Cytomegalovirus Infection In Transplant Recipients Research Articles

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.

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

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 of 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 in clinical samples or indirectly through serology. Part I of this article reviews infections in immunocompromised patients and the various approaches to monitoring and laboratory diagnosis of CMV infection.

Management of Human Cytomegalovirus Infection in Transplant Recipients by the Pre-Emptive Therapy Approach

Human cytomegalovirus (HCMV) infections are still a major infectious complication in the post-transplant period of both solid organ transplant recipients (SOTRs) and hematopoietic stem cell transplant recipients (HSCTRs). For many years, the major diagnostic assay has been antigenemia, allowing semi-quantification of HCMV load in blood from transplanted patients with disseminated HCMV infection. More recently, the real-time PCR assay has replaced antigenemia for HCMV DNAemia quantification. Prevention of HCMV disease is based on either prophylaxis or pre-emptive therapy with antiviral drugs. The latter approach has been in use in our department for the last 15 years. A cut-off of 300,000 DNA copies/ml whole blood in SOTRs with either primary or reactivated infection, and a cut-off of 10,000 DNA copies/ml blood in HSCTRs proved to be safe and effective in prospective randomized, controlled trials. With this approach, HCMV disease is consistently prevented, except for a limited number of cases of organ localization in the absence of virus in blood. In these cases, HCMV infection/disease must be diagnosed by local biopsy samples.

Prophylaxis Versus Preemptive Therapy for Prevention of the Consequences of Cytomegalovirus Infection in Transplant Recipients: A Still Unresolved Issue

Prophylaxis Versus Preemptive Therapy for Prevention of the Consequences of Cytomegalovirus Infection in Transplant Recipients: A Still Unresolved Issue

Immunizations and infectious diseases in pediatric liver transplantation

Liver transplantation (LTx) is an established and effective treatment for children with end-stage and metabolic liver disease. Improved surgical techniques and immunosuppressive regimens have led to enhanced short-term and long-term survival rates, which now approach or exceed 90%. Consequently, more children are being referred for LTx, and an increasing numbers of pediatric centers routinely perform this procedure. Infectious complications are an important cause of morbidity and mortality in children undergoing LTx. However, improvements in immune suppression management along with the availability of new antimicrobial agents and diagnostic tools have resulted in improved treatment and preventative regimens, thus reducing the impact of infectious complications on these children. This review provides an overview of the infectious complications and prevention strategies for children undergoing LTx.

Antiviral strategies to combat cytomegalovirus infections in transplant recipients

Human cytomegalovirus remains an important pathogen for transplant recipients. To date, a limited number of drugs have been licensed for the treatment of HCMV infection and disease, all sharing the same target molecule, the viral DNA-polymerase. Although combating HCMV with DNA-polymerase inhibitors is effective and has been established for many years, there are several drawbacks associated with the use of these drugs including toxicity and emergence of drug resistance. In order to overcome these problems different treatment options and durations have been assessed and new and improved antiviral drugs with novel molecular targets have been discovered. However, not all of these novel drugs had the properties for success in clinical development, and alternative treatment options with known drugs have been evaluated in parallel. Today the need for an antiviral drug that is potent, safe and well tolerated remains.

Monitoring human cytomegalovirus infection in transplant recipients

Human cytomegalovirus (HCMV) infection remains one of the most challenging infectious complications in both solid organ transplant (SOT) and hemopoietic stem cell transplant (HSCT) recipients. In the last two decades advances have been made in the diagnosis and monitoring of HCMV infection in SOT and HSCT recipients following introduction of quantitative assays such as rapid virus isolation in blood (viremia), quantitation of pp65 in peripheral blood leukocytes (antigenemia), and quantitation of viral genome in blood (DNAemia). The availability of these rapid diagnostic assays has allowed treatment administration during the presymptomatic phase of HCMV infection (preemptive treatment) and greatly reduced HCMV-related morbidity and mortality, particularly among HSCT recipients. Definition of clinically validated thresholds for initiating preemptive treatment in SOT and HSCT recipients is a major goal in the transplantation setting. With respect to universal prophylaxis of HCMV infection in transplant recipients, the preemptive treatment approach shows advantages in (i) treating a lower number of patients for shorter periods of time and (ii) avoiding the reported emergence of HCMV disease after interruption of anti-HCMV prophylaxis. To understand the mechanism behind long-term control of HCMV infection in transplant recipients, the HCMV-specific T-cell response must be evaluated.

Update from the 7th annual meeting of the Italian society of virology

The Italian Society of Virology (SIV) held a meeting in Orvieto (June 24-26, 2007) aimed at promoting interactions and collaborations between scientists in the field of Virology. The meeting had an attendance of about 170 virologists from Italy. In accordance with the normal format of the SIV National Meeting the conference transcended all areas of Virology. Sessions included invited speakers together with selected oral presentation. Covered topics included: General Virology and Viral Genetics, Medical Virology and Antiviral Therapy, Viral Biotechnologies and Gene Therapy, Viral Oncogenesis and Vaccines, Virus-Host Interactions and Pathogenesis, Emerging and Zoonotic Viral Infections. In this edition, a special effort was addressed to the HPV infection and prevention and to the guidelines for the preemptive (presymptomatic) therapy of human cytomegalovirus infections in transplant recipients. A summary of the main topics are reported.

Impairment of cytomegalovirus-specific cellular immune response as a risk factor for cytomegalovirus disease in transplant recipients

Human cytomegalovirus (CMV) infection is common in most people but nearly asymptomatic in immunocompetent individuals. After primary infection the virus persists throughout life in a latent form in a variety of tissues, particularly in precursor cells of the monocytic lineage. CMV reinfection and occurrence of disease are associated with immunosuppressive conditions. Solid organ and bone marrow transplant patients are at high risk for CMV disease as they undergo immunosuppression. Antiviral treatment is effective in controlling viremia, but 10-15% of infected patients can experience CMV disease by the time the drug is withdrawn. In addition, long-term antiviral treatment leads to bone marrow ablation and renal toxicity. Furthermore, control of chronic CMV infection in transplant recipients appears to be dependent on the proper recovery of cellular immunity. Recent advances in the characterization of T-cell functions and identification of distinct functional signatures of T-cell viral responses have opened new perspectives for monitoring transplant individuals at risk of developing CMV disease.

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

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

Cytomegalovirus in transplantation – challenging the status quo

Cytomegalovirus (CMV) infection of solid organ transplant (SOT) recipients causes both ''direct'' and ''indirect'' effects including allograft rejection, decreased graft and patient survival, and predisposition to opportunistic infections and malignancies. Options for CMV prevention include pre-emptive therapy, whereby anti-CMV agents are administered based on sensitive viral assays, or universal prophylaxis of all at-risk patients. Each approach has advantages and disadvantages in terms of efficacy, costs, and side effects. Standards of care for prophylaxis have not been established. A committee of international experts was convened to review the available data regarding CMV prophylaxis and to compare preventative strategies for CMV after transplantation from seropositive donors or in seropositive recipients. Pre-emptive therapy requires frequent monitoring with subsequent treatment of disease and associated costs, while universal prophylaxis results in greater exposure to potential toxicities and costs of drugs. The advantages of prophylaxis include suppressing asymptomatic viremia and prevention of both direct and indirect effects of CMV infection. Meta analyses reveal decreased in mortality for patients receiving CMV prophylaxis. Costs associated with prophylaxis are less than for routine monitoring and pre-emptive therapy. The optimal duration of antiviral prophylaxis remains undefined. Extended prophylaxis may improve clinical outcomes in the highest-risk patient populations including donor-seropositive/recipient-seronegative renal transplants and in CMV-infected lung and heart transplantation. Prophylaxis is beneficial in preventing direct and indirect effects of CMV infection in transplant recipients, affecting both allograft and patient survival. More studies are necessary to define optimal prophylaxis regimens.

Clinical and Immunologic Aspects of Cytomegalovirus Infection in Solid Organ Transplant Recipients

Primary cytomegalovirus (CMV) infection is a major cause of morbidity and mortality in recipients after solid organ transplantation (SOT). Widespread and prolonged use of antiviral drugs has changed the natural course of CMV disease by delaying its onset and causing drug resistance. CMV induces a strong cellular immune response, even in immunosuppressed patients, and has developed strategies to evade this immune surveillance. This review summarizes challenges in managing CMV infection in transplant recipients and highlights current insights in the cellular immune response against CMV.

Cytomegalovirus infection in transplant recipients resolves when circulating gammadelta T lymphocytes expand, suggesting a protective antiviral role.

gammadelta T cells undergo massive expansion in the peripheral blood of renal transplant recipients who are infected with cytomegalovirus (CMV). In a 3-year prospective study, the relationship between the evolution of CMV infection and the kinetics of gammadelta T cell amplification was followed for 10 months after transplantation. Patients with late gammadelta T cell expansion (>/=45 days) had significantly longer (P<.0001) and higher (P<.0003) pp65 antigenemia and more-symptomatic CMV disease than did patients with early expansion. Analysis of data for each patient showed that gammadelta T cell expansion is concomitant with the resolution of CMV infection and disease, regardless of the CMV serologic status of donor and recipient before transplantation. These observations point to gammadelta T cell percentage determination as a new, rapid, and reliable prognosis factor to predict the resolution of CMV infection and strongly suggest that gammadelta T cells play a protective role against CMV infection.

Diagnosis and monitoring of human cytomegalovirus infection in transplant recipients

Diagnosis and monitoring of human cytomegalovirus infection in transplant recipients

Cytomegalovirus-induced allograft vascular disease

A wealth of clinical and experimental evidence exists indicating the interaction of cytomegalovirus (CMV) infection and rejection in cardiac allografts. Acute inflammatory response after transplantation leads to release of proinflammatory cytokines that may activate latent CMV infection. In a reciprocal situation, CMV infection leads to up-regulation of transplant antigens and, thereby, to increased immunogenicity and acute rejection. The activation of intragraft mononuclear inflammatory cells and increased mRNA expression of various cytokines and growth factors results in acceleration of the development of chronic rejection. Thus, the effect of CMV infection on cardiac allograft dysfunction is bidirectional and biphasic. These two effects of CMV on allograft dysfunction emphasize the need for precise diagnosis of CMV infection in transplant recipients and pre-emptive or prophylactic antiviral therapy. The benefits of this strategy may be evident not only during the early post-transplant period but also, in particular, 5 to 10 years after transplantation as better graft survival.

Sensitive detection of cytomegalovirus infection in transplant recipients using nucleic acid sequence-based amplification

THE MAJORITY of the adult human population is seropositive for cytomegalovirus (CMV), a member of the b-herpesvirus family. Normally, infection of immunocompetent individuals does not cause disease. In contrast, infection of immunocompromised individuals, such as patients with AIDS and transplant recipients, can cause severe complications and can even lead to death. Therefore, early detection of active CMV infection is necessary to start effective antiviral treatment. Nucleic Acid Sequence-Based Amplification (NASBA) has been developed for the specific amplification of RNA. In previous studies, we evaluated the diagnostic value of monitoring the expression of the CMV immediate early (IE) 1 and late pp67 mRNA using NASBA, in peripheral blood cells of kidney transplant (Tx) patients. The IE 1 mRNA is expressed directly after entrance of the virus into a cell, while pp67 mRNA is expressed in a late stage in the replication cycle. NASBA results were compared to the techniques that are routinely being used for the detection of CMV: pp65-antigenemia, virus culture, and serology. From this study it was concluded that IE NASBA is a very sensitive assay that detects the onset of CMV infection significantly earlier than the other assays. This is especially valuable for patients that are at risk for symptomatic CMV infection, i.e., seronegative patients with an organ of a seropositive donor and/or intense immunesuppression. The sensitivity and specificity values of pp67 NASBA were comparable to those of the antigenemia assay. We set up a similar study to evaluate the diagnostic value of IE and pp67 NASBA for liver Tx patients. The liver Tx patients are usually severely ill, immunesuppression is more intense compared to the kidney Tx patients and they often have anti-rejection therapy. The results for IE NASBA are presented in this report. The evaluation of pp67 NASBA is still in progress.

Cytomegalovirus infection and cardiac allograft vasculopathy

There is a wealth of clinical and experimental evidence indicating the interaction of cytomegalovirus (CMV) infection and rejection in cardiac and other solid organ allografts. A plausible explanation for this association comes from data showing that therapy with biologicals, sepsis, and rejection, all lead to the release of TNF-alpha which, upon binding to its receptor, activates NF-kB. TNF-alpha is also able to stimulate the activity of the CMV-IE enhancer/promoter region. CMV infection of several cell lines leads to NF-kB activation. NF-kB binding sites are present in regulatory regions of various cellular and viral genes, including the IE enhancer region of CMV. In a reciprocal situation, CMV infection, most likely via gamma-interferon, leads to upregulation of MHC antigens in the transplant and, thereby, to increased transplant immunogenicity. Thus, a vicious circle is induced. We have investigated in detail the pathobiology of CMV and allograft vasculopathy (chronic rejection) in experimental animals, using aortic and cardiac allografts as well as a trachea model. The results may be summarized as follows: Infection of the recipient with rat CMV results in an early inflammatory response in the aortic and cardiac allograft vascular adventitia and intima (endothelialitis) and in the airway wall of tracheal allografts. This early inflammatory response leads to enhanced intimal thickness in aortic and cardiac allografts and enhanced luminal occlusion of tracheal allografts. Timewise, this coincides with early activation of intragraft inflammatory leukocytes and increased mRNA of various growth factors and cytokines. When the recipients receive gancyclovir, the enhanced intimal response in aortic and cardiac allografts and luminal occlusion in tracheal allografts is entirely abolished. Gancyclovir treatment dramatically reduces the inflammatory response in the allograft, and thereby growth factor synthesis in response to injury. However, gancyclovir does not prevent the expression of IE antigen of CMV, suggested to inactivate tumor suppressor protein p53 predisposing smooth muscle cells to increased growth. Taken together, the effect of CMV infection on cardiac allograft dysfunction is bidirectional and biphasic. The bidirectional nature emerges from the observations that acute CMV infection may accelerate acute rejection, and, on the other hand, acute alloimmune response-associated cytokine response may activate latent CMV infection. The biphasic effect of CMV on allograft dysfunction refers to its early and late detrimental effects, i.e. during the time of acute and chronic rejection. These two effects of CMV on allograft dysfunction emphasize the need for precise diagnosis of CMV infection in transplant recipients and pre-emptive or prophylactic anti-viral therapy. The benefits of this strategy may not be evident during the early post-transplant period, but 5-10 years after transplantation they manifest as better graft survival.

Nucleic acid sequence-based amplification: a new technique for monitoring cytomegalovirus infection in transplant recipients

HE MAJORITY of the adult human population is infected with cytomegalovirus (CMV), a member of the b-herpesvirus family. Normally, infection of immunocompetent individuals does not cause disease. In contrast, infection of immunocompromised individuals, such as neonates, patients with AIDS, and transplant recipients, can cause severe complications and can even lead to death. Therefore, early detection of active CMV infection is necessary to start effective antiviral treatment. Nucleic acid sequence-based amplification (NASBA) has been developed for the specific amplification of RNA. 1 We evaluated the diagnostic value of monitoring the expression of the CMV immediate early (IE) 1 mRNA using NASBA, in peripheral blood cells of kidney and liver transplant patients. The IE 1 mRNA is expressed directly after entrance of the virus into a cell. NASBA results were compared to the techniques which are routinely being used for the detection of CMV: pp65-antigenemia, virus culture, and serology.

CMV Infection of transplant Recipients

C YTOMEGALOVIRUS (CMV) LlSUdly CiXlSeS ZiSyIllptOmatic or clinically insignificant infection in the immunocompetent host. Thereafter, the virus persists in a latent state, but may be reactivated by immunosuppression. Reactivation of latent infection most commonly occurs in the context of Human Immunodeficiency Virus (HIV) infection and allogeneic organ transplantation, but has also been described in other settings. Chronic liver disease may be associated with reactivation of CMV. Tanaka et al. detected CMV DNA by polymerase chain reaction (PCR) in the blood of 77/122 (63.1%) patients with hepatic cirrhosis, but only l/40 normal controls was PCR-positive (1). In the same study, PCR-positive patients with cirrhosis were antigenaemia assay-negative (the antigenaemia assay employs immunological methods to detect CMV-encoded antigens in peripheral blood smears). In cirrhotic patients, PCR-positivity was associated with worse liver dysfunction and with greater suppression of cellular immune responses. Using PCR, CMV DNA has also been detected in the blood of 23/25 septic patients on an Intensive Care Unit (ICU), but not in controls (2). Despite virological evidence of CMV reactivation in these patient groups (cirrhotic patients and septic patients), symptomatic infection did not develop. This suggests that other factors are required for the development of CMV-associated disease. Donor virus is clearly the most important factor. Symptomatic infection of transplant recipients is usually associated with donor seropositivity, and is a consequence of the acquisition of donor CMV strain in the context of immunosuppression. When the recipient is seronega-

Cytomegalovirus antigenemia: clinical correlations in transplant recipients and in persons with AIDS

We evaluated a rapid immunoperoxidase technique for the detection of cytomegalovirus (CMV) antigenemia in peripheral blood neutrophils of 56 transplant recipients (117 specimens) and 36 persons with AIDS (59 specimens). Antigenemia was 92% sensitive and 98% specific for the detection of clinical CMV infection in transplant recipients and 100% sensitive and 86% specific in persons with AIDS. Overall, CMV antigenemia was a more rapid and sensitive method for the detection of clinical CMV infection than either shell vial culture or conventional tube culture of blood.