA were performed. These procedures were repeated after medical treatment only in patients with active UC. CMV disease was defined by the presence of inclusion bodies and/or positive immunohistochemistry in colonic biopsies.

RESULTS

CMV disease was found in 6 steroid-refractory, CMV-IgG-positive UC patients but not among controls, inactive UC, or steroid-responding UC patients. In 5 out of the 6 patients, CMV disease was diagnosed after 7-10 days on cyclosporine.

CONCLUSIONS

CMV disease in UC only affects seropositive, steroid-refractory UC patients. Steroid/cyclosporine treatment together with disease activity may predispose to latent colonic CMV reactivation. The impact of antiviral therapy on the clinical outcome of these patients remains to be elucidated.

CMV-hyperimmune globulin for preventing cytomegalovirus infection and disease in solid organ transplant recipients: a meta-analysis

OBJECTIVE

The goal of this meta-analysis was to investigate the impact of cytomegalovirus hyperimmune globulin (CMVIG) on cytomegalovirus (CMV) infection, CMV disease, and mid-term survival in solid organ transplant recipients.

METHODS

Medline, EMBASE, and the Cochrane databases were searched since their inceptions until 2006. Inclusion criteria comprised: prospective randomized trials, in solid organ transplantation which received CMV prophylaxis including CMVIG on one of the treatment arms. Random effects models were used to calculate pooled risk ratios (RR) and meta-regression was employed to explain study heterogeneity. Stratified analyses were conducted and Funnel plot was used to assess publication bias.

RESULTS

Literature searches identified 11 randomized trials (698 patients; median follow-up: 12 months, range: 3-22 months) including six randomized trials (302 patients) after kidney transplantation. The analysis demonstrated a beneficial effect of the prophylactic use of CMVIG on total survival [RR (95% confidence interval; CI): 0.67 (0.47-0.95)] and prevention of CMV-associated death [RR (95% CI): 0.45 (0.24-0.84)] in solid organ transplant recipients but not kidney transplant recipients [RR (95% CI): 0.35 (0.12-1.04)]. CMV disease was significantly reduced in all recipients receiving prophylactic CMVIG [RR (95% CI): 0.697 (0.57-0.85)]. CMVIG had no impact on CMV-infections and clinically relevant rejections.

CONCLUSIONS

Prophylactic administration of CMVIG after solid organ transplantation is associated with improved total survival, reduced CMV disease, and CMV-associated deaths.

A lower incidence of cytomegalovirus infection in de novo heart transplant recipients randomized to everolimus

BACKGROUND

Cytomegalovirus (CMV) infection in recipients of cardiac transplants is associated with higher rates of morbidity. A recent phase III trial showed highly significantly (P<0.001) lower CMV rates with the proliferation signal inhibitor everolimus compared to azathioprine (AZA). To better define this association, data on CMV risk factors were collected retrospectively and analyzed.

METHODS

Data on CMV risk factors from a multicenter phase III trial on de novo heart transplant recipients (n=634) receiving a triple immunosuppressive regimen randomized to everolimus 1.5 mg/day (group 1), everolimus 3 mg/day (group 2), or AZA (group 3) were merged with prospectively collected CMV-related outcome data and analyzed.

RESULTS

CMV-positive donors (D+) and CMV-negative recipients (R-) were evenly distributed across groups 1-3 at 36/209 (17.2%), 48/211 (22.7%), and 38/214 (17.8%), respectively. CMV prophylaxis had been given for a mean (SD) of 175 (127.8), 183 (137.1), and 177 (132.9) days, respectively. In the high-risk D+/R- subgroup with prophylaxis, the proportions of patients with CMV infection compared with group 3 (12/29 [41.4%]) were 3/25 (12.0%) in group 1 (P=0.031) and 6/36 (16.7%) in group 2 (P=0.049). In D+/R+ subgroups either with or without prophylaxis, the everolimus groups had less CMV disease (P<0.001). The incidence of CMV syndrome, organ involvement, and laboratory evidence was lower with everolimus use compared to AZA.

CONCLUSIONS

Everolimus is associated with lower rates of CMV infection, syndrome, or organ involvement, suggesting an additional advantage from the use of everolimus in cardiac transplant recipients.

Relationship between pp65 antigenemia levels and real-time quantitative DNA PCR for Human Cytomegalovirus (HCMV) management in immunocompromised patients

Background

Quantitative real-time PCR assays, which are more rapid and practical than pp65 antigenemia determination, are progressively becoming the preferred method for monitoring Human Cytomegalovirus (HCMV) reactivation. However, the relationship between HCMV DNA and antigenemia levels is still under investigation. The aim of this study was to analyse the relationship between HCMV DNA and pp65 antigenemia levels in order to identify clinically useful threshold values for the management of patients.

Methods

475 consecutive samples from 156 immunosuppressed patients were tested for HCMV by pp65 antigenemia and Real-time PCR assay.

Results

136 out of 475 consecutive samples derived from 48 patients showed evidence of HCMV infection. HCMV DNA was detected in 106 samples, pp65 antigen in 3, and both markers in 27. pp65 antigen detection was associated with higher HCMV DNA levels. The cut-off HCMV DNA level that best predicted pp65 antigenemia in this series of samples was 11,500 copies/ml, but different threshold levels could be observed for specific groups of patients. HCMV disease was observed in 5 out of 48 patients with active HCMV infection. The presence of clinical symptoms was associated with positive pp65 and with higher antigenemia levels. Higher HCMV DNA load at the onset of viral replication was correlated to the development of clinical symptoms.

Conclusion

Both pp65 antigenemia and HCMV DNA load can be useful for the prospective monitoring of immunocompromised subjects. Specific cut-off levels capable of triggering preemptive antiviral treatment should be determined in accordance to the type of test used and the characteristics of patients and prospectively validated.

Resistance to combined ganciclovir and foscarnet therapy in a liver transplant recipient with possible dual-strain cytomegalovirus coinfection

We present a case report of a cytomegalovirus (CMV)-seronegative, 58-year-old male who received a CMV-seropositive donor liver transplant without CMV prophylaxis. On postoperative day 30, the patient developed primary CMV disease that responded to ganciclovir. On postoperative day 114, however, he was diagnosed with recurrent CMV infection. Despite aggressive, combined antiviral treatment with ganciclovir and foscarnet and reduction of immunosuppression, viral clearance was never achieved. Serum samples were collected throughout the infectious process for viral DNA analysis. Portions of the UL97 and UL54 genes were amplified and compared to the AD169 wild-type strain. Sequencing studies revealed the presence of mutations in viral isolates obtained after clinical resistance was observed. These mutations were not present in samples obtained during the primary CMV infection. Our findings suggest the presence of coinfection with at least 2 different strains of CMV rather than induction of mutations after ganciclovir therapy.

Cutaneous manifestations of cytomegalovirus disease in renal transplant recipients: a case series

Cytomegalovirus (CMV) is an important and well-described opportunistic virus in the immunocompromised host, with infection occurring mainly after the first month in the new renal transplant recipient. CMV can present as primary infection, reinfection, or reactivation of latent disease. It is capable of protean manifestations. Cutaneous manifestations are variable, rare, and diagnosis often delayed. We present 3 cases of cutaneous CMV disease in renal transplant recipients. Manifestations in our patients included ulceration of the tongue and perianal areas, facial petechiae, and nodular lesion involving the ear. This case series serves to highlight the importance of early skin biopsy in the diagnosis and management of cutaneous CMV disease.

Analysis of cytomegalovirus (CMV) viremia using the pp65 antigenemia assay, the amplicor CMV test, and a semi-quantitative polymerase chain reaction test after allogeneic marrow transplantation

A pp65 antigenemia assay for polymorphonuclear leukocytes (PMNLs) (CINAkit Rapid Antigenemia), and a qualitative polymerase chain reaction (PCR) test for plasma 'PCR-P qual' (Amplicor cytomegalovirus [CMV] test) were performed for 126 samples (blood and plasma) obtained from 18 bone marrow transplant patients, over a 9-month surveillance period. Among those samples, 92 were assayed with a semi-quantitative PCR test for PMNLs 'PCR-L quant.' The number of samples with a positive CMV test for antigenemia and PCR-P qual assays was 20.63% and 12.7%, respectively, whereas the PCR-L quant assay was positive in 48 of the 92 samples assayed (52.17%). The rates of concordance of the results of PCR-P qual and antigenemia, PCR-P qual and PCR-L quant, antigenemia and PCR-L quant were 92%, 65.2% and 66.8%, respectively. The analysis of the results for the 92 specimens tested by all 3 methods showed a rate of concordance of 63% among all methods. Good agreement (kappa=0.72) was found only between pp65 Ag and PCR-P qual assays. Clinical disease correlates with an antigenemia high viral load. Three patients had CMV disease despite preemptive therapy, and all of them had graft-versus-host-disease (GVHD). PMNLs-based assays are more efficient in monitoring CMV reactivation, but for high-risk patients with GVHD, more sensitive assays (real-time PCR) must be done.

Efficacy and safety of preemptive anti-CMV therapy with valganciclovir after kidney transplantation

BACKGROUND

CMV infections still pose a potentially serious threat to kidney transplant recipients and have a significant impact on graft as well as patient survival. The antiviral agent valganciclovir (VGCV) has a greater bioavailability after oral administration than oral ganciclovir (GCV) and can be considered a substitute for GCV. The substance is approved in North America and Europe for anti-CMV prophylaxis after organ transplantation. In this pilot study, we examined if VGCV could also be administered in preemptive treatment of CMV infections.

METHODS

Twenty-eight renal transplant recipients suffering from 32 asymptomatic episodes of CMV infection were treated with VGCV and followed up. CMV infection was diagnosed by routine controls of pp65-antigenemia in pre-defined intervals. All patients received sequential quadruple immunosuppression. VGCV was given for up to 12 wk in a dosage adapted to renal graft function. Efficacy and safety parameters were monitored for 16 wk.

RESULTS

Twenty-seven episodes of CMV antigenemia, two patients progressing to CMV syndrome and three patients progressing to CMV disease were treated. Primary efficiency was 79%, Four patients relapsed and were treated with a second course resulting in serological recovery. Two patients did not respond to oral VCGV and were switched to another antiviral agent. Graft function remained stable during and after treatment. Serious side effects were seen in seven patients, four patients complained of diarrhea and gastrointestinal pain, three patients suffered from leucopenia, in one of these treatment had to be temporary paused. Fifty-nine percent of all episodes were treated in a completely ambulatory setting.

CONCLUSIONS

VGCV can be considered as an option also for preemptive treatment of CMV infections after renal transplantation. The antiviral potency seems to be adequate, potential side effects are comparable with IV GCV. Because of the improved pharmacokinetics of VGCV the substance can be used to abbreviate or even completely avoid in-hospital care of CMV infections.

Transfusion-transmitted cytomegalovirus (CMV) infections in a murine model: characterization of CMV-infected donor mice

BACKGROUND

Donor and recipient mechanisms that modulate the incidence and severity of transfusion-transmitted cytomegalovirus (TT-CMV) are unclear. The kinetics of murine CMV (MCMV) infection in the peripheral blood of donor mice were investigated to determine the utility of this model for studying TT-CMV.

STUDY DESIGN AND METHODS

BALB/cByJ mice, experimentally infected with Smith strain MCMV, were killed at serial time points up to 28 days after infection. Peritoneal exudate cells (PECs), peripheral blood white blood cells (WBCs), plasma, and marrow were tested for MCMV DNA with quantitative polymerase chain reaction (PCR), replication-competent virus with quantitative culture, and transcription of viral genes with reverse transcription (RT)-PCR targeted at the immediate-early 1 (ie1) gene.

RESULTS

PECs, macrophages infected by MCMV shortly after intraperitoneal inoculation, demonstrated high mean levels of MCMV DNA (10(5)-10(7) genome equivalents [geqs]/10(5) PECs), virus production (10(1)-10(4) infectious virions/10(5) PECs), and ie1 gene transcription, demonstrating productive infection. In contrast, while MCMV loads averaged 10(4) to 10(6) geqs per 10(5) peripheral WBCs, all WBC samples were uniformly negative for MCMV ie1 expression by RT-PCR and for culturable virus, consistent with latent MCMV infection. Plasma and marrow showed lower viral loads than WBCs and PECs and were all negative by culture and RT-PCR analysis.

CONCLUSIONS

Following experimental MCMV infection, murine peripheral blood WBCs appear to be latently infected with virus (MCMV DNA-positive; MCMV RNA-negative; MCMV culture-negative), similar to the latently infected human monocytes in peripheral blood of CMV-seropositive donors. These donor kinetics suggest that the experimental MCMV system can be used to effectively model the mechanisms of TT-CMV infections in humans.

Severe graft rejection, increased immunosuppression, and active CMV infection in renal transplantation

Associations between active cytomegalovirus (CMV) infection, graft rejection, rejection therapy, and clinical signs and symptoms have been shown repeatedly. However, the causes and the sequence of events remain an area of debate. Two hundred twenty five patients with cadaveric renal transplant were included in the present study. Clinical signs and symptoms, and the development of active CMV infections were recorded during the first 3 months after renal transplantation. CMV monitoring by pp65-antigenemia was performed followed by preemptive antiviral therapy. Delayed graft function and severe graft rejection followed by anti T-cell antibody therapy was associated with the development of active CMV infection. In contrast, the induction therapy with anti-T-cell antibodies was not associated with more active CMV infections. Post-transplant morbidity determined by fever, pneumonia, and duration of hospital stay was increased significantly in patients with active CMV infection. However, in times of preemptive antiviral therapy an increased morbidity occurred in association with severe graft rejection and not with active CMV infection alone. In patients with renal transplantation and preemptive antiviral therapy, the morbidity was no more influenced by the CMV serostatus although the prevalence of active CMV infection was obviously different between CMV exposed (D+/R+,D+/R-, D-/R+) and unexposed (D-/R-) patients. Severe graft rejection and increased immunosuppression could stimulate cooperatively active CMV infections whereas immunosuppression alone may not be as effective. Prevention of severe graft rejection may be important to decrease early post-transplant morbidity and also the development of active CMV infections after renal transplantation.

Evaluation of three polymerase chain reaction tests targeting morphological transforming region II, UL-83 gene and glycoprotein O gene for the detection of human cytomegalovirus genome in clinical specimens of immunocompromised patients in Chennai, India

Background

Human Cytomegalovirus (HCMV) continues to be an important cause of morbidity and occasional mortality in immunocompromised patients. Polymerase chain reaction (PCR) is the most sensitive and commonly used method for the assessment of HCMV infection in the immunocompromised patients at risk from severe associated clinical manifestations. However, there is little consistency in the qualitative PCR used for different regions of HCMV genome. Therefore, the performance of three Qualitative PCR tests to detect HCMV genome in clinical specimens from immunocompromised patients was evaluated. With pp65 antigenemia assay as the "gold standard", nested PCR for morphological transforming region II (mtr II) and glycoprotein O (gO) gene and uniplex PCR for UL 83 gene were applied on 92 consecutive clinical specimens obtained from 74 immunocompromised patients with clinically suspected HCMV disease. Virus isolation was attempted on 12 clinical specimens from six pp65 antigenemia positive patients. Based on the pp 65 antigenemia results as "gold standard", the sensitivity, specificity, positive predictive value and negative predictive value for each PCR was calculated.

Results

The PCR targeting mtr II region showed a higher sensitivity (100%) and negative predictive value (100%) than the other two PCRs in detecting HCMV DNA from clinical specimens obtained from different immunocompromised patient population of Chennai region, India.

Conclusion

The results suggests that the optimal method of detection of HCMV DNA could be achieved by PCR using primer sequences targeting mtr II region of genome of HCMV in Chennai region, India.

Human cytomegalovirus UL27 is not required for viral replication in human tissue implanted in SCID mice

Inhibition of the human cytomegalovirus UL97 kinase by maribavir is thought to be responsible for the antiviral activity of this compound. Some mutations that confer resistance to maribavir map to UL97, however additional mutations that also confer resistance to the drug were mapped to UL27. These open reading frames share a low level of homology, yet the function of pUL27 remains unknown. A recombinant virus with a deletion in the UL27 open reading frame was reported previously to exhibit a slight replication deficit, but a more important function in vivo was hypothesized given its homology to the UL97 kinase. The potential for an important function in vivo was investigated by determining if these knockout viruses could replicate in human tissue implanted in SCID mice. None of the AD169 derived viruses replicated well in the implanted thymus/liver tissue, and is consistent with previous observations, although all of the viruses replicated to some degree in retinal tissue implants. Replication of the parent viruses was observed at 7 days post inoculation, whereas no replication was detected with any of the recombinant viruses with deletions in UL27. By day 14, replication was detected in two of the three knockout viruses and in all of the viruses by day 42. These data are consistent with minimal defects observed in cell culture, but are not consistent with an important role for UL27 in vivo. We conclude that UL27 is not required for viral replication in vivo.

New reporter cell line to evaluate the sequential emergence of multiple human cytomegalovirus mutations during in vitro drug exposure

We developed a new reporter cell line for human cytomegalovirus (HCMV) drug susceptibility testing. This cell line was obtained by incorporating the luciferase reporter gene under the control of an HCMV-specific promoter into the genome of astrocytoma cells (U373MG). We then used our reporter cell line to evaluate phenotypic changes conferred by the sequential emergence of HCMV UL54 and UL97 mutations following long-term drug exposure. The laboratory strain AD169 was passaged in the presence of increasing concentrations of ganciclovir (one viral line) or foscarnet (two viral lines). Resistant viruses were plaque purified at five different concentrations of ganciclovir and at three different concentrations of foscarnet. In addition to the previously described M460I and L595S UL97 mutations and the L545S and V812L UL54 mutations, exposition to ganciclovir (up to 3,000 microM) resulted in the selection of two unreported UL54 mutations (P829S and D879G). Passages in the presence of foscarnet (up to 3,000 microM) resulted in the selection of seven not previously described UL54 mutations (K500N, T552N, S585A, N757K, L802V, L926V, and L957F) in addition to the N408D mutation that has been associated with ganciclovir and cidofovir resistance. Long-term exposure of HCMV to either ganciclovir or foscarnet ultimately resulted in the selection of multiple UL54 mutations that conferred high levels of resistance to all approved HCMV DNA polymerase inhibitors, i.e., ganciclovir, cidofovir, and foscarnet. Emergence of each viral mutation conferred stepwise increases in drug 50% inhibitory concentrations that could be objectively measured with the new reporter cell assay.

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

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

Comparative activities of lipid esters of cidofovir and cyclic cidofovir against replication of herpesviruses in vitro

Cidofovir (CDV) is an effective therapy for certain human cytomegalovirus (HCMV) infections in immunocompromised patients that are resistant to other antiviral drugs, but the compound is not active orally. To improve oral bioavailability, a series of lipid analogs of CDV and cyclic CDV (cCDV), including hexadecyloxypropyl-CDV and -cCDV and octadecyloxyethyl-CDV and -cCDV, were synthesized and found to have multiple-log-unit enhanced activity against HCMV in vitro. On the basis of the activity observed with these analogs, additional lipid esters were synthesized and evaluated for their activity against herpes simplex virus (HSV) types 1 and 2, human cytomegalovirus, murine cytomegalovirus, varicella-zoster virus (VZV), Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), and HHV-8. Using several different in vitro assays, concentrations of drug as low as 0.001 microM reduced herpesvirus replication by 50% (EC50) with the CDV analogs, whereas the cCDV compounds were generally less active. In most of the assays performed, the EC50 values of the lipid esters were at least 100-fold lower than the EC50 values for unmodified CDV or cCDV. The lipid analogs were also active against isolates that were resistant to CDV, ganciclovir, or foscarnet. These results indicate that the lipid ester analogs are considerably more active than CDV itself against HSV, VZV, CMV, EBV, HHV-6, and HHV-8 in vitro, suggesting that they may have potential for the treatment of infections caused by a variety of herpesviruses.

A comparative randomised study of valacyclovir vs. oral ganciclovir for cytomegalovirus prophylaxis in renal transplant recipients

An open, prospective, randomised study was conducted to compare the safety and efficacy of valacyclovir vs. oral ganciclovir for cytomegalovirus (CMV) prophylaxis in renal transplant recipients. Eighty-three renal transplant recipients were assigned randomly to receive valacyclovir (n=43) or oral ganciclovir (n=40) for the first 3 months after transplantation. Both groups were similar in terms of demographics, primary renal disease, graft source, HLA matching, immunosuppressive therapy and donor-recipient CMV antibody status. CMV infection was diagnosed by detection of virus DNA in plasma with the Amplicor CMV Test. CMV disease was observed in only one patient belonging to the ganciclovir group, who developed enterocolitis 6 months post-transplantation. No difference was observed between the two treatment groups with respect to detection of CMV DNA, virus infections other than CMV, acute rejection episodes, and serum creatinine levels at 3 and 6 months following transplantation. An increased number of bacterial infections was noted in the ganciclovir group (p 0.003). No adverse reactions with either treatment were reported. The estimated cost of valacyclovir treatment was 20% higher than that of ganciclovir treatment. Overall, both valacyclovir and oral ganciclovir were found to be effective and safe for CMV prophylaxis in renal transplant recipients. Decisions regarding prophylactic regimens should include additional criteria, such as cost or possible development of resistance.

Pharmacodynamics of oral ganciclovir and valganciclovir in solid organ transplant recipients

BACKGROUND

A randomized, double-blind study was conducted to evaluate the pharmacokinetics of ganciclovir following oral administration of ganciclovir or valganciclovir for prophylaxis of cytomegalovirus (CMV) disease in solid organ transplant recipients (n = 240/372).

METHODS

The correlations between individual exposure to ganciclovir during prophylaxis, with CMV viremia incidence during and after treatment, CMV disease up to 12 months posttransplant, and hematological toxicity were assessed.

RESULTS

Mean daily areas under the curve (AUCs) of ganciclovir from valganciclovir and oral ganciclovir were 46.3 +/- 15.2 and 28.0 +/- 10.9 microg.h/ml (mean +/- SD), respectively. Viremia was suppressed during prophylaxis when exposure to ganciclovir was 40-50 microg.h/ml, AUCs typical of those achieved in valganciclovir-treated patients. The development of viremia 1 month after ending prophylaxis was also reduced with higher ganciclovir AUC (median predicted incidence, 20% and 10% at AUCs of 33 and 50 microg h/ml, respectively). The development of CMV disease within 1 year of transplant was 17.6% and independent of prophylactic exposure to ganciclovir. There was only a weak tendency to increased neutropenia and leukopenia with higher ganciclovir exposure.

CONCLUSIONS

The greater systemic exposure to ganciclovir delivered by valganciclovir was associated with delayed development of viremia. There was only a weak association between AUC and hematological toxicity.

Transfusion of leukoreduced cellular blood components from cytomegalovirus-unscreened donors in allogeneic hematopoietic transplant recipients: analysis of 72 recipients

Leukoreduction of blood components has been considered a safe alternative to screening donors for CMV. The objective of this study is to analyze the effectiveness of bedside leukoreduction in preventing CMV transmission. We retrospectively studied 72 transplant recipients and donors who were CMV-seronegative pairs. All patients were transfused with CMV-unscreened cellular blood products leukoreduced at the bedside using leukoreduction filters. Quality control measures performed monthly in our leukoreduced blood components consistently demonstrated that at least 95% of the units sampled meet the leukoreduction criterion established by the American Association of Blood Banks standards. The CMV status of the recipients and donors was determined before transplantation by the latex agglutination assay. Recipients were observed for at least 100 days after transplantation. CMV cultures of urine, buffy coat, bone marrow, and bronchial washings were done weekly when indicated. CMV antigenemia testing was performed twice weekly: 11 transplant recipients seroconverted after transplantation. One patient was positive for CMV antigenemia 4 months after transplantation, but did not have CMV infection. Two of 61 patients who were not seroconverted were CMV antigenemia positive and did not have CMV infection: leukoreduction of cellular blood products is an efficient method of preventing CMV infection.

Strategies for the prevention of cytomegalovirus infection and disease in pediatric liver transplantation recipients

Cytomegalovirus (CMV) is the most common opportunistic infection following solid organ transplantation. Prevention and management of CMV infection has assumed a higher priority as transplantation has become a frequent treatment for many congenital and acquired disorders, as more potent immunosuppressive agents have become available, new molecular and virologic assays to detect CMV have made their way from research to clinical laboratories and new antiviral medications and biologics have been developed. Management strategies are diverse; however, there are little or no data from large controlled pediatric trials demonstrating the superiority of any particular approach. This review outlines the current strategies employed to prevent CMV infection and disease and summarizes the strengths and limitations of each regimen to guide clinicians in the selection of the optimal preventative approach.

Risk Factors for Cytomegalovirus Viremia and Disease Developing after Prophylaxis in High-Risk Solid-Organ Transplant Recipients

BACKGROUND

Cytomegalovirus (CMV) D+/R- solid-organ transplant (SOT) recipients carry increased risk of developing CMV disease; however, other risk factors in these patients have not been delineated.

METHODS

We examined 20 demographic and clinical variables for their association with the development of CMV disease, as defined by an independent endpoint committee (IEC) and also by the investigator (investigator treated [IT]), or CMV viremia within 12 months of transplant in D+/R- transplant recipients who received prophylaxis with valganciclovir or oral ganciclovir for 100 days.

RESULTS

Recipients with low creatinine clearance (Ccr,<40 mL/min) at screening had a significantly increased hazard of developing IEC-defined CMV disease (hazards ratio [HR]=4.28, confidence interval [CI] 1.69, 10.83). Females were twice as likely (HR=2.19, CI .21, 3.99) to develop IEC-defined CMV disease than males. These variables were associated with an increased risk of IEC-defined CMV disease in time-dependent models. Recipients with blood group A were also more likely to develop IEC-defined CMV disease than those with group O (HR=2.36 CI 1.24, 4.51) in the logistic regression model only. Prophylactic drug, organ type, recipient age, rejection episodes, and maintenance immunosuppression regimen were not associated with IEC-defined CMV disease. Female sex was the only variable associated with the development of CMV viremia (odds ratio [OR]=1.65; CI 1.03, 2.65) and IT CMV disease (OR=1.78; CI 1.08, 2.93).

CONCLUSIONS

Low Ccr at screening and blood type A are risk factors for IEC-defined CMV disease, and female sex was a risk factor for IEC- and IT-defined CMV disease and viremia in high-risk SOT recipients. These variables should perhaps be considered when optimizing treatment.

Canadian consensus guidelines for the management of cytomegalovirus disease in HIV/AIDS

BACKGROUND

The management of HIV-infected patients with cytomegalovirus (CMV) disease has changed significantly with the availability of highly active antiretroviral therapy (HAART).

OBJECTIVES

These updated guidelines are intended to provide practical help to physicians managing HIV-positive patients with or at risk for CMV disease.

METHODS

The 10 members of the Canadian CMV Disease in HIV/AIDS Consensus Group were infectious disease specialists, a primary care physician and ophthalmologists with expertise in HIV and CMV infection. Financial support by Hoffmann-La Roche Canada Ltd was unrestricted, and was limited to travel expenses and honoraria. The consensus group met in June and October 2002. Key areas to be considered were identified, and group members selected, reviewed and presented relevant recent literature for their assigned section for the group's consideration. Evidence was assessed based on established criteria, which were expert opinions of the members. Draft documents were circulated to the entire group and modified until consensus was reached. The final guidelines represent the group's consensus agreement. The guidelines were approved by the Canadian Infectious Disease Society.

RESULTS AND CONCLUSIONS

The guidelines address symptom monitoring, screening for early detection and prevention, and treatment using oral, intravenous and intraocular anti-CMV therapies in conjunction with HAART.

Infection with cytomegalovirus in patients with inflammatory bowel disease: prevalence, clinical significance and outcome

Despite frequent use of immunosuppressive drugs in patients with inflammatory bowel disease (IBD) and reports of cytomegalovirus (CMV) infection following post-transplant immunosuppression, data on the frequency and clinical significance of CMV in patients with IBD are scant. Sixty-three patients with IBD (61 ulcerative colitis and two Crohn's disease) were evaluated for CMV using serology (IgM antibody, μ-capture ELISA), PCR for CMV DNA in colonic biopsy and histological assessment of haematoxylin and eosin-stained colonic biopsy. Positive result in any test was considered as CMV infection. Various parameters associated with CMV infection were analysed using univariate and multivariate analysis. Ten of 63 (15.8 %) patients (age 36.0 ± 11.2 years, 31 female) were infected with CMV (DNA alone in four, IgM antibody alone in two and both in four, inclusion body in one). Patients with CMV infection were more often female (8/10 vs 23/53,P< 0.05), had pancolitis (10/10 vs 33/53,P< 0.05), histological activity (9/10 vs 17/53,P< 0.005) and used azathioprine (5/10 vs 7/53,P= 0.04; Fisher exact test for all). On multivariate analysis, female gender, pancolitis and histological activity were the independent factors associated with infection. Patients with CMV infection more often required surgical treatment for IBD (4/10 vs 4/53,P= 0.01) and had fatal outcome (3/10 vs 0/53,P= 0.003). CMV infection in patients with IBD may be common and is associated with poor outcome. PCR of rectal biopsy was the most sensitive method of detection followed by IgM antibody for diagnosis.

Reduced expression of gamma interferon in serum and marked lymphoid depletion induced by Porphyromonas gingivalis increase murine morbidity and mortality due to cytomegalovirus infection

Porphyromonas gingivalis, a gram-negative anaerobe, is a major etiological agent of severe forms of periodontal disease. Although periodontal disease is considered a localized disease, accumulating evidence indicates that it may lead to a predisposition to a decline in immunocompetence. Human cytomegalovirus (CMV) commonly infects all human populations without producing significant clinical symptoms. Immunocompromised patients usually develop a primary or reactivated CMV infection, which is associated with high rates of morbidity and mortality. The aim of this study was to determine whether P. gingivalis increases animal susceptibility to CMV infection. Mice were inoculated with CMV and infected locally with P. gingivalis 3 days after the virus inoculation. Mortality rates were monitored, and traces of viral DNA and bacterial infection were detected systemically by using real-time PCR. Local and systemic cytokine secretion was measured, and histological sections were used to assess the pathological state of infected organs. P. gingivalis- and CMV-coinfected mice showed dramatically higher mortality rates than mice infected with P. gingivalis or CMV only. Although the organs of coinfected mice exhibited decreased viral titers, distinct necrosis and tissue damage were more evident in the livers and spleens of these mice than in those of mice infected with CMV only. Furthermore, systemic gamma interferon levels were decreased in coinfected mice, and marked lymphoid depletion was observed in their necrotic organs. In parallel control Escherichia coli-CMV coinfection experiments, the mortality and pathological results were the same as those found in mice infected with CMV only. Our results suggest a specific influence of P. gingivalis on the mouse immune response, causing increased susceptibility to CMV infection.

Mechanism of action of the ribopyranoside benzimidazole GW275175X against human cytomegalovirus

New human cytomegalovirus (HCMV) therapies with novel mechanisms of action are needed to treat drug-resistant HCMV that arises during therapy with currently approved agents. 2-Bromo-5,6-dichloro-1-beta-D-ribofuranosyl-1H-benzimidazole (BDCRB) is an effective anti-HCMV agent with a novel mechanism of action, but problems with in vivo stability preclude clinical development. A D-ribopyranosyl derivative of BDCRB, GW275175X, displays similar antiviral activity without the in vivo stability problems. We present an initial description of the activity of GW275175X against HCMV, other herpesviruses, and selected nonherpesviruses. In addition, we show that it acts as a DNA maturation inhibitor like the parent compound, BDCRB, rather than via the mechanisms of action of 1263W94 or any anti-HCMV drugs approved for marketing. GW275175X is a promising candidate for clinical development as an anti-HCMV agent.

Comparison of combined prophylaxis of cytomegalovirus hyperimmune globulin plus ganciclovir versus cytomegalovirus hyperimmune globulin alone in high-risk heart transplant recipients1

BACKGROUND

Seronegative heart transplant recipients who receive an allograft from seropositive donors have a higher risk of developing cytomegalovirus (CMV) disease and cardiac allograft vasculopathy (CAV) and dysfunction. Neither CMV-specific hyperimmune globulin nor ganciclovir as sole CMV prophylaxis is sufficient to prevent CMV disease in high-risk patients. We retrospectively evaluated the efficacy of CMV-hyperimmune globulin with and without ganciclovir in 207 D+/R- heart transplant recipients.

METHODS

The study population was divided into two groups: Group A was composed of 96 patients who received CMV hyperimmune globulin as sole CMV prophylaxis, and group B was composed of 111 patients who received combined CMV prophylaxis. All recipients were subjected to quadruple cytolytic immunosuppression. Primary and secondary end points included prevention of CMV-associated death, CMV disease and productive infection, CAV, and overall infection.

RESULTS

There was no difference in overall survival between the two groups. Four patients in the group A died of CMV sepsis, whereas no CMV-associated death was observed in group B (P =0.0326). The actuarial incidence of CMV disease was significantly lower in patients who received double CMV prophylaxis (32.29 vs. 11.71, P =0.0003). Although no difference was observed with regard to productive CMV infection (53.12 vs. 65.77, P =not significant), CAV and overall infection rates were significantly higher in the first group (7.29 vs. 0.9, P =0.0157 and 70.83 vs. 62.16, P =0.03, respectively).

CONCLUSIONS

Double CMV prophylaxis consisting of CMV hyperimmune globulin and ganciclovir is able to abolish CMV death and prevent CMV disease in high-risk heart transplant recipients. Therefore, the use of a combination regimen is recommended for seronegative recipients with seropositive donors.

Resistance of human cytomegalovirus to the benzimidazole L-ribonucleoside maribavir maps to UL27

1-(beta-D-Ribofuranosyl)-2,5,6-trichlorobenzimidazole (TCRB) and its 2-bromo analog, BDCRB, are potent and selective inhibitors of human cytomegalovirus (HCMV) DNA processing and packaging. Since they are readily metabolized in vivo, analogs were synthesized to improve biostability. One of these, 1-(beta-L-ribofuranosyl)-2-isopropylamino-5,6-dichlorobenzimidazole (1263W94; maribavir), inhibits viral DNA synthesis and nuclear egress. Resistance to maribavir was mapped to UL97, and this viral kinase was shown to be a direct target of maribavir. In the present study, an HCMV strain resistant to TCRB and BDCRB was passaged in increasing concentrations of maribavir, and resistant virus was isolated. This strain (G2) grew at the same rate as the wild-type virus and was resistant to both BDCRB and maribavir. Resistance to BDCRB was expected, because the parent strain from which G2 was isolated was resistant due to known mutations in UL56 and UL89. However, no mutations were found in UL97 or other relevant open reading frames that could explain resistance to maribavir. Because sequencing of selected HCMV genes did not identify the resistance mutation, a cosmid library was made from G2, and a series of recombinant G2 wild-type viruses were constructed. Testing the recombinants for sensitivity to maribavir narrowed the locus of resistance to genes UL26 to UL32. Sequencing identified a single coding mutation in ORF UL27 (Leu335Pro) as the one responsible for resistance to maribavir. These results establish that UL27 is either directly or indirectly involved in the mechanism of action of maribavir. They also suggest that UL27 could play a role in HCMV DNA synthesis or egress of HCMV particles from the nucleus.

Cytomegalovirus infection in solid organ transplantation: economic implications

Cytomegalovirus (CMV) is a pathogen, commonly encountered in the recipients of solid organ transplantation and is an important cause of morbidity and mortality in these patients. CMV infection and disease have been shown to increase the cost of care in transplant recipients and several different strategies of prevention have been shown to be effective in clinical trials. A systematic review of published information on the economic impact of CMV in solid organ transplantation was performed; both clinical- and decision-analysis-based studies were reviewed. Clinical studies have shown that CMV infection and disease is associated with increased length of hospital stay and overall costs. Decision-analysis-based studies suggest that in general, antiviral chemoprophylaxis against CMV in transplant recipients is a cost-effective intervention compared with other established healthcare interventions such as strategies for colorectal cancer screening. Prophylaxis with oral or parenteral ganciclovir is probably the most cost-effective strategy; however, restricting prophylaxis to high-risk groups (such as donor seropositive/recipient seronegative status and the use of an antilymphocyte antibody) or chemoprophylaxis for an extended period does not improve cost effectiveness. Pre-emptive therapy is an evolving strategy for prevention of CMV disease in transplant recipients and is rapidly gaining in popularity. Well-designed trials incorporating prospective cost data and comparing pre-emptive therapy versus conventional antiviral prophylaxis are needed to establish the superiority of one strategy over the other.

Human cytomegalovirus DNA in plasma and serum specimens of renal transplant recipients is highly fragmented

Quantitation of cytomegalovirus (CMV) DNA in plasma and serum by PCR is increasingly used to identify patients at risk for developing CMV disease and to monitor the efficacy of antiviral therapy. Although CMV DNA levels are generally interpreted as viral loads, the exact nature of the viral DNA in these specimens is unknown. We studied the state of CMV DNA in plasma and serum specimens obtained from three renal transplant recipients at peak viral DNA levels during primary CMV infection. For this purpose, DNA isolated from these specimens was fractionated by size, and CMV DNA levels in the resulting DNA fractions were measured by quantitative PCR targeted at large (578-bp) and small (134-bp) amplicons. These experiments showed that the molecular sizes of DNA fragments from which CMV DNA is amplified were small (<2,000 bp), indicating that CMV DNA in plasma and serum is highly fragmented. Furthermore, CMV DNA levels were consistently higher when targeted at the smaller amplicon, providing additional evidence for the fragmentation of viral DNA. In conclusion, the first results with three patients have shown that CMV DNA in plasma and serum is highly fragmented and does not necessarily reflect the amount of infectious virus. These observations have potential consequences for understanding CMV pathogenesis and interpreting CMV DNA levels in individual patient management.

Preemptive strategy for ganciclovir administration against cytomegalovirus in liver transplantation recipients

In utilizing a preemptive strategy to minimize the occurrence of symptomatic cytomegalovirus (CMV) infection following liver transplant, only patients with proven CMV activity by direct detection are treated. We applied the following preemptive strategy for CMV infection to 49 sequential liver transplant recipients between 1998 and 2001. Patients were monitored for CMV activity using CMV p65 antigen assay for the first 10 months of the study. Thereafter, we changed the detection method to a quantitative PCR for plasma CMV-DNA. All patients were monitored post transplant, weekly for the first 3 months and then monthly. Only patients with detected CMV activity were treated with ganciclovir. Patients were divided into four groups, based on donor (D) and recipient (R) CMV status. In seven out of 49 patients (14.3%) CMV activity was detected: four in group D+/R-, and three in group D-/R-. Five out of these seven patients had asymptomatic CMV infection. Symptomatic CMV infection developed only in two of these seven patients, to give total rate of 4.1% (2/49). All seven patients developed CMV IgG antibody. 'Transient' CMV replication detected by PCR in five patients in group D+/R+ was not defined as infection. No patients developed organ-invasive CMV disease. The cost of anti-CMV treatment using the preemptive strategy was $1000/patient/1st year. Using preemptive strategy, early detection of CMV infection was achieved, allowing timely treatment. The use of ganciclovir for CMV infection in only 4.3% of the patients should have a positive impact on minimizing the risk of ganciclovir-resistant virus, and should reduce the cost of CMV prevention strategies.

Improved monitoring of cytomegalovirus infection after allogeneic hematopoietic stem cell transplantation by an ultrasensitive plasma DNA PCR assay

Cytomegalovirus (CMV) DNA amplification assays in plasma have shown limited sensitivity compared to the detection of pp65 antigen in leukocytes. Our goal was to increase the sensitivity of a commercial CMV DNA PCR quantitative assay. After modification, the new assay was able to reproducibly detect 20 CMV DNA copies/ml of plasma. We compared this new ultrasensitive PCR assay with the standard PCR and the pp65 test for CMV detection and quantification in 22 consecutive allogeneic hematopoietic stem cell recipients. CMV infection or reactivation was detected in 84 of 319 (26%) samples by the ultrasensitive PCR assay compared to 38 of 319 (12%) samples by the pp65 assay (P < 0.01). All samples positive by the pp65 assay were positive by the ultrasensitive PCR, and CMV episodes were detected on average 4 days earlier and 7 days later than the first and the last pp65-positive test, respectively. In addition, during CMV episodes, the ultrasensitive assay identified positive samples that were inconsistently detected by the pp65 assay. The ultrasensitive assay was also much more sensitive than the standard PCR, with 26 versus 12% of CMV DNA-positive samples (P < 0.01). This assay improved the monitoring of CMV infection or reactivation in hematopoietic allogeneic stem cell recipients.

The role of immune reconstitution in cytomegalovirus infection

Cytomegalovirus (CMV) causes high morbidity and mortality in immunocompromised patients. The host immune response to CMV comprises specific and nonspecific cellular and humoral responses, but current knowledge supports a protective role only for cell-mediated immune responses. Although complete CMV eradication is unusual even in immunocompetent hosts, its morbidity can be limited by CMV-specific CD8+ cytotoxic lymphocytes supported by CD4+-mediated T lymphocyte helper activity. In patients with congenital or acquired deficiencies of cell-mediated immunity, recovery of CD4+ lymphocyte numbers and/or function coincides with cessation of CMV-associated morbidity. However, an immunological test that can predict protection against CMV disease across different types of high-risk patients is not yet available. In recent years, the introduction of antivirals active against CMV has improved the outcome of CMV disease. In addition, there is a continuous effort to develop CMV-specific immune-based therapies including vaccines and immune modulators such as cytokines, which may be of supplemental benefit in the control of CMV disease.

Cytomegalovirus-induced glomerular vasculopathy in renal allografts: a report of two cases

Cytomegalovirus (CMV) remains a major viral pathogen complicating renal transplantation. Tubulointerstitial nephritis is the commonly acknowledged and well-characterized pathologic feature of renal allograft CMV disease. There is controversy about whether there is a distinct entity as a CMV glomerulopathy in the absence of tubulointerstitial disease. We describe two patients with renal allograft dysfunction who displayed distinct features of CMV glomerular vasculopathy, in the absence of overt viral cytopathic changes involving the tubules.

Monitoring of viral load by quantitative plasma PCR during active cytomegalovirus infection of individual liver transplant patients

A quantitative PCR test, the Cobas Amplicor CMV Monitor, was used for the monitoring of viral load in the peripheral blood of 27 individual liver transplant patients and correlated with cytomegalovirus (CMV) pp65 antigenemia. Altogether, 243 specimens were analyzed. During the first 3 months, 20 patients showed PCR positivity which correlated with pp65 antigenemia. Of those, 13 patients developed symptomatic CMV infection 27 to 52 days after transplantation, with a significantly higher peak viral load in PCR and in pp65 assay compared with the seven asymptomatic infections (median 10,200 versus 2,240 copies/ml, P < 0.05, and median 100 versus 30 pp65-positive cells/50,000 leukocytes, P < 0.01). Five were primary infections of D+/R- cases (donor CMV seropositive and recipient seronegative) and demonstrated, except in one case, a high peak viral load (>10,000 copies/ml; range, 10,200 to 21,600 copies, and > or =50 positive cells, range, 50 to 800 cells). The peak viral loads of the six D+/R+ patients with symptomatic infection varied widely (range, 2,290 to 126,000 copies and 50 to 300 positive cells). Two D-/R+ patients developed symptomatic infection with a lower viral load (range, 1,120 to 6,510 copies and 25 to 100 positive cells). All symptomatic infections were successfully treated with ganciclovir. The asymptomatic infections all in D+/R+ patients with low copy numbers (<5,500 copies) were monitored until CMV disappeared. One of the seven PCR-negative patients had one sample with low antigenemia, but the subsequent specimens were all negative. The time-related correlation of the two methods was also good. In summary, quantitative PCR could equally well be used as the CMV pp65 assay for the monitoring of viral load in individual transplant patients.