A prospective study of the natural course of cytomegalovirus infection and disease in renal allograft recipients

Cytomegalovirus infection in solid organ transplantation

Cytomegalovirus infection remains a serious threat to solid transplant recipients. Despite advances in this field, there are still difficulties in the diagnosis of the disease and there are questions about the best and most cost-effective strategy to prevent infection and its direct and indirect consequences in the short and long term. All these points are discussed and updated in this chapter.

Six-month low-dose valganciclovir prophylaxis in cytomegalovirus D+/R- kidney transplant patients receiving thymoglobulin induction

BACKGROUND

The use of T-cell-depleting antibody, such as thymoglobulin, is a risk factor for cytomegalovirus (CMV) infection. We studied the effectiveness of 6 months of low-dose valganciclovir prophylaxis in CMV-naive kidney transplant recipients of CMV-positive donor kidney (D+/R-) receiving thymoglobulin induction.

METHODS

We included all D+/R- kidney transplant patients between October 2005 and December 2010 who received valganciclovir 450 mg daily for 6 months as per center protocol. CMV infection was confirmed by positive viremia. Kaplan-Meier and multivariate Cox proportional regression analyses were employed to compare the risk of CMV infection between patients with and without the use of thymoglobulin induction.

RESULTS

Out of 170 D+/R- kidney transplant patients, 42 cases of CMV infection (24.6%) were diagnosed after a median follow-up of 3.2 years: six patients from the noninduction (9.4%) and 36 from the induction cohort (34.0%). The induction with thymoglobulin was associated with four times greater risk of developing CMV infection (adjusted hazard ratio: AHR 4.15, 95% 1.75, 9.86, P = .001). The use of thymoglobulin was associated with leukopenia but not neutropenia.

CONCLUSIONS

Additional measures are needed to reduce the elevated incidence of CMV infection in D+/R- kidney transplant patients receiving induction with thymoglobulin.

Correlation and clinical utility of pp65 antigenemia and quantitative polymerase chain reaction assays for detection of cytomegalovirus in pediatric renal transplant patients

qPCR and pp65 antigenemia assays are used to monitor CMV infection in renal transplant recipients, but correlation of assays in a pediatric population has not been evaluated. Paired CMV real-time qPCR and pp65 antigenemia tests from 882 blood samples collected from 115 pediatric renal transplant recipients were analyzed in this retrospective cohort study for the strength of association and clinical correlates. The assays correlated well in detecting infection (κ = 0.61). Higher qPCR values were demonstrated with increasing levels of antigenemia (p < 0.01). Discordant test results were associated with antiviral treatment (OR 4.33, p < 0.01) and low-level viremia, with odds of concordance increasing at higher qPCR values (OR 3.67, p < 0.01), and no discordance occurring above 8500 genomic equivalents/mL. Among discordant samples, neither test preceded the other in detecting initial infection or in returning to negative while on treatment. Only two cases of disease occurred during the two-yr study period. With strong agreement in the detection of CMV infection, either qPCR or pp65 antigenemia assays can be used effectively for monitoring pediatric renal transplant patients for both detection and resolution of infection.

[Risk factors for cytomegalovirus in solid organ transplant recipients]

Cytomegalovirus (CMV) is the most important opportunistic pathogen in patients undergoing solid organ transplantation and increases mortality due to both direct and indirect effects. The most important risk factor for the development of CMV disease is discordant donor-recipient CMV serology (positive donor and negative recipient), which confers more than 50% risk of developing CMV disease if no prophylaxis is given. The use of highly potent antiviral agents for CMV prophylaxis in high-risk patients has changed the characteristics of CMV disease in this population. Other classical risk factors for CMV disease include acute graft rejection, the type of organ transplanted, coinfection with other herpesviruses and the type of immunosuppressive agents employed. New risk factors for this complication have recently been described, including variations in the CMV genotype between donor and recipient and genetic alterations in the recipient's innate immunity. The present review discusses classical risk factors and the latest findings reported on the development of CMV in organ transplant recipients.

Cytomegalovirus disease in kidney transplant recipients: incidence, clinical profile, and risk factors

BACKGROUND

Cytomegalovirus (CMV) is one of the most frequently encountered opportunistic viral pathogens in renal transplantation. Approximately 60% of transplant recipients will have CMV infection and >20% will develop symptomatic disease. With the advancement of immunosuppression, variation in the occurrence and pattern of infections is possible. We described the incidence, clinical profile, outcome, and risk factors for development of CMV disease among renal transplant recipients.

PATIENTS AND METHODS

We studied patients who underwent transplantation from January 2005-December 2009 admitted for CMV disease. CMV infection was present if the patient had at least 1 of the following: positive early antigen detection in blood or tissues, positive CMV antigenemia, or a 4-fold increase in pretransplantation CMV antibody titer. CMV disease was diagnosed if CMV infection was accompanied by clinical signs and symptoms. Descriptive statistics included measures of central tendency for continuous numerical variables and percentage-frequency distribution for categorical variables z test, Wilcoxon-Mann-Whitney test, and Fisher exact test were used to determine risk factors for CMV disease.

RESULTS

About 1502 renal transplantations were done during the study period with mean follow-up of 33.8 months. CMV disease was confirmed in 85 (5.8%) recipients who developed 88 CMV disease episodes. Of the 85 patients who had CMV disease, 55% developed ≤ 3 months posttransplantation. Fever was the most common presenting symptom, 53% had coinfection, and case fatality rate was 11%. Risk factors that were statistically significant in the development of CMV disease were as follows: recipient/donor relationship (P = .0115), CMV donor+/recipient- (P = .004), and recent rejection treatment (P = .0084).

CONCLUSION

Incidence of CMV disease was 5.8% with fever as the most common presenting symptom and 55% developed CMV disease ≤ 3 months posttransplantation. Coinfection occurred in 53% and case fatality rate in 11%. Risk factors for developing CMV disease included CMV donor+/recipient- and recent acute rejection treatment.

Historical comparison of prophylactic ganciclovir for gastrointestinal cytomegalovirus infection in kidney transplant recipients

BACKGROUND

Cytomegalovirus (CMV) can cause morbidity in kidney transplant recipients. The gastrointestinal (GI) tract is a major target for CMV disease. The aim of this study was to evaluate the benefit of ganciclovir prophylaxis on GI CMV infection in intermediate-risk CMV seropositive transplant recipients.

METHODS

Since January 2009, intravenous ganciclovir (5 mg/kg, twice daily) was administered for 14 days after kidney transplantation in 41 patients. The historical control group consisted of 45 patients who received kidney transplantations between January 2007 and December 2008. To evaluate the effects of prophylaxis on GI CMV infection, we performed routine endoscopic examinations with mucosal biopsies at the time of transplantation as well as 1, 3, and 6 months thereafter.

RESULTS

The average age of the 86 studied patients was 43.7 ± 10.6 years (range = 14-63) and the male-to-female ratio 1:1.3. Forty-three (50%) patients underwent deceased donor transplantations and 84 (97.7%) patients were CMV seropositive at that time. The incidence of GI CMV infection was significantly lower among the prophylaxis than the historical control group (24.4% vs 48.9%, P = .026). Patient age, numbers of deceased donors, and tacrolimus trough levels at 1 and 3 months posttransplant were significantly lower in the prophylaxis than the historical control group. Logistic regression analysis revealed ganciclovir prophylaxis to be the only significant risk factor for GI CMV infection.

CONCLUSION

Prophylactic treatment with ganciclovir decreased the incidence GI CMV infection among seropositive kidney transplant recipients.

The chromatin remodeling factor SMARCB1 forms a complex with human cytomegalovirus proteins UL114 and UL44

BACKGROUND

Human cytomegalovirus (HCMV) uracil DNA glycosylase, UL114, is required for efficient viral DNA replication. Presumably, UL114 functions as a structural partner to other factors of the DNA-replication machinery and not as a DNA repair protein. UL114 binds UL44 (HCMV processivity factor) and UL54 (HCMV-DNA-polymerase). In the present study we have searched for cellular partners of UL114.

METHODOLOGY/PRINCIPAL FINDINGS

In a yeast two-hybrid screen SMARCB1, a factor of the SWI/SNF chromatin remodeling complex, was found to be an interacting partner of UL114. This interaction was confirmed in vitro by co-immunoprecipitation and pull-down. Immunofluorescence microscopy revealed that SMARCB1 along with BRG-1, BAF170 and BAF155, which are the core SWI/SNF components required for efficient chromatin remodeling, were present in virus replication foci 24-48 hours post infection (hpi). Furthermore a direct interaction was also demonstrated for SMARCB1 and UL44.

CONCLUSIONS/SIGNIFICANCE

The core SWI/SNF factors required for efficient chromatin remodeling are present in the HCMV replication foci throughout infection. The proteins UL44 and UL114 interact with SMARCB1 and may participate in the recruitment of the SWI/SNF complex to the chromatinized virus DNA. Thus, the presence of the SWI/SNF chromatin remodeling complex in replication foci and its association with UL114 and with UL44 might imply its involvement in different DNA transactions.

Modelling and optimal control of immune response of renal transplant recipients

We consider the increasingly important and highly complex immunological control problem: control of the dynamics of immunosuppression for organ transplant recipients. The goal in this problem is to maintain the delicate balance between over-suppression (where opportunistic latent viruses threaten the patient) and under-suppression (where rejection of the transplanted organ is probable). First, a mathematical model is formulated to describe the immune response to both viral infection and introduction of a donor kidney in a renal transplant recipient. Some numerical results are given to qualitatively validate and demonstrate that this initial model exhibits appropriate characteristics of primary infection and reactivation for immunosuppressed transplant recipients. In addition, we develop a computational framework for designing adaptive optimal treatment regimes with partial observations and low-frequency sampling, where the state estimates are obtained by solving a second deterministic optimal tracking problem. Numerical results are given to illustrate the feasibility of this method in obtaining optimal treatment regimes with a balance between under-suppression and over-suppression of the immune system.

Shedding light on the elusive role of endothelial cells in cytomegalovirus dissemination

Cytomegalovirus (CMV) is frequently transmitted by solid organ transplantation and is associated with graft failure. By forming the boundary between circulation and organ parenchyma, endothelial cells (EC) are suited for bidirectional virus spread from and to the transplant. We applied Cre/loxP-mediated green-fluorescence-tagging of EC-derived murine CMV (MCMV) to quantify the role of infected EC in transplantation-associated CMV dissemination in the mouse model. Both EC- and non-EC-derived virus originating from infected Tie2-cre(+) heart and kidney transplants were readily transmitted to MCMV-naïve recipients by primary viremia. In contrast, when a Tie2-cre(+) transplant was infected by primary viremia in an infected recipient, the recombined EC-derived virus poorly spread to recipient tissues. Similarly, in reverse direction, EC-derived virus from infected Tie2-cre(+) recipient tissues poorly spread to the transplant. These data contradict any privileged role of EC in CMV dissemination and challenge an indiscriminate applicability of the primary and secondary viremia concept of virus dissemination.

Impact of CMV infection on acute rejection and long-term renal allograft function: a systematic analysis in patients with protocol biopsies and indicated biopsies

BACKGROUND

Higher rates of acute rejection (AR) and reduced graft survival have been reported in patients with cytomegalovirus (CMV) infection, but an association between these factors remains controversial.

METHODS

In this study, serial protocol biopsies (PBs) and clinically indicated biopsies (IBs) from a large cohort of renal allograft recipients (n &frac14; 594) were analyzed to examine the relation between CMV and AR.

RESULTS

Patients with CMV were more likely to receive IB (85 of the 153 patients; 56%) compared to patients without CMV (138 of 441 patients; 32%; P = 0.003). However, this did not translate into a greater number of patients with episodes of acute cellular rejection on histopathology in IBs. Analysis of PBs revealed a significantly higher number of episodes of rejection per patient with CMV infection (P = 0.04), but only in a subgroup of patients with triple immunosuppression. Long-term graft function post-transplantation was analyzed in four different subgroups according to CMV infection and/or AR. Differences in renal function were apparent within the first 6 weeks after transplantation and persisted during follow-up, with the best renal function in patients without AR or CMV, whereas patients with both AR and CMV had the worst (P < 0.012 at 1 year; P < 0.001 at 2 years). On average, the latter group had significantly older donors and more often delayed graft function.

CONCLUSIONS

Our data suggests that the link between CMV and AR is far less significant than previously thought. Outcome in patients with CMV may be more determined by coexisting conditions like high donor age and delayed graft function.

Choice of induction regimens on the risk of cytomegalovirus infection in donor-positive and recipient-negative kidney transplant recipients

BACKGROUND

Late occurrence of cytomegalovirus (CMV) infection remains a concern in CMV-seronegative kidney and/or pancreas transplant recipients of CMV-seropositive organs (donor positive/recipient negative, D+/R-) despite the use of prophylaxis. We investigated the impact of various antibody induction regimens on CMV infection in this group of patients.

METHODS

A total of 254 consecutive D+/R- kidney and/or pancreas transplant patients were studied. The induction agents rabbit anti-thymocyte globulin (rATG) or basiliximab were used according to the center practice. All patients received prophylaxis with valganciclovir (VGCV) for either 3 or 6 months. The occurrence of CMV infection was confirmed by positive DNA viremia. Multivariate Cox regression analyses were performed to determine risk factors for CMV infection.

RESULTS

The cumulative incidence of CMV infection was 58, 112, and 59 cases per 1000 patient-years for patients who received no antibody induction, induction with rATG, or basiliximab induction, respectively (P=0.02). The use of rATG but not basiliximab was associated with an increased risk for CMV infection (adjusted hazard ratio [AHR] 2.13, 95% confidence interval [CI] 1.24-3.54, P=0.006). Acute rejection and its treatment with rATG were not associated with an increased risk for CMV infection when an additional course of VGCV was given following the treatment. Longer duration of prophylaxis was associated with a reduced risk for CMV infection (AHR 0.54, 95% CI 0.33-0.87, P=0.011).

CONCLUSIONS

Induction with rATG is associated with increased risk of CMV infection. Longer duration of prophylaxis is beneficial.

[Cytomegalovirus effects in solid organ transplantation and the role of antiviral prophylaxis]

Cytomegalovirus (CMV) belongs to β-Herpesviridae family. Morbidity related to this infectious agent remains a serious concern in the context of immunosuppression. Occurence of CMV infection within the first 3 months post-renal transplantation without any antiviral prophylaxis is about 70% of patients. Direct and indirect effects of CMV infection in the setting of organ transplantation are described in this review. A 3 to 6 months course of prophylaxis with valganciclovir is advised concerning high-risk transplant recipients (D+/R-) but recommendation regarding intermediate-risk transplant recipients (CMV-seropositive patients) is still unclear. Recent studies highlight a benefit of long time prophylaxis (until 6 months) in terms of CMV disease occurence among D+/R- patients. News assays that measures IFNγ responses to a variety of CMV epitopes (Quantiferon(®) and Elispot IFNγ) are developped to predict CMV disease onset after discontinuation of antiviral prophylaxis. These assays could contribute to adapt prophylaxis to each recipient.

Primary CMV infections are common in kidney transplant recipients after 6 months valganciclovir prophylaxis

Prolonging cytomegalovirus (CMV) prophylaxis in CMV seronegative recipients of a kidney from CMV seropositive donor (D+/R-) may reduce the incidence of late infections. We analyzed late-onset primary CMV infections after 6 months valganciclovir prophylaxis. Data from all CMV D+/R- kidney transplant recipients between January 2004 and December 2008 at our center were analyzed. Patients with a functioning graft at 6 months after transplantation who received 6 months of valganciclovir prophylaxis 900 mg once daily were included (N = 127). CMV was diagnosed with quantitative PCR. Prophylaxis was completed in 119 patients. Prophylaxis was stopped at 3-5 months due to leukopenia or gastrointestinal side effects in eight patients. Late-onset primary CMV infection developed in 47/127 (37%) patients median 244 days after transplantation (range 150-655) and median 67 days after the cessation of prophylaxis (range 1-475). Four infections were asymptomatic. In others, symptoms included fever (N = 28), gastrointestinal symptoms (nausea, vomiting, diarrhea) (N = 24), respiratory tract symptoms (N = 12), and hepatopathy (N = 6). Median peak viral load was 13500 copies/mL (range 400-2,831,000). Recurrent CMV infection developed in 9/47 (19%) patients. No significant risk factors for CMV infection were identified. Symptomatic primary CMV infections were commonly detected also after prolonged valganciclovir prophylaxis.

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

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

Incidence of and risk factors for posttransplant diabetes mellitus after pancreas transplantation

Posttransplant diabetes mellitus (PTDM) after pancreas transplantation (PTX) has not been extensively examined. This single center, retrospective analysis of 674 recipients from 1994 to 2005 examines the incidence of and risk factors for PTDM after PTX. PTDM was defined by fasting plasma glucose level > or =126 mg/dL, confirmed on a subsequent measurement or treatment with insulin or oral hypoglycemic agent for > or =30 days. The incidence of PTDM was 14%, 17% and 25% at 3, 5 and 10 years after PTX, respectively and was higher (p = 0.01) in solitary pancreas (PAN) versus simultaneous kidney pancreas (SPK) recipients (mean follow-up 6.5 years). In multivariate analysis, factors associated with PTDM were: older donor age (hazard ratio [HR] 1.04, 95% confidence interval [CI] 1.03-1.06, p < 0.001), higher recipient body mass index (HR 1.07,CI 1.01-1.13, p = 0.01), donor positive/recipient negative CMV status (HR 1.65,CI 1.03-2.6, p = 0.04), posttransplant weight gain (HR 4.7,CI 1.95-11.1, p < 0.001), pancreas rejection (HR 1.94.CI 1.3-2.9, p < 0.001) and 6 month fasting glucose (HR 1.01,CI 1.01-1.02, p < 0.001), hemoglobin A(1)c, (HR 1.12,CI 1.05-1.22, p = 0.002) and triglyceride to high-density lipoprotein (TG/HDL) ratio (HR 0.94,CI 0.91-0.96, p < 0.001). This study delineates the incidence and identifies risk factors for PTDM after PTX.

A new strategy of delayed long-term prophylaxis could prevent cytomegalovirus disease in (D+/R-) solid organ transplant recipients

Long-term prophylaxis against cytomegalovirus (CMV) started immediately after transplantation in (D+/R-) poses a higher risk of late-onset CMV disease. Delayed CMV prophylaxis could allow a transitory exposure of the immune system to CMV, which would let the immune system mount an adequate CMV-specific cytotoxic response in (D+/R-) patients and confer protection against CMV disease. We included all (D+/R-) solid organ transplant recipients (SOT) performed at our institution (January 3/October 6) who received CMV prophylaxis (mainly with oral valganciclovir) during 100 d. In the first period (until December 4), prophylaxis was initiated immediately after transplantation (conventional prophylaxis: CP). Since January 5, it was initiated after 14 d (delayed prophylaxis: DP). Incidence and severity of CMV disease was compared between both groups. A total of 44 SOT recipients were included (CP: 26 and DP: 18). CMV disease was diagnosed in eight patients (18%), seven of 26 (27%) in the CP group, and one of 18 (5.5%) in the DP group (p = 0.07). CMV colitis was reported in five of 26 patients in the CP group (19%), whereas there were no cases of visceral CMV disease in the DP group (p = 0.048). A 14-d delay in the beginning of long-term prophylaxis against CMV in (D+/R-) is safe and could prevent the onset of late-CMV disease.

Probabilistic modeling of cytomegalovirus infection under consensus clinical management guidelines

BACKGROUND

Cytomegalovirus (CMV) is the most common viral pathogen after renal transplantation and remains a major therapeutic challenge with important clinical and economic implications from both direct and indirect consequences of infection.

METHODS

This 5-year study modeled the relationship between CMV infection and biopsy-proven graft rejection, graft loss, or death after renal transplantation in an inception cohort using Canadian consensus guidelines for CMV management as a component of a detailed cost-analysis of viral infection.

RESULTS

Probabilities of CMV viremia and syndrome/disease among 270 sequential graft recipients were 0.27 and 0.09, respectively; 91% of cases occurred in the first 6 months. Probability of CMV infection as the first event was 0.29, with a probability of subsequent biopsy-proven acute rejection (BPAR) of 0.05 (mean: 62+/-26 days, range: 32-85 days), whereas the probability of BPAR as the first event was 0.18, with a probability of subsequent CMV infection of 0.38 (mean: 63+/-31, range: 27-119 days). Probability of freedom from both CMV infection and BPAR throughout the period of observation was 0.53. Time-dependent Cox analysis showed that neither donor/recipient CMV risk stratum nor CMV infection influenced the risks of BPAR (P=0.24; P=0.74) or of graft loss or death (P=0.26; P=0.34). In contrast, BPAR significantly increased the risk of both subsequent CMV infection (hazard ratio=1.77, P=0.03) and of graft loss or death (hazard ratio=8.31, P<0.0001).

CONCLUSIONS

Although current antiviral therapy seems to mitigate the reported deleterious effects of CMV infection on BPAR or graft survival, BPAR remains a significantly risk factor for both CMV infection and functional graft survival.

Association between a polymorphism in the IL-12p40 gene and cytomegalovirus reactivation after kidney transplantation

BACKGROUND

Cytomegalovirus (CMV) infection is associated with a significant rate of morbidity after organ transplantation. The genetic factors influencing its occurrence have been little investigated. IL-12 plays a crucial role in anti-infectious immune responses, especially by stimulating IFNgamma production. An A-to-C single nucleotide polymorphism (SNP) within the 3'-untranslated region of the IL-12p40 gene has been characterized and was reported to be both functionally and clinically relevant. However, the impact of this single nucleotide polymorphism on events after organ transplantation has never been reported.

METHODS

In this study, we investigated the impact of the 3'-untranslated region polymorphism on the occurrence of CMV infection in 469 kidney recipients transplanted at the University Hospital of Tours between 1995 and 2005. The polymorphism was genotyped using the restriction fragment length polymorphism method and CMV infection was determined by pp65 antigenemia.

RESULTS

Multifactorial Cox regression analysis demonstrated that the presence of the C allele was an independent risk factor for CMV infection (OR=1.52, P=0.043), the risk being even higher when study was restricted to patients with positive CMV serological status before the graft and who did not receive any CMV prophylaxis (OR=1.88, P=0.028).

CONCLUSIONS

This study identified a new genetic risk factor for CMV reactivation after kidney transplantation. The results of our study suggest that C carriers might especially benefit from CMV prophylaxis.

Impact of the complement lectin pathway on cytomegalovirus disease early after kidney transplantation

BACKGROUND

This study retrospectively investigated the association between pre-transplant levels of mannose-binding lectin (MBL) plus the associated serine protease (MASP)-2 and the occurrence of cytomegalovirus (CMV) infection and symptomatic CMV disease during the first 12 weeks after kidney transplantation. Materials and methods. Altogether 159 consecutive single kidney transplant recipients were included. The patients were screened for CMV pp65 antigenaemia every second week. No CMV prophylaxis or pre-emptive treatment was given. MBL and MASP-2 were measured in samples taken at transplantation and 10 weeks later.

RESULTS

CMV infection, defined as at least one positive test, was found in 95 patients (59.8%). MBL and MASP-2 measured at transplantation were similar in patients with and without CMV infection. The incidence of CMV infection was also similar in 36 patients (58.3%) with pre-transplant MBL levels below the reference level (500 microg/L) and in patients with higher MBL levels (60.2%). Symptomatic CMV disease was diagnosed in 35 patients (22%), and MASP-2 levels at transplantation in the lower quartile range (<or=148 microg/L) was significantly associated with CMV disease during the first 12 weeks, P = 0.028. MBL levels decreased significantly from transplantation to 10 weeks later, and median (interquartile range) fell from 2597 (526-4939) microug/L to 1520 (270-3069) microg/L (P < 0.001). In contrast, MASP-2 levels increased significantly from 252 (148-382) microg/L to 380 (302-492) microg/L (P < 0.001).

CONCLUSION

Pre-transplant MBL levels do not influence the incidence of any CMV infection or symptomatic CMV disease during the first 12 weeks after kidney transplantation. However, low MASP-2 levels may play a role in the development of symptomatic CMV disease.

Prevention of CMV disease in pediatric kidney transplant recipients: evaluation of pp67 NASBA-based pre-emptive ganciclovir therapy combined with CMV hyperimmune globulin prophylaxis in high-risk patients

A new prevention strategy for CMV infection was evaluated in our pediatric kidney transplant unit. This approach comprises a pre-emptive therapy, based upon the monitoring of CMV pp67 mRNA in whole blood by the qualitative NASBA, combined with prophylactic CMV-IG in high risk (R-/D+) children. Thirty-one kidney transplant children were followed for six months with serial measurements of CMV pp67 mRNA in the blood. The R-/D+ patients were given prophylactic CMV-IG for the first 16 wk after transplantation. I.v. ganciclovir was administered upon CMV detection by NASBA and was discontinued after two consecutive negative results. CMV infection, detected by NASBA, developed in 11 (35%) recipients: one (33%) of the R+/D- patients and 10 (72%) of the R-/D+ patients. CMV disease developed in 9.6% of the patients (3/31), exclusively in the R-/D+ group. These three patients presented concurrently with CMV viremia and disease. It is noteworthy that two of the three patients could not receive a complete course of CMV-IG, and one of the latter two subjects had been treated for acute rejection 15 days before CMV infection. Ganciclovir was given for the 11 cases of primary infection, and for three cases of relapsed CMV infection. pp67 NASBA-based pre-emptive ganciclovir therapy, combined with prophylactic CMV-IG in high-risk patients leads to a lower rate of CMV disease, as long as a complete course of CMV-IG has been administered and ganciclovir is given during the period of treatment for acute rejection in high-risk populations.

Characterization of human cytomegalovirus uracil DNA glycosylase (UL114) and its interaction with polymerase processivity factor (UL44)

Here, we report the molecular characterization of the human cytomegalovirus uracil DNA glycosylase (UNG) UL114. Purified UL114 was shown to be a DNA glycosylase, which removes uracil from double-stranded and single-stranded DNA. However, kinetic analysis has shown that viral UNG removed uracil more slowly compared with the core form of human UNG (Delta84hUNG), which has a catalytic efficiency (k(cat)/K(M)) 350- to 650-fold higher than that of UL114. Furthermore, UL114 showed a maximum level of DNA glycosylase activity at equimolar concentrations of the viral polymerase processivity factor UL44. Next, UL114 was coprecipitated with DNA immobilized to magnetic beads only in the presence of UL44, suggesting that UL44 facilitated the loading of UL114 on DNA. Moreover, mutant analysis demonstrated that the C-terminal part of UL44 (residues 291-433) is important for the interplay with UL114. Immunofluorescence microscopy revealed that UL44 and UL114 colocalized in numerous small punctuate foci at the immediate-early (5 and 8 hpi) phases of infection and that these foci grew in size throughout the infection. Furthermore, coimmunoprecipitation assays with cellular extracts of infected cells confirmed that UL44 associated with UL114. Finally, the nuclear concentration of UL114 was estimated to be 5- to 10-fold higher than that of UL44 in infected cells, which indicated a UL44-independent role of UL114. In summary, our data have demonstrated a catalytically inefficient viral UNG that was highly enriched in viral replication foci, thus supporting an important role of UL114 in replication rather than repair of the viral genome.

Improvement in long-term renal graft survival due to CMV prophylaxis with oral ganciclovir: results of a randomized clinical trial

Oral ganciclovir prophylaxis and intravenous preemptive therapy are competitive approaches to prevent cytomegalovirus (CMV) disease after renal transplantation. This trial compared efficacy, safety and long-term graft outcome in 148 renal graft recipients randomized to ganciclovir prophylaxis (N = 74) or preemptive therapy (N = 74). Hierarchical testing revealed (i) patients with CMV infection had more severe periods of impaired graft function (creatinine clearance(max-min) 25.0 +/- 14.2 mL/min vs. 18.1 +/- 12.5 mL/min for patients without CMV infection; p = 0.02),(ii) prophylaxis reduced CMV infection by 65% (13 vs. 33 patients; p < 0.0001) but (iii) creatinine clearance at 12 months was comparable for both regimes (54.0 +/- 24.9 vs. 53.1 +/- 23.7 mL/min; p = 0.92). No major safety issues were observed, and patient survival at 12 months was similar in both groups (5 deaths [6.8%] vs. 4 [5.4%], p = 1.0000). Prophylaxis significantly increased long-term graft survival 4 years posttransplant (92.2% vs. 78.3%; p = 0.0425) with a number needed to treat of 7.19. Patients with donor +/recipient + CMV serostatus had the lowest rate of graft loss following prophylaxis (0.0% vs. 26.8%; p = 0.0035). In conclusion, it appears that routine oral prophylaxis may improve long-term graft survival for most renal transplant patients. Preemptive therapy can be considered in low risk patients in combination with adequate CMV monitoring.

Reduced incidence of new-onset posttransplantation diabetes mellitus during the last decade

BACKGROUND

A previous study (1995-1996) of 173 nondiabetic renal transplant recipients (historical cohort; HC) revealed a 20% incidence of new-onset posttransplantation diabetes mellitus (PTDM) and 32% with impaired glucose tolerance (IGT) or impaired fasting glucose (IFG). We examined whether glucose tolerance has improved after recent changes in our immunosuppressive protocol and a switch from deferred to preemptive cytomegalovirus (CMV) therapy.

METHODS

A total of 321 consecutive, nondiabetic patients (new cohort; NC) were examined 10 weeks after kidney transplantation with an oral glucose tolerance test (n=301) between January 2004 and December 2005.

RESULTS

Although recipients in the NC were on average 3 years older [mean (SD): 50.3 (14.6) vs. 47.4 (16.0), P=0.038] and had a higher mean body mass index [24.5 (3.6) vs. 23.5 (3.8) kg/m(2), P=0.003], a significantly lower incidence of both PTDM (13%) and IGT/IFG (18%) was observed in the NC (P<0.001) as compared to the HC. The patients in the NC received a significantly lower mean daily oral prednisolone dose [13.2 (4.7) vs. 15.3 (6.6) mg/day, P<0.001], and had lower frequencies of rejections (36% vs. 57%, P<0.001) and CMV infection (54% vs. 63%, P=0.071). Patients in the NC had significantly lower odds of developing PTDM, even after adjustment for age, prednisolone dose, HLA-B27 status and CMV infection (odds ratio: 0.42, 95% CI: 0.23-0.77, P=0.005).

CONCLUSIONS

The odds of developing PTDM are more than halved over the last decade. Possible explanations are changes in immunosuppressive therapy, fewer rejections, and lower doses of steroids.

The use of consensus guidelines for management of cytomegalovirus infection in renal transplantation

Cytomegalovirus (CMV) infection imposes a significant economic burden on susceptible patients after renal transplantation. Our study was conducted to determine the prediction, probability, consequences, and treatment costs of CMV infection under Canadian consensus guidelines in 270 sequential transplant patients. Transplant patients from donors positive (D(+)) for CMV into recipients negative (R(-)) for CMV received antiviral prophylaxis for 14 weeks and all but donor negative (D(-))/R(-) patients were monitored weekly for the CMVpp65 marker expression. Marker-positive patients and patients with CMV infection or disease received antiviral treatment. Within the first 6 months, 27% of the 270 patients tested had incidences of asymptomatic CMV infection, while 9% had CMV syndrome or disease. Only 1% of patients had infection after 6 months. The CMVpp65 marker levels were significantly greater in patients with syndrome or disease; but post-test probabilities and predictive value of the marker assay were low. Mean direct costs for care were $2256 and ranged from $927 for D(-)/R(-) patients to $7069 in the D(+)/R(-) patients. Extension of antiviral prophylaxis to D(+) or D(+)/R(+) patients significantly increased the estimated mean costs for an absolute reduction to 4% in CMV syndrome or disease. Our studies show that current guidelines for treatment enable effective control of CMV infection; however, alternative strategies have different economic impact.

The use of sirolimus in ganciclovir-resistant cytomegalovirus infections in renal transplant recipients

BACKGROUND

The widespread use of prophylactic ganciclovir and anti-lymphocyte/thymocyte therapies are associated with increased induction of ganciclovir-resistant cytomegalovirus (CMV) strains. The use of sirolimus has been associated with a lower incidence of CMV infection in transplant recipients. We questioned whether it could also be effective as a therapeutic treatment of resistant CMV infection.

METHODS

Patients with ganciclovir-resistant CMV infections determined clinically and by DNA sequencing analysis were enrolled. Antigenaemia and DNA sequencing were used to diagnosis and follow the mutations.

RESULTS

Nine transplant patients were given sirolimus plus mycophenolate mofetil (n = 4) or a calcineurin inhibitor (n = 5). Seven out of nine recipients were CMV IgG negative before transplantation. We observed a rapid decrease in antigenaemia levels, reaching zero in eight out of nine (88.9%) patients within a median of 20.3 +/- 10.1 d. Graft function remained stable and no patient presented acute rejection or recurrence of the CMV infection.

CONCLUSIONS

This suggests that the use of sirolimus plus ganciclovir therapy could be useful in ganciclovir-resistant CMV infections.

Oral valganciclovir is noninferior to intravenous ganciclovir for the treatment of cytomegalovirus disease in solid organ transplant recipients

Intravenous ganciclovir is the standard treatment for cytomegalovirus disease in solid organ transplant recipients. Oral valganciclovir is a more convenient alternative. In a randomized, international trial, recipients with cytomegalovirus disease were treated with either 900 mg oral valganciclovir or 5 mg/kg i.v. ganciclovir twice daily for 21 days, followed by 900 mg daily valganciclovir for 28 days. A total of 321 patients were evaluated (valganciclovir [n = 164]; i.v. ganciclovir [n = 157]). The success rate of viremia eradication at Day 21 was 45.1% for valganciclovir and 48.4% for ganciclovir (95% CI -14.0% to +8.0%), and at Day 49; 67.1% and 70.1%, respectively (p = NS). Treatment success, as assessed by investigators, was 77.4% versus 80.3% at Day 21 and 85.4% versus 84.1% at Day 49 (p = NS). Baseline viral loads were not different between groups and decreased exponentially with similar half-lives and median time to eradication (21 vs. 19 days, p = 0.076). Side-effects and discontinuations of assigned treatment (18 of 321 patients) were comparable. Oral valganciclovir shows comparable safety and is not inferior to i.v. ganciclovir for treatment of cytomegalovirus disease in organ transplant recipients and provides a simpler treatment strategy, but care should be taken in extrapolating to organ transplant recipients not properly represented in the present study.

Etiology and impact of cytomegalovirus disease on solid organ transplant recipients

PURPOSE

The characteristics, etiology, natural history, and direct and indirect effects of CMV disease in solid organ transplant recipients are described.

SUMMARY

CMV is a common herpesvirus that may be present in the donor or recipient of a solid organ transplant. Even though it is rarely pathogenic in healthy patients, transplant recipients are at risk for CMV viremia and symptomatic disease due to their immune-suppressed status. In addition to symptoms directly attributed to active disease, CMV can have a variety of indirect effects. Indirect effects may include additional infectious complications, posttransplant lymphoproliferative disease, allograft rejection, allograft loss, or death. The three most prevalent risk factors for CMV infection are CMV seronegativity in a recipient of an organ from a CMV-seropositive donor, the type of organ transplanted, and the degree of immune suppression. CMV prophylaxis is effective at preventing disease, but may result in a delayed onset where CMV disease occurs once the prophylaxis is stopped.

CONCLUSION

Knowledge of risk factors for CMV infection and disease, the natural history in transplant recipients, and its direct and indirect effects will help clinicians make appropriate decisions regarding the use of preventive strategies.

Association of the Outcome of Renal Transplantation with Antibody Response to Cytomegalovirus Strain--Specific Glycoprotein H Epitopes

BACKGROUND

Cytomegalovirus (CMV) is the most important pathogen affecting the outcome of renal transplantation. The combination of CMV-seronegative transplant recipients with CMV-seropositive transplant donors places recipients at the highest risk of CMV disease. In cases of congenital CMV infection, existing immunity only partially protected mothers from reinfection with a different genotypic strain. The effect of differences in infected CMV strains between CMV-seropositive transplant donors and CMV seropositive transplant recipients on the outcome of transplantation remains unclear.

METHODS

In this prospective multicenter study, the presence of antibodies against strain-specific glycoprotein H epitopes in 84 CMV-seropositive transplant donor/CMV-seropositive transplant recipient renal transplantation cases were determined, and their relationships to acute transplant rejection, CMV infection, degree of antigenemia, and CMV disease were evaluated.

RESULTS

Among the 84 donor/recipient pairs, 45 and 32 had matched and mismatched strain-specific glycoprotein H antibodies, respectively. Acute transplant rejection in the mismatched group was more frequent than it was in the matched group (63% vs. 22%; P=.005). CMV disease was also more frequently observed in the mismatched group (28% vs. 9%; P=.026). The mismatched group had a higher level of antigenemia (P=.019).

CONCLUSIONS

Our results illustrate more adverse events in the cases with a CMV-seropositive transplant donor and a CMV-seropositive transplant recipient in which the glycoprotein H antibodies are mismatched, suggesting that reinfection with a different CMV strain results in more complications.

Cytomegalovirus infection in renal transplant recipients is associated with impaired survival irrespective of expected mortality risk

Cytomegalovirus (CMV) infection and CMV disease are associated with increased mortality post-transplantation. We have thus retrospectively examined whether this association is found both in patients with high and low mortality risk. Between 1994 and 1997, 471 kidney transplant recipients were monitored once weekly for CMV pp65 antigenemia and CMV disease the first 100 d after tx and followed prospectively for median 66.6 months. Patients with nephrosclerosis, diabetic nephropathy and amyloidosis were selected as high mortality risk groups (HRG). Overall and cardiovascular mortality beyond 100 d in the low-risk group (n = 372) was 14% and 3.5%, and in the HRG (n = 99) 31% and 16%, respectively. The effects of CMV infection and disease, recipient age and gender, panel-reactive cytotoxic antibodies, acute rejection, HRG, and graft loss in the whole study period were tested on overall mortality beyond 100 d in multiple analysis. HRG was independently associated with overall mortality, RR = 2.03, and still both CMV infection and disease were significant risk factors for mortality, independent of HRG. The same analysis was repeated for HRG (n = 99). Even in this small group CMV disease was independently associated with overall mortality. These data indicate that CMV increase mortality independently both in patients with otherwise high- or low-risk for long-term mortality.

Infecciones en el paciente con trasplante renal y pancreático

Infection can lead to graft loss and death in patients undergoing kidney and double kidney-pancreas transplantation. In this review, the prophylactic measures, the post-transplant timeline for the development of infections, and the most frequent infectious complications in patients with kidney and pancreas transplantation are described. Although great advances have been achieved in the prevention of infections, new problems have developed. Nosocomial bacterial infection with multidrug-resistant bacteria is an emerging complication. Cytomegalovirus is still the most frequent viral infection despite the advances in prevention measures. Moreover, in recent years polyomavirus type BK infection has been recognized as a major cause of renal graft loss. Knowledge of the infectious complications associated with these transplants and the risk factors for their occurrence will allow optimal therapeutic management of this patient population.

Leukopenia Complicates Cytomegalovirus Prevention After Renal Transplantation With Alemtuzumab Induction

BACKGROUND

Cytomegalovirus (CMV) is a major cause of morbidity after transplantation. Valganciclovir (VGCV) is commonly utilized for CMV prophylaxis but can cause leukopenia, with risk compounded by the use of myelosuppressive immunosuppression. By utilizing a preemptive therapeutic strategy with VGCV targeted only toward patients at risk for developing CMV disease, the rate and extent of leukopenia may be reduced.

METHODS

VGCV prophylactic and preemptive strategies were compared in renal transplant recipients receiving alemtuzumab induction and prednisone-free maintenance with tacrolimus and mycophenolate mofetil (MMF). Patients were risk-stratified by CMV serologic status. All donor seropositive/recipient seronegative (D+/R-) patients, February 2002-January 2004 (n=32), received prophylaxis with VGCV 450 mg daily for 3 months. Outcomes of D+/-/R+ patients were compared. Patients in the first cohort, February 2002-October 2002 (n=61), received prophylaxis as described. In the second cohort, October 2002-January 2004 (n=110), patients were monitored by quantitative CMV-polymerase chain reaction (PCR) every 2 weeks for 3 months. If the CMV load was above laboratory threshold, VGCV 450 mg daily was initiated for 1 month or until viremia cleared.

RESULTS

Comparing preemptive therapy versus prophylaxis in D+/-/R+ patients, there was a lower incidence of leukopenia (67% vs. 82%, P=0.039) and trend toward less granulocyte-colony stimulating factor (G-CSF) use (24% vs. 33%, P=0.196), but higher CMV disease rate (15% vs. 3%, P=0.02). One limitation was strategy compliance: 41% (7 of 17) of preemptive patients who developed CMV missed at least 1 CMV-PCR before diagnosis. One-year patient (98.2% vs. 98.4%) and death-censored graft (100% vs. 98.4%) survival was similar.

CONCLUSIONS

Antiviral toxicity may be decreased with preemptive therapy, but effectiveness for CMV prevention seems dependent upon monitoring compliance.

Lymphocyte propagation from biopsies of kidney allografts

Morphological evaluation of transplant biopsies, usually using the Banff classification, is the most important tool to diagnose rejection after kidney transplantation. However, morphological analysis only scores the amount and localisation of infiltrating cells, and studies show that up to 30% of grafts with a stable function display infiltration of lymphocytes consistent with acute cellular rejection. Methods to study the functional properties of the infiltrating lymphocytes are therefore needed. We applied a tissue culture system on biopsies from transplanted human kidneys, allowing infiltrating cells to propagate out from the tissue. Cells were then counted and subtyped by flow cytometry. The results were correlated to morphology. In total, 92 biopsies from 69 patients were analysed. For 14 patients, serial biopsies were available. In grafts with cellular or combined cellular and vascular rejection, the number of ex vivo propagated mononuclear cells was higher than from non-rejecting grafts. A similar pattern was seen for CD3(+) T cells as well as for T cells expressing CD25 or MHC class II antigens. However, the proportion of CD25(+) or MHC class II(+) T lymphocytes was similar in all groups (no rejection, vascular rejection, borderline changes, cellular rejection, combined cellular and vascular rejection). In all groups the number of CD4(+) cells was higher than the number of CD8(+) cells. The results confirm previous experimental studies showing that graft-infiltrating cells are possible to culture in vitro and that lymphocyte propagation correlates to acute cellular rejection. Tissue culturing is easy to perform and evaluate and can be used to determine and analyse the cellular immune response to allografts and may thus be used as a complement to morphological analyses.

Cytomegalovirus infection in renal transplant recipients

We have retrospectively analyzed the incidence of cytomegalovirus (CMV) infection in 250 consecutive renal allograft transplants performed in 244 recipients. The mean follow-up was 35.1+/-25.4 months. Immunosuppression was cyclosporine- or tacrolimus-based triple therapy. CMV infection prophylaxis with ganciclovir for 3 months post transplant was prescribed in CMV-seronegative recipients of allografts from seropositive donors (D+R-) and in all recipients treated with OKT3. CMV antigenemia was monitored by the pp65-antigen assay. Thirteen of 57 D+R- recipients (22.8%) developed CMV antigenemia. One recipient had a breakthrough of CMV antigenemia during ganciclovir prophylaxis; 12 D+R- recipients developed CMV antigenemia 147.5+/-173.8 days after transplantation. Four of 13 (30.7%) D+R- recipients had asymptomatic CMV infection, 8 (61.6%) had CMV infection with non-specific symptoms including fever, and 1 (7.7%) developed CMV pneumonia. Six of 13 (46.1%) D+R- patients had been treated with intensified immunosuppressive therapy before CMV infection. In the low-risk CMV groups (D+R+; D-R+; D-R-), 28 recipients (14.5%) developed CMV antigenemia 42.5+/-15.2 days post transplantation. Ten of the 28 (35.7%) recipients had asymptomatic CMV infection, 17 (60.7%) developed CMV infection with non-specific symptoms, and 1 (3.6%) developed CMV pneumonia. Twenty-one of 28 (75.0%) had intensified immunosuppressive therapy before CMV infection. In conclusion, ganciclovir prophylaxis diminished and delayed the onset of CMV infection but did not totally prevent it from occurring in D+R- renal transplant recipients. Clinicians should be vigilant to the possibility of CMV infection in both seronegative and seropositive recipients, especially after anti-rejection therapy.

Determination of ganciclovir in different matrices from solid organ transplanted patients treated with a wide range of concomitant drugs

The aim of the present study was to develop a time-efficient chromatographic method for the analysis of therapeutic concentrations of ganciclovir (GCV) in plasma, urine as well as dialysate (from continuous renal replacement therapy) from solid organ transplant recipient treated with either GCV or its prodrug valganciclovir (VGCV) in combination with a wide variety of other concomitant drugs. Sample preparation was performed by reversed phase solid phase extraction and was followed by separation of the analytes on a reversed phase column using isocratic elution with a mobile phase consisting of acetonitrile-a counter ion (50 mM 1-heptanesulfonic acid) in an aqueous sodium dihydrogen phosphate buffer (pH 2.1; 10 mM) (10:90 v/v) and a fluorescence detector. Validation of the method showed linearity within the concentration range of 0.1-40 microg/mL for plasma and 0.1-120 microg/mL for urine and dialysate (R(2)>0.99, n> or =5). Accuracy and precision (evaluated at 0.1, 5 and 40 microg/mL) were both satisfactory. The LLOQ was determined to be 0.1 microg/mL. The method was successfully applied on clinical samples from renal transplant recipients treated with VGCV in combination with a variety of usually used concomitant drugs for solid organ transplant recipients.

Infections Complicating Solid Organ Transplantation

The requirements for immune suppression after solid organ transplantation increases the risk of infection with a myriad of organisms. There are many unique and evolving aspects of infection after solid organ transplantation. Advances in immunosuppressive therapy and improved protocols for infection prophylaxis have resulted in changes in the timing and clinical presentation of opportunistic infections. Vigilance in the diagnostic evaluation of suspected infection in the solid organ transplant recipient is essential. This article reviews the basic evaluation and treatment options for many of the infectious conditions peculiar to the immunosuppressed patient.