Cytomegalovirus Infection In Transplant Recipients Research Articles

Management of Cytomegalovirus Infections in the Era of the Novel Antiviral Players, Letermovir and Maribavir.

Cytomegalovirus (CMV) infections may increase morbidity and mortality in immunocompromised patients. Until recently, standard antiviral drugs against CMV were limited to viral DNA polymerase inhibitors (val)ganciclovir, foscarnet and cidofovir with a risk for cross-resistance. These drugs may also cause serious side effects. This narrative review provides an update on new antiviral agents that were approved for the prevention and treatment of CMV infections in transplant recipients. Letermovir was approved in 2017 for CMV prophylaxis in CMV-seropositive adults who received an allogeneic hematopoietic stem cell transplant. Maribavir followed four years later, with an indication in the treatment of adult and pediatric transplant patients with refractory/resistant CMV disease. The target of letermovir is the CMV terminase complex (constituted of pUL56, pUL89 and pUL51 subunits). Letermovir prevents the cleavage of viral DNA and its packaging into capsids. Maribavir is a pUL97 kinase inhibitor, which interferes with the assembly of capsids and the egress of virions from the nucleus. Both drugs have activity against most CMV strains resistant to standard drugs and exhibit favorable safety profiles. However, high-level resistance mutations may arise more rapidly in the UL56 gene under letermovir than low-grade resistance mutations. Some mutations emerging in the UL97 gene under maribavir can be cross-resistant with ganciclovir. Thus, letermovir and maribavir now extend the drug arsenal available for the management of CMV infections and their respective niches are currently defined.

Evaluation of Performance Characteristics of the Aptima CMV Quant Assay for the Detection and Quantitation of CMV DNA in Plasma Samples.

Quantification of Cytomegalovirus (CMV) DNA has become the standard of care in the diagnosis and management of CMV infection in transplant recipients. The objective of the study was to evaluate performance characteristics of the Aptima CMV Quant assay in comparison to Abbott RealTime CMV assay, Qiagen Artus CMV RGQ MDx assay, and Roche cobas CMV test using plasma samples. The performance of the Aptima assay was evaluated by comparing the Exact Diagnostics CMV verification panel and positive controls, Hologic CMV internal reproducibility panel, and SeraCare CMV DNA qualification panel to the RealTime assay. Clinical agreement was evaluated using 389 clinical plasma samples comparing the Aptima assay to three comparator assays. The Aptima assay demonstrated good linearity and strong linear correlation between the assays (R2 = 0.99); the intra- and interassay reproducibility was excellent overall (SD = 0.09 to 0.14 and SD = 0.04 to 0.14, respectively); 95% limit of detection (LOD) is 32 IU/mL and LOQ is 45 IU/mL. The SeraCare qualification panel yielded a strong linear correlation (R2 = 0.99). A total of 262 positive samples were analyzed to compare Aptima and Realtime assays using Deming regression and Bland-Altman analysis and demonstrated a mean bias of 0.092 Log10 IU/mL. Artus (85) and cobas (159) positive samples were compared to the Aptima assay using Deming regression and Bland-Altman analyses and showed mean bias of 0.184 and -0.208 Log10 IU/mL, respectively. The findings demonstrate that the Aptima assay is sensitive and accurate in quantifying CMV in plasma specimens on the fully automated Panther system and that the results were comparable to the other FDA-approved CMV assays.

Effectiveness of Prophylactic Human Cytomegalovirus Hyperimmunoglobulin in Preventing Cytomegalovirus Infection following Transplantation: A Systematic Review and Meta-Analysis.

Cytomegalovirus (CMV) is a common infection occurring in patients undergoing solid organ transplantation (SOT) or hematopoietic stem cell transplantation (HSCT). CMV-specific hyperimmunoglobulin (CMVIG) has been used for the past four decades and is typically administered either prophylactically or pre-emptively. The present meta-analysis evaluated CMV infection rates in SOT patients who received prophylactic CMVIG. PubMed and the Cochrane Library were searched for studies published up to October 2021. The primary endpoint was CMV infection rate. Thirty-two SOT studies were identified (n = 1521 CMVIG-treated and n = 1196 controls). Prophylactic CMVIG treatment was often associated with a lower risk of CMV infection in transplant recipients. The average CMV infection rate was 35.8% (95% confidence interval [CI]: 33.4–38.2%) in patients treated prophylactically with CMVIG and 41.4% (95% CI: 38.6–44.2%) in the control group not receiving CMVIG (p = 0.003). Similar results were observed in analyses limited to publications evaluating currently available CMVIG products (Cytotect CP and Cytogam; p < 0.001). In combination with the established safety profile for CMVIG, these results suggest that prophylactic CMVIG treatment in patients undergoing solid organ transplantation may be beneficial, particularly in those at high risk of CMV infection or disease.

Characteristics of viral infection and cytomegalovirus infection of transplant recipients

Characteristics of viral infection and cytomegalovirus infection of transplant recipients

Letermovir treatment of cytomegalovirus infection or disease in solid organ and hematopoietic cell transplant recipients.

Few options are available for cytomegalovirus (CMV) treatment in transplant recipients resistant, refractory, or intolerant to approved agents. Letermovir (LET) is approved for prophylaxis in hematopoietic cell transplant (HCT) recipients, but little is known about efficacy in CMV infection. We conducted an observational study to determine the patterns of use and outcome of LET treatment of CMV infection in transplant recipients. Patients who received LET for treatment of CMV infection were identified at 13 transplant centers. Demographic and outcome data were collected. Twenty-seven solid organ and 21 HCT recipients (one dual) from 13 medical centers were included. Forty-five of 47 (94%) were treated with other agents prior to LET, and 57% had a history of prior CMV disease. Seventy-seven percent were intolerant to other antivirals; 32% were started on LET because of resistance concerns. Among 37 patients with viral load<1000 international units (IU)/ml at LET initiation, two experienced>1 log rise in viral load by week 12, and no deaths were attributed to CMV. Ten patients had viral load>1000 IU/ml at LET initiation, and six of 10 (60%) had a CMV viral load<1000 IU/ml at completion of therapy or last known value. LET was discontinued in two patients for an adverse event. Patients treated with LET with viral load<1000 IU/ml had good virologic outcomes. Outcomes were mixed when LET was initiated at higher viral loads. Further studies on combination therapy or alternative LET dosing are needed.

1383. Everolimus is Associated with an Increased Risk of Tuberculosis in Solid-Organ Transplant Recipients

BackgroundTuberculosis (TB) is an important post-transplant infection. Everolimus has been documented to reduce the risk of cytomegalovirus infection in transplant recipients, but its impact on other infections is less known. The present study aimed to assess immunosuppressive regimens on TB risk in solid-organ transplant (SOT) recipients via a matched case–control study.MethodsFrom May 2005 to December 2018, SOT recipients with TB were retrospectively identified, and those without TB undergoing transplantation at the same university hospital were selected as controls. Controls and cases were matched by age (±5 years), transplant type and year (±5 years) at a ratio of 4:1. Conditional logistic regression was used to analyze the risk factors of TB.ResultsTB developed in 30 SOT recipients (13 kidney, 7 heart, 6 liver, and 4 lung) after a mean duration of 1,601 days after transplantation, with predominant lung involvement (87%). The diagnosis was made by culture in 70% and pathology in 17%. Rifamycins-based regimens were used in 27 cases, and 4 developed rejection without graft failure. A total of 106 controls were selected. At the time of TB diagnosis, cases were more likely to use everolimus than controls (27% vs. 11%, P < 0.05), but no significant differences were observed in the use of tacrolimus, cyclosporin, sirolimus, prednisolone, or mycophenolate mofetil. The median duration of everolimus use was 585 and 698 days in 8 cases and 12 controls, respectively. Multivariable analysis showed that everolimus use (adjust odds ratio [aOR] 22.3, 95% conference interval [CI] 2.5–203.0) and hemodialysis (aOR 19.6, 95% CI 1.3–287.1) were independently associated with TB.ConclusionTB is more likely to develop in SOT recipients on everolimus and hemodialysis. Further studies to confirm our findings are warranted, and TB risk assessment should be performed for those receiving everolimus and hemodialysis.Disclosures All authors: No reported disclosures.

Maribavir for Preemptive Treatment of Cytomegalovirus Reactivation

BackgroundMaribavir is a benzimidazole riboside with activity against cytomegalovirus (CMV). The safety and efficacy of maribavir for preemptive treatment of CMV infection in transplant recipients is not known.MethodsIn a phase 2, open-label, maribavir dose–blinded trial, recipients of hematopoietic-cell or solid-organ transplants (≥18 years of age, with CMV reactivation [1000 to 100,000 DNA copies per milliliter]) were randomly assigned to receive maribavir at a dose of 400, 800, or 1200 mg twice daily or the standard dose of valganciclovir for no more than 12 weeks. The primary efficacy end point was the percentage of patients with a response to treatment, defined as confirmed undetectable CMV DNA in plasma, within 3 weeks and 6 weeks after the start of treatment. The primary safety end point was the incidence of adverse events that occurred or worsened during treatment.ResultsOf the 161 patients who underwent randomization, 159 received treatment, and 156 had postbaseline data available — 117 in the maribavir group and 39 in the valganciclovir group. The percentage of patients with postbaseline data available who had a response to treatment within 3 weeks was 62% among those who received maribavir and 56% among those who received valganciclovir. Within 6 weeks, 79% and 67% of patients, respectively, had a response (risk ratio, 1.20; 95% confidence interval, 0.95 to 1.51). The percentages of patients with a response to treatment were similar among the maribavir dose groups. Two patients who had a response to treatment had a recurrence of CMV infection within 6 weeks after starting maribavir at a dose of 800 mg twice daily; T409M resistance mutations in CMV UL97 protein kinase developed in both patients. The incidence of serious adverse events that occurred or worsened during treatment was higher in the maribavir group than in the valganciclovir group (52 of 119 patients [44%] vs. 13 of 40 [32%]). A greater percentage of patients in the maribavir group discontinued the trial medication because of an adverse event (27 of 119 [23%] vs. 5 of 40 [12%]). A higher incidence of gastrointestinal adverse events was reported with maribavir, and a higher incidence of neutropenia was reported with valganciclovir.ConclusionsMaribavir at a dose of at least 400 mg twice daily had efficacy similar to that of valganciclovir for clearing CMV viremia among recipients of hematopoietic-cell or solid-organ transplants. A higher incidence of gastrointestinal adverse events — notably dysgeusia — and a lower incidence of neutropenia were found in the maribavir group. (Funded by ViroPharma/Shire Development; EudraCT number, 2010-024247-32.)

Improving our mechanistic understanding of the indirect effects of CMV infection in transplant recipients.

Cytomegalovirus (CMV) is an immunomodulatory virus that indirectly increases the risk for bacterial, fungal, and viral infections. However, the pathogenesis of this phenomenon is poorly understood. We determined whether inflammatory responses to different Toll-like receptor (TLR) ligands are blunted during CMV infection in solid-organ transplant (SOT) patients. Peripheral blood mononuclear cells from 38 SOT patients with and without CMV were incubated in the presence of various viral, fungal, and bacterial TLR ligands. Cytokines were measured in the supernatant by multiplex enzyme-linked immunosorbent assay. Patients had blunted cytokine responses to bacterial, fungal, and viral ligands during CMV infection when compared to the absence of CMV infection. This was independent of viral load, clinical presentation of CMV infection or immunosuppression, supporting the clinical observation in SOT recipients that CMV infection increases susceptibility to bacterial, fungal, and other viral infections. Moreover, in the absence of CMV infection, patients with subsequent CMV infection had lower cytokines in response to TLR ligands compared to those without subsequent CMV infection, suggesting that inherent differences in patients not directly related to CMV also contribute to this increased susceptibility. In summary, these data provide novel ex vivo evidence to support indirect effects of CMV.

Diagnostic Utility of Cytomegalovirus Nucleic Acid Testing during Antigenemia-Guided Cytomegalovirus Monitoring after Hematopoietic Stem Cell Transplantation or Liver Transplantation.

Cytomegalovirus (CMV) is an opportunistic pathogen, and careful monitoring of CMV is important for immunocompromised patients. Antigenemia-based CMV monitoring is a standard test used for managing CMV infection in transplant recipients; however, in Japan, there are no reports of CMV monitoring using the standardized test. The utility of a standardized CMV nucleic acid test (NAT) was evaluated during antigenemia-based CMV monitoring after hematopoietic stem cell transplantation (HSCT) or liver transplantation. Blood collection for CMV monitoring was performed under the physician's instructions depending on the condition of the patient, and CMV NAT and antigenemia was evaluated. For HSCT recipients, blood collection only for NAT was additionally performed during the pre-engraftment phase. The results of the NAT were blinded to those evaluating the results. A total of 34 patients were enrolled (11 HSCT recipients and 23 liver transplant recipients). NAT detected the first CMV episode no later than antigenemia in 2 (18.2%) HSCT recipients and 3 (13.0%) liver transplant recipients, earlier than antigenemia in 3 (27.3%) HSCT recipients and 7 (30.4%) liver transplant recipients, and later than antigenemia in 1 (9.1%) HSCT recipient and 1 (4.3%) liver transplant recipient. In 5 HSCT recipients, NAT was positive during the pre-engraftment phase. Among the 468 blood samples which were evaluated by both NAT and antigenemia, 124 (26.7%) were positive in NAT and 51 (10.9%) were positive in antigenemia. The standardized CMV NAT is useful for accurately diagnosing CMV infection and determining appropriate therapeutic interventions for HSCT recipients and liver transplant recipients.

Everolimus delayed and suppressed cytomegalovirus DNA synthesis, spread of the infection, and alleviated cytomegalovirus infection

Everolimus is an inhibitor of mammalian target of rapamycin (mTOR) and reduces the risk of cytomegalovirus (CMV) infection in transplant recipients. Everolimus inhibits mTOR complex 1, which regulates factors involved in several crucial cellular functions and is required for CMV replication. However, it is not clear how everolimus regulates CMV replication and prevents and alleviates CMV infection. Effects of everolimus on CMV infection, spread, and DNA synthesis and release from infected cells were assessed by plaque formation, infectious centre assay, real-time PCR of infected cells, and culture supernatant in CMV-infected cultures with and without everolimus. Everolimus enhanced plaque formation by 3.6 times, but the size of the plaques was reduced to 36.4% of untreated cultures in the absence of a pretreatment period. Everolimus reduced viral adsorption but enhanced the replication efficiency of inoculated virus, resulting in an increase in plaque number in the early phase of infection. Preinfection treatment of cells with everolimus efficiently exhibited its antiviral efficacy, and everolimus delayed and suppressed viral DNA synthesis and release from infected cells. Everolimus had suppressed the spread of infection and reduced the number of total infected cells to 40% of untreated cells on day 9, indicating reduction of the size of CMV lesions to one-sixth in 2–3 replication cycles. Preinfection treatment of the cells with everolimus augmented its suppressive effect on CMV infection and replication. Everolimus reduced the total number of infected cells and limited the CMV lesions, and this reduction in the spread of CMV infection would alleviate CMV infection in transplant recipients.

Going beyond serology for stratifying the risk of CMV infection in transplant recipients.

Knowledge of donor and recipient (D/R) cytomegalovirus (CMV) serostatus is critical for risk stratification of CMV infection and disease in transplant recipients, particularly in the solid organ transplantation (SOT) setting. Despite its broad availability and the success of it use, the risk stratification based on the D/R serostatus is not free of limitations since there are a nondepreciable number of patients that are not accurately categorized by this approach. In fact, up to 20% of seropositive SOT recipients, classically considered at intermediate risk, develop episodes of CMV infection and disease after transplantation. Here, we provide an overview of additional donor and recipient factors that may have utility in identifying patients at risk for post-transplant CMV infection. Specifically, we summarize our current understanding regarding the potential use of use CMV-specific T-cell-mediated immunity, neutralizing antibodies and host genetics that may influence the risk of CMV infection and disease. We provide an overview of the benefits and limitations associated with using these immunological factors in risk stratification and propose specific variables that could be analyzed at the pretransplant evaluation to improve the identification of patients with increased individual susceptibility.

Cytomegalovirus infection in transplant recipients

Cytomegalovirus infection is a frequent complication after transplantation. This infection occurs due to transmission from the transplanted organ, due to reactivation of latent infection, or after a primary infection in seronegative patients and can be defined as follows: latent infection, active infection, viral syndrome or invasive disease. This condition occurs mainly between 30 and 90 days after transplantation. In hematopoietic stem cell transplantation in particular, infection usually occurs within the first 30 days after transplantation and in the presence of graft-versus-host disease. The major risk factors are when the recipient is cytomegalovirus seronegative and the donor is seropositive as well as when lymphocyte-depleting antibodies are used.There are two methods for the diagnosis of cytomegalovirus infection: the pp65 antigenemia assay and polymerase chain reaction. Serology has no value for the diagnosis of active disease, whereas histology of the affected tissue and bronchoalveolar lavage analysis are useful in the diagnosis of invasive disease.Cytomegalovirus disease can be prevented by prophylaxis (the administration of antiviral drugs to all or to a subgroup of patients who are at higher risk of viral replication) or by preemptive therapy (the early diagnosis of viral replication before development of the disease and prescription of antiviral treatment to prevent the appearance of clinical disease). The drug used is intravenous or oral ganciclovir; oral valganciclovir; or, less frequently, valacyclovir. Prophylaxis should continue for 90 to 180 days. Treatment is always indicated in cytomegalovirus disease, and the gold-standard drug is intravenous ganciclovir. Treatment should be given for 2 to 3 weeks and should be continued for an additional 7 days after the first negative result for viremia.

1168Use of First Positive Cytomegalovirus (CMV) PCR Determination to Differentiate a Viral Blip From Established CMV Infection in Transplant Recipients

1168Use of First Positive Cytomegalovirus (CMV) PCR Determination to Differentiate a Viral Blip From Established CMV Infection in Transplant Recipients

Cytomegalovirus-responsive γδ T cells: novel effector cells in antibody-mediated kidney allograft microcirculation lesions.

Human cytomegalovirus infection in transplant recipients has been associated with adverse renal allograft outcome and with a large γδ T-cell response, but whether both mechanisms are connected is unknown. We previously showed that most expanded circulating cytomegalovirus-responsive γδ T cells express the Fcγ-receptor CD16, suggesting that γδ T cells may participate in allograft lesions mediated by donor-specific antibodies through antibody-dependent cellular cytotoxicity. Here, we show that cytomegalovirus-specific CD16(pos) γδ T cells can perform antibody-dependent cellular cytotoxicity against stromal cells coated with donor-specific antibodies in vitro. In vivo, graft-infiltrating γδ T cells localized in close contact with endothelial cells only in patients who experienced cytomegalovirus infection and were more frequent within peritubular capillaries and glomeruli from antibody-mediated acute rejections than within those from T cell-mediated acute rejections. Finally, a persistently increased percentage of circulating cytomegalovirus-induced γδ T cells correlated inversely with the 1-year eGFR only in kidney recipients with donor-specific antibodies. Collectively, these data support the conclusion that cytomegalovirus-induced γδ T cells are involved in, and may serve as a clinical biomarker of, antibody-mediated lesions of kidney transplants. Moreover, these findings offer a new physiopathologic link between cytomegalovirus infection and allograft dysfunction in recipients with donor-specific antibodies.

Clinical Utility of Viral Load in Management of Cytomegalovirus Infection after Solid Organ Transplantation

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

Development of a therapeutic vaccine to prevent cytomegalovirus infection in transplant recipients

August 20-22, 2012 A is a DNA vaccine designed to prevent cytomegalovirus (CMV) infection in both hematopoietic and solid organ transplant recipients at risk for CMV disease. The vaccine consists of two plasmids which encode the tegument protein pp65 and the surface protein gB of CMV. pp65 induces cell-mediated responses and gB induces humoral responses in persons infected with CMV. A Phase 1, dose-ranging trial evaluated safety and immunogenicity of the vaccine in CMV-seronegative and CMVseropositive healthy volunteers. No significant safety events occurred and a cultured ELISPOT assay detected T cell responses in 56-62.5 % of seronegative subjects. A Phase 2 exploratory, double-blind, placebo-controlled trial evaluated the efficacy, immunogenicity, and safety of the vaccine in cytomegalovirus-seropositive hematopoietic cell recipients. 108 transplant recipients received the vaccine. The efficacy population comprises 74 subjects: 34 in the placebo arm and 40 in the ASP0113 treatment arm. The safety population comprises the 108 subjects treated. 19 (48%) of the ASP0113 recipients received cytomegalovirusspecific CMV anti-viral therapy compared with 21 (62%) of placebo recipients (p=0.145). 13(33%) of the ASP0113 recipients reached > 500 copies/mL of CMV by central assay compared with 21 (62%) of placebo recipients (p=0.008). In addition, there was a reduction in the number of CMV infection episodes (p=0.017) and the time to initial viremia (p=0.003). One subject discontinued the vaccine after a hypersensitivity reaction but responded well to conservative medical therapy. Based on these positive findings, further evaluation of the efficacy and safety of the vaccine is planned.

Universal Prophylaxis With Gancyclovir Preparation Is Not Necessary in Our Kidney Allograft Recipients

Background Cytomegalovirus (CMV) infection is a common cause of morbidity, graft loss, and mortality among kidney recipients due to its direct and indirect influences on organs and systems. In this study, we evaluated CMV infection in transplant recipients in Iran. Materials and methods We performed a retrospective study of 104 renal allograft recipients and their donors transplanted between January 2005 and January 2010. We included all patients (recipients and donors) with least one valid laboratory result for CMV immunoglobulin (Ig)G and CMV IgM. We evaluated the occurrence of CMV disease in allograft recipients in at least the first 3 years after renal transplantation. Results Fifty-seven renal allograft recipients (54.8%) were males and 47 (45.2%) were females. The overall mean (± standard error) age was 40.32 ± 13.30 years. CMV IgG was positive in 95 cases (91.3%), negative in 9 (8.7%). Serologically, 76.9% patients were D +/R + 14.4% D −/R +, and 8.7% D +R −. Due to the proccurrence of rejection rendering them high-risk patients for CMV infection about 15% of subjects were treated with anti thymocyte globulin (ATG) followed by prophylactic intravenous gancyclovir for 2 weeks, at doses based on allograft function. Confirmed CMV infection and CMV disease occurred in less than 5% of recipients in the first year after transplantation. About 6% of renal allograft recipients died due to infections during the first 3 years posttransplantation but CMV disease was not confirmed in these patients. Conclusion Due to the living donor-based renal transplantation program, the selection of low-risk patients (panel-reactive antibodies 30%), the low percent of D +/R − patients (8.7%) and the low use of ATG for induction therapy in the Iranian model, universal prophylaxis with gancyclovir is not routinely recommended for our cases.

Oral maribavir for treatment of refractory or resistant cytomegalovirus infections in transplant recipients

Despite advances in cytomegalovirus (CMV) prophylaxis and therapy, some transplant recipients still develop refractory CMV infections. Maribavir (MBV), an investigational benzimidazole antiviral agent, acts by a mechanism different from that of existing anti-CMV drugs. Previous Phase I and II studies have demonstrated a favorable safety profile for MBV, but its utility in treatment of complex CMV syndromes is unknown. Between June and December 2008, MBV was released for use under individual emergency investigational new drug applications requested by treating physicians and approved by the US Food and Drug Administration and local institutional review boards. Six patients (5 solid organ transplant recipients and 1 hematopoietic stem cell transplant recipient) who had failed to respond to other therapies and/or had known ganciclovir-resistant CMV were treated with MBV at a starting oral dose of 400 mg twice daily. Patients were treated for a median of 207 days (range, 15-376). Four of 6 patients had no detectable CMV DNAemia within 6 weeks of starting MBV therapy. One patient, who had an initial viral load of 1.8 million copies/mL, developed MBV resistance mutations. One patient, who had low serum levels of MBV, had persistent CMV DNAemia and viruria without developing genotypic or phenotypic resistance to MBV. One patient cleared CMV DNAemia, but died of pneumonia and multiorgan failure. No significant adverse effects attributable to MBV were observed. MBV deserves further systematic evaluation as treatment for CMV infection that is resistant and/or refractory to standard therapies, but its optimal dose, duration of therapy, and use in combinations versus as a single agent have yet to be determined.

Novel Anticytomegalovirus Activity of Immunosuppressant Mizoribine and Its Synergism with Ganciclovir

Cytomegalovirus (CMV) infection is a prominent infection in transplant recipients. The immunosuppressive drug mizoribine was shown to have anti-CMV activity in vitro and was reported to have an anti-CMV effect in renal transplantation. This study characterized the anti-CMV activity of mizoribine in vitro and its synergistic activity with ganciclovir. Mizoribine suppressed replication and at the EC(50) for plaque inhibition of 12.0 microg/ml. Mizoribine and ganciclovir exerted a strong synergism in anti-CMV activity. Mizoribine depletes guanosine nucleotides by inhibiting inosine monophosphate dehydrogenase and may increase the ratio of ganciclovir to guanosine in treated cells, resulting in a strong synergistic augmentation of the anti-CMV activity of ganciclovir. Two clinical isolates with UL97 mutations were less susceptible to mizoribine than the Towne strain but were equally susceptible in the presence of guanine. Two mizoribine-resistant strains were isolated after culture for 3 months with 100 microg/ml mizoribine, but they were as sensitive to ganciclovir as the parent Towne strain. The anti-CMV activity of mizoribine was antagonized by 2'-deoxyguanosine. Mizoribine inhibited CMV replication directly, and the sequence of mizoribine-resistant mutants of UL97 and UL54 was identical to that of the parent Towne strain, indicating the different anti-CMV action from ganciclovir, foscarnet, and maribavir. Mizoribine as an immunosuppressive and anti-CMV drug in the clinical regimen was suggested to suppress replication of CMV in vivo and control CMV infection in transplant recipients in combination with ganciclovir.

The Best Practices for Screening, Monitoring, and Diagnosis of Cytomegalovirus Disease, Part II

Abstract Human cytomegalovirus (CMV), a ubiquitous member of the herpesvirus family, is an important human pathogen. Infections are usually asymptomatic but can be associated with a wide spectrum of diseases, particularly in immunocompromised persons. Primary infection during pregnancy may result in congenital infection, leading to severe damage to the fetus. Intrauterine primary infections are second only to Down's syndrome as a known cause of mental retardation. CMV infection in transplant recipients may cause different clinical syndromes in different groups of patients, and the severity of the infection parallels the degree of immunosuppression. As infections are either asymptomatic or accompanied by symptoms that are not specific to CMV (such as fever and leukopenia), laboratory techniques are the sole means of diagnosing CMV infection. Diagnosis of CMV infection can be made directly by demonstration of the virus or virus components directly in clinical samples or indirectly through serology. Part II of this article focuses on congenital CMV infections, including diagnosis in the mother during various stages of pregnancy and diagnosis in the fetus and newborn.