Reactivation of Viruses in Solid Organ Transplant Patients Receiving Cytomegalovirus Prophylaxis

Targeting CMV Reactivation to Optimize Care for Critically Ill COVID-19 Patients: A Review on the Therapeutic Potential of Antiviral Treatment

Cytomegalovirus (CMV) reactivation has been linked to adverse clinical outcomes in critically ill patients, with emerging evidence suggesting a potential connection with severe COVID-19. Mechanisms driving this association may include primary lung injury, amplification of systemic inflammation, and secondary immunosuppression. Diagnostic challenges in detecting and assessing CMV reactivation necessitate a comprehensive approach to improve accuracy and inform treatment decisions. Currently, there is limited evidence on the efficacy and safety of CMV pharmacotherapy in critically ill COVID-19 patients. Although insights from non-COVID-19 critical illness studies suggest a potential role for antiviral treatment or prophylaxis, the risks and benefits must be carefully balanced in this vulnerable patient population. Understanding the pathophysiological role of CMV in the context of COVID-19 and exploring the advantages of antiviral treatment are crucial for optimizing care in critically ill patients. This review provides a comprehensive synthesis of available evidence, emphasizing the need for additional investigation to establish the role of CMV treatment or prophylaxis in the management of severe COVID-19 and to develop a framework for future research on this topic.

Infections after organ transplantation and immune response

Organ transplantation has provided another chance of survival for end-stage organ failure patients. Yet, transplant rejection is still a main challenging factor. Immunosuppressive drugs have been used to avoid rejection and suppress the immune response against allografts. Thus, immunosuppressants increase the risk of infection in immunocompromised organ transplant recipients. The infection risk reflects the relationship between the nature and severity of immunosuppression and infectious diseases. Furthermore, immunosuppressants show an immunological impact on the genetics of innate and adaptive immune responses. This effect usually reactivates the post-transplant infection in the donor and recipient tissues since T-cell activation has a substantial role in allograft rejection. Meanwhile, different infections have been found to activate the T-cells into CD₄⁺ helper T-cell subset and CD₈⁺ cytotoxic T-lymphocyte that affect the infection and the allograft. Therefore, the best management and preventive strategies of immunosuppression, antimicrobial prophylaxis, and intensive medical care are required for successful organ transplantation. This review addresses the activation of immune responses against different infections in immunocompromised individuals after organ transplantation.

Cytomegalovirus and other herpesviruses after hematopoietic cell and solid organ transplantation: From antiviral drugs to virus-specific T cells

Herpesviruses can either cause primary infection or may get reactivated after both hematopoietic cell and solid organ transplantations. In general, viral infections increase post-transplant morbidity and mortality. Prophylactic, preemptive, or therapeutically administered antiviral drugs may be associated with serious side effects and may induce viral resistance. Virus-specific T cells represent a valuable addition to antiviral treatment, with high rates of response and minimal side effects. Even low numbers of virus-specific T cells manufactured by direct selection methods can reconstitute virus-specific immunity after transplantation and control viral replication. Virus-specific T cells belong to the advanced therapy medicinal products, and their production is regulated by appropriate legislation; also, strict safety regulations are required to minimize their side effects.

Incidence of herpes zoster in adult solid organ transplant recipients: A meta-analysis and comprehensive review

BACKGROUND

Chronic immunosuppressive therapy in solid organ transplant (SOT) recipients can trigger latent varicella zoster virus reactivation even in those with stable graft function. The inactivated herpes zoster (HZ) vaccine can be effective in preventing post-transplant HZ, which can cause severe neuralgia or disseminated disease. This meta-analysis aims to assess the incidences of HZ across transplant organs in SOT recipients.

METHODS

We included 12 observational studies (6560 recipients) from a PubMed and EMBASE search of articles through October 2019 and collected data from single-center dating from January 2001 to December 2017 (3498 recipients). The pooled HZ incidence and its differences between subgroups were obtained from random-effect models and meta-analysis of variance tests using R package.

RESULTS

The overall pooled crude incidence was 9.1% (95% confidence interval [CI], 7.6%-10.8%). The pooled incidence was similar between sexes but significantly different between transplanted organs (P < .001). Heart transplants (HT) (n = 644) have the highest pooled incidence with 15.2% (95% CI, 12.7%-18.2%), followed by lung transplants (LTX) (n = 780) with 11.0% (8.3%-14.4%). Kidney transplants (n = 5435) have the lowest incidence of 6.7 (5.1%-8.8%). The meta-regression analysis revealed that HZ development had a relationship with past graft rejection (P = .024).

CONCLUSION

These data support the need for subunit HZ vaccination in SOT recipients with a high risk for HZ, especially HT and LTX recipients, without respect to the late post-transplant period.

Post-allogeneic hematopoietic stem cell transplantation viral reactivations and viremias: a focused review on human herpesvirus-6, BK virus and adenovirus

Human cytomegalovirus and Epstein-Barr virus have been recognized as potential drivers of morbidity and mortality of patients undergoing allogeneic stem cell transplantation for years. Specific protocols for monitoring, prophylaxis and pre-emptive therapy are in place in many transplant settings. In this review, we focus on the next three most frequent viruses, human herpesvirus-6, BK virus and adenovirus, causing reactivation and/or viremia after allogeneic transplant, which are increasingly detected in patients in the post-transplant period owing to emerging techniques of molecular biology, recipients' characteristics, treatment modalities used for conditioning and factors related donors or stem cell source. Given the less frequent detection of an illness related to these viruses, there are often no specific protocols in place for the management of affected patients. While some patients develop significant morbidity (generally older), others may not need therapy at all (generally younger or children). Furthermore, some of the antiviral therapies used are potentially toxic. With the addition of increased risk of secondary infections, risk of graft failure or increased risk of graft-versus-host disease as well as the relationship with other post-transplant complications, the outcomes of patients with these viremias remain unsatisfactory and even long-term survivors experience increased morbidity.

Human Herpesvirus 7-Related Acute Encephalopathy with Biphasic Seizures and Late Reduced Diffusion

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a recently described entity so far exclusively in East Asian children. AESD diagnosis is based on clinicoradiologic criteria, often without pleocytic CSF and characterized by hyperglycemia and transaminasemia. Here, we present the first case of human herpesvirus 7-related AESD in an immunocompetent child >2 years old and of Caucasian origin.

Analysis of Ganciclovir-Resistant Cytomegalovirus Infection Caused by the UL97 Gene Mutation in Codons 460 and 520 in Pediatric Patients: A Case Series

Background

Drug-resistant cytomegalovirus (CMV) infection has been increasingly recognized. However, there are limited data in pediatric patients. In this study, the prevalence and factors associated with CMV infection with UL97 mutations in pediatric patients treated with ganciclovir but not responding to treatment were evaluated.

Methods

This retrospective study was conducted from January 2013 to December 2017. All patients who were suspected of having ganciclovir-resistant CMV infection and had never had ganciclovir prophylaxis were included. Genotypic assay for UL97 mutations in codons 460 and 520 conferring ganciclovir resistance was performed. Factors associated with the presence of UL97 mutations were analyzed.

Results

Of 34 patients included, 10 patients (29.4%) had a genotypically confirmed UL97 mutation. The median age (interquartile range [IQR]) was 3 (0.85–8.68) years. Ganciclovir resistance was tested at a median time (IQR) of 22.5 (14.3–31) days after initiation of ganciclovir. All resistant isolates harbored a UL97 mutation in codon 460. Compared with patients infected with CMV without UL97 mutation, those infected with UL97 mutation strains were younger (median age [IQR], 3.02 [0.85–8.68] vs 10.45 [2.7–16.4] years) and had a higher maximum viral load (median [IQR], 5.06 [4.74–6.05] vs 4.42 [4.03–4.87] copies/mL). Six of 10 (60%) patients were successfully treated with high-dose ganciclovir (7.5 mg/kg twice daily).

Conclusions

UL97 mutation ganciclovir-resistant CMV infection was not uncommon in the pediatric population. Screening for this mutation should be considered in patients experiencing virological worsening while ganciclovir is given, even if patients have not previously received ganciclovir prophylaxis.

Varicella zoster virus in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the American Society of Transplantation Infectious Diseases Community of Practice review the diagnosis, prevention, and management of varicella zoster virus (VZV) in the pre- and post-transplant period. Primary varicella is an uncommon complication post-solid-organ transplant (SOT), except among pediatric transplant patients and those seronegative for VZV. As the majority of SOT recipients are seropositive for VZV, herpes zoster (HZ) occurs frequently following SOT, particularly among recipients who are older (≥65 years of age) and those receiving more intensive immunosuppression. Transplant providers should aware of the increased risk for HZ-related complications such as dissemination, organ-specific involvement, and post-herpetic neuralgia. Treatment for localized zoster is primarily given as oral regimens, but those with more complicated presentations or those at risk for dissemination should be treated initially with IV therapy. Available antiviral prophylaxis regimens and vaccination strategies for varicella and HZ among these immunosuppressed patients remain a mainstay for prevention in the pre-and post-transplant periods. Finally, we discuss important approaches to addressing post-exposure prophylaxis and infection control practices for those SOT patients with documented VZV infections.

Infection in Kidney Transplant Recipients

In organ transplant recipients, impaired inflammatory responses suppress the clinical and radiologic findings of infection. The possible etiologies of infection are diverse, ranging from common bacterial and viral pathogens that affect the entire community to opportunistic pathogens that cause invasive disease only in immunocompromised hosts. Antimicrobial therapies required to treat established infection are often complex, with accompanying risks for drug toxicities and drug interactions with the immunosuppressive agents used to maintain graft function. Rapid and specific diagnosis is essential for successful therapy. The risk of serious infections in the organ transplant patient is largely determined by the interaction between two factors: the patient’s epidemiologic exposures and the patient’s net state of immunosuppression. The epidemiology of infection includes environmental exposures and nosocomial infections, organisms derived from donor tissues, and latent infections from the recipient activated with immunosuppression. The net state of immune suppression is a conceptual framework that measures those factors contributing to risk for infection: the dose, duration, and temporal sequence of immunosuppressive drugs; the presence of foreign bodies or injuries to mucocutaneous barriers; neutropenia; metabolic abnormalities including diabetes; devitalized tissues, hematomas, or effusions postsurgery; and infection with immunomodulating viruses. Multiple factors are present in each host. A timeline exists to aid in the development of a differential diagnosis for infection. The timeline for each patient is altered by changes in prophylaxis and immunosuppressive drugs. For common infections, new microbiologic assays, often nucleic acid based, are useful in the diagnosis and management of opportunistic infections.

Common viral infections in kidney transplant recipients

Infectious complications have been considered as a major cause of morbidity and mortality after kidney transplantation, especially in the Asian population. Therefore, prevention, early detection, and prompt treatment of such infections are crucial in kidney transplant recipients. Among all infectious complications, viruses are considered to be the most common agents because of their abundance, infectivity, and latency ability. Herpes simplex virus, varicella zoster virus, Epstein-Barr virus, cytomegalovirus, hepatitis B virus, BK polyomavirus, and adenovirus are well-known etiologic agents of viral infections in kidney transplant patients worldwide because of their wide range of distribution. As DNA viruses, they are able to reactivate after affected patients receive immunosuppressive agents. These DNA viruses can cause systemic diseases or allograft dysfunction, especially in the first six months after transplantation. Pretransplant evaluation and immunization as well as appropriate prophylaxis and preemptive approaches after transplant have been established in the guidelines and are used effectively to reduce the incidence of these viral infections. This review will describe the etiology, diagnosis, prevention, and treatment of viral infections that commonly affect kidney transplant recipients.

Immune Monitoring of Infectious Complications in Transplant Patients: an Important Step towards Improved Clinical Management

Immune reconstitution following organ transplantation is absolutely critical in preventing infectious complications. However, understanding the kinetics of immune reconstitution and its potential impact on the clinical management of transplant patients remains a significant challenge. Over the last decade, various platform technologies have emerged which have provided important insights into the immune reconstitution kinetics in transplant patients. However, many of these technologies are too complicated and cumbersome to implement in a clinical setting. In this issue of the Journal of Clinical Microbiology, Chiereghin et al. (J. Clin. Microbiol. 56:e01040-17, 2018, https://doi.org/10.1128/JCM.01040-17) report the results of their evaluation of the QuantiFERON-CMV (QFN-CMV) assay to assess human cytomegalovirus (CMV)-specific CD8⁺ T-cell immunity in heart transplant recipients as a prognostic tool. These studies showed that patients with absence of global immune reactivity in the QFN-CMV assay were at a higher risk of developing CMV after discontinuing antiviral prophylaxis. Furthermore, failure to reconstitute CMV-specific immunity after resolution of the first episode of viremia was associated with viral relapse. These observations, along with other recent clinical studies utilizing the QFN-CMV assay, demonstrate that systematic monitoring of antiviral immunity can be successfully used as a prognostic tool and also to guide changes to the clinical management of transplant patients.

Severe Hepatitis C Recurrence as a Risk Factor for Opportunistic Infections in Liver Transplant Recipients

OBJECTIVE

The aim of the study was to determine the clinical characteristics, frequency of opportunistic infections (OI), and the outcomes for liver transplant recipients with severe hepatitis C virus (HCV) recurrence. In addition, the objective was to evaluate HCV recurrence as a risk factor for developing an OI.

METHODS

We conducted a retrospective observational study recording all liver transplant recipients from July 1, 2003, to December 31, 2012. Patients with liver disease due to HCV were selected. Active surveillance of infections was conducted periodically, and patients were classified according to presence of severe HCV recurrence.

RESULTS

Three hundred seventy patients underwent liver transplantation because of chronic HCV. One hundred forty-seven patients presented severe recurrence (SR) (49%) and 50 (17%) of them had post-liver transplant cholestatic hepatitis C. Patients with SR presented OI, especially cytomegalovirus (CMV) infections and invasive fungal infections, more frequently than patients without SR (33% vs 13%; P < .001). From the diagnosis of SR to the presentation of OI, the median number of days was 169 (6-2083). Acute allograft rejection (OR 1.8 95% confidence interval [CI] 1.1-3.3) donor age ≥60 years (OR 2.9 95% CI 1.3-6.8), and SR (OR 2.8, 95% CI 1.6-5.1) were independently associated with the development of OI in liver transplant recipients.

CONCLUSION

A high index of suspicion of opportunistic infections must be maintained when faced with severe HCV recurrence in liver transplant recipients. Moreover, active surveillance against CMV infection and other prophylactic strategies against opportunistic infections should be considered.

No effect of treatment with intravenous ganciclovir on Epstein-Barr virus viremia demonstrated after pediatric liver transplantation

EBV after pediatric LT is a risk factor for PTLD. We wanted to evaluate the effect of intravenous ganciclovir on EBV viremia and to identify risk factors for chronic EBV viremia. All pediatric patients who underwent LT in Norway from 2002 until 2015 were reviewed. Twenty-two of 38 patients with viremia were treated with intravenous ganciclovir for a median of 22 (21-38) days. Treated and untreated patients were not different with respect to EBV seroconversion prior to transplantation or age at transplantation, but treated patients had significantly earlier viremia after transplantation (P=.005). There was no difference in the proportion of patients with reduction in virus load in patients treated with ganciclovir compared to untreated patients at 8 weeks. After 1 year, five of 19 patients treated with ganciclovir and six of 14 untreated patients had reduced virus load compared to start of viremia (P=.27). In conclusion, treatment with intravenous ganciclovir did not change the proportion of patients with reduction in EBV load at 8 weeks and 1 year after viremia. Younger age at transplantation, short time from transplantation to viremia, and lack of EBV seroconversion prior to transplantation were significant predictors of chronic EBV viremia.

Infection in Organ Transplantation

The prevention, diagnosis, and management of infectious disease in transplantation are major contributors to improved outcomes in organ transplantation. The risk of serious infections in organ recipients is determined by interactions between the patient's epidemiological exposures and net state of immune suppression. In organ recipients, there is a significant incidence of drug toxicity and a propensity for drug interactions with immunosuppressive agents used to maintain graft function. Thus, every effort must be made to establish specific microbiologic diagnoses to optimize therapy. A timeline can be created to develop a differential diagnosis of infection in transplantation based on common patterns of infectious exposures, immunosuppressive management, and antimicrobial prophylaxis. Application of quantitative molecular microbial assays and advanced antimicrobial therapies have advanced care. Pathogen-specific immunity, genetic polymorphisms in immune responses, and dynamic interactions between the microbiome and the risk of infection are beginning to be explored. The role of infection in the stimulation of alloimmune responses awaits further definition. Major hurdles include the shifting worldwide epidemiology of infections, increasing antimicrobial resistance, suboptimal assays for the microbiologic screening of organ donors, and virus-associated malignancies. Transplant infectious disease remains a key to the clinical and scientific investigation of organ transplantation.

Adenovirus Interstitial Nephritis: An Unusual Cause for Early Graft Dysfunction

We describe a rare case of adenovirus interstitial nephritis in a 37-year-old man, 4 weeks following deceased donor renal transplantation. He presented with gross hematuria and acute graft dysfunction. A renal biopsy revealed necrotizing tubulointerstitial nephritis with intranuclear viral inclusions in the tubular epithelial cells. Immunohistochemistry and polymerase chain reaction confirmed adenovirus infection. Reduction in immunosuppression alone resulted in rapid improvement of graft function. Awareness of the clinical and characteristic biopsy findings may help establish the correct diagnosis, which is crucial as disseminated infection, if left untreated, is associated with a high mortality rate in renal allograft recipients.

Virion Glycoprotein-Mediated Immune Evasion by Human Cytomegalovirus: a Sticky Virus Makes a Slick Getaway

The prototypic herpesvirus human cytomegalovirus (CMV) exhibits the extraordinary ability to establish latency and maintain a chronic infection throughout the life of its human host. This is even more remarkable considering the robust adaptive immune response elicited by infection and reactivation from latency. In addition to the ability of CMV to exist in a quiescent latent state, its persistence is enabled by a large repertoire of viral proteins that subvert immune defense mechanisms, such as NK cell activation and major histocompatibility complex antigen presentation, within the cell. However, dissemination outside the cell presents a unique existential challenge to the CMV virion, which is studded with antigenic glycoprotein complexes targeted by a potent neutralizing antibody response. The CMV virion envelope proteins, which are critical mediators of cell attachment and entry, possess various characteristics that can mitigate the humoral immune response and prevent viral clearance. Here we review the CMV glycoprotein complexes crucial for cell attachment and entry and propose inherent properties of these proteins involved in evading the CMV humoral immune response. These include viral glycoprotein polymorphism, epitope competition, Fc receptor-mediated endocytosis, glycan shielding, and cell-to-cell spread. The consequences of CMV virion glycoprotein-mediated immune evasion have a major impact on persistence of the virus in the population, and a comprehensive understanding of these evasion strategies will assist in designing effective CMV biologics and vaccines to limit CMV-associated disease.

Adenovirus disease in six small bowel, kidney and heart transplant recipients; pathology and clinical outcome

Adenoviruses are emerging as important viral pathogens in hematopoietic stem cell and solid organ transplant recipients, impacting morbidity, graft survival, and even mortality. The risk seems to be highest in allogeneic hematopoietic stem cell transplant recipients as well as heart, lung, and small bowel transplant recipients. Most of the adenovirus diseases develop in the first 6 months after transplantation, particularly in pediatric patients. Among abdominal organ recipients, small bowel grafts are most frequently affected, presumably due to the presence of a virus reservoir in the mucosa-associated lymphoid tissue. Management of these infections may be difficult and includes the reduction of immunosuppression, whenever possible, combined with antiviral therapy, if necessary. Therefore, an awareness of the pathology associated with such infections is important in order to allow early detection and specific treatment. We reviewed six transplant recipients (small bowel, kidney, and heart) with adenovirus graft involvement from two institutions. We sought to compare the diagnostic morphology and the clinical and laboratory findings. The histopathologic features of an adenovirus infection of the renal graft and one native kidney in a heart transplant recipient included a vaguely granulomatous mixed inflammatory infiltrate associated with rare cells showing a cytopathic effect (smudgy nuclei). A lymphocytic infiltrate, simulating T cell rejection, with admixture of eosinophils was also seen. In the small bowel grafts, there was a focal mixed inflammatory infiltrate with associated necrosis in addition to cytopathic effects. In the heart, allograft adenovirus infection was silent with no evidence of inflammatory changes. Immunohistochemical stain for adenovirus was positive in all grafts and in one native kidney. All patients were subsequently cleared of adenovirus infection, as evidenced by follow-up biopsies, with no loss of the grafts. Adenovirus infection can involve allografts as well as native organs in solid organ transplant recipients. Infection is associated with variable necrosis and acute inflammation, in addition to a rejection-like infiltrate. Hematuria in non-renal solid organ transplant recipients may be associated with adenovirus nephritis and clinically silent graft involvement. Prompt diagnosis (aided by immunohistochemistry (IHC) and serology), with specific treatment, can prevent graft loss.

Prophylaxis versus pre-emptive treatment for prevention of cytomegalovirus infection in CMV-seropositive orthotopic liver-transplant recipients

This study compared the pre-emptive and the prophylactic strategies used to prevent cytomegalovirus (CMV) infection and disease in CMV-seropositive orthotopic liver-transplant recipients and searched for associated predictive factors. Seventy-three orthotopic liver-transplant recipients who had received a transplant before November 2005 were given ganciclovir IV pre-emptively (group I) and 56 recipients who had received a transplant after November 2005 were given prophylactic valganciclovir for 3 months (group II). Demographic and biochemical parameters did not statistically vary between the groups at baseline. Monitoring of CMV DNAemia was similar in both groups. Forty-two (57.5%) patients presented with CMV infection in group I and 18 (32.1%) in group II (P < 0.004). CMV DNAemia was first detected at a median of 33 days post-transplant in group I and at 98.5 days in group II (P < 0.003), but viral loads were not significantly different. The overall incidence of CMV disease was 9.6% in group I versus 7.1% in group II (ns). Thirty-five (47.9%) patients presented with biopsy-proven acute rejection in group I and 13 (23.2%) in group II (P = 0.004). Forty (55%) patients in group I and 25 (44.6%) in group II presented with de novo post-transplant diabetes (P = 0.057). At 1-year post-transplant, global survival curves were not significantly different. Independent factors associated with CMV reactivation were an absence of CMV prophylaxis, CMV serological status of the donor, cold ischemia time, and HLA A + B + DR compatibility. CMV prophylaxis is efficacious and can prevent safely the direct and indirect effects of CMV infection in CMV-seropositive orthotopic liver-transplant recipients.

Reactivation of multiple viruses in patients with sepsis

A current controversy is whether patients with sepsis progress to an immunosuppressed state. We hypothesized that reactivation of latent viruses occurred with prolonged sepsis thereby providing evidence of clinically-relevant immunosuppression and potentially providing a means to serially-monitor patients' immune status. Secondly, if viral loads are markedly elevated, they may contribute to morbidity and mortality. This study determined if reactivation of herpesviruses, polyomaviruses, and the anellovirus TTV occurred in sepsis and correlated with severity. Serial whole blood and plasma samples from 560 critically-ill septic, 161 critically-ill non-septic, and 164 healthy age-matched patients were analyzed by quantitative-polymerase-chain-reaction for cytomegalovirus (CMV), Epstein-Barr (EBV), herpes-simplex (HSV), human herpes virus-6 (HHV-6), and TTV. Polyomaviruses BK and JC were quantitated in urine. Detectable virus was analyzed with respect to secondary fungal and opportunistic bacterial infections, ICU duration, severity of illness, and survival. Patients with protracted sepsis had markedly increased frequency of detectable virus. Cumulative viral DNA detection rates in blood were: CMV (24.2%), EBV (53.2%), HSV (14.1%), HHV-6 (10.4%), and TTV (77.5%). 42.7% of septic patients had presence of two or more viruses. The 50% detection rate for herpesviruses was 5–8 days after sepsis onset. A small subgroup of septic patients had markedly elevated viral loads (>10⁴–10⁶ DNA copies/ml blood) for CMV, EBV, and HSV. Excluding TTV, DNAemia was uncommon in critically-ill non-septic patients and in age-matched healthy controls. Compared to septic patients without DNAemia, septic patients with viremia had increased fungal and opportunistic bacterial infections. Patients with detectable CMV in plasma had higher 90-day mortality compared to CMV-negative patients; p<0.05. Reactivation of latent viruses is common with prolonged sepsis, with frequencies similar to those occurring in transplant patients on immunosuppressive therapy and consistent with development of an immunosuppressive state. Whether reactivated latent viruses contribute to morbidity and mortality in sepsis remains unknown.

Analytical characterization of an assay designed to detect and identify diverse agents of disseminated viral infection

BACKGROUND

Diverse viruses often reactivate in or infect cancer patients, patients with immunocompromising infections or genetic conditions, and transplant recipients undergoing immunosuppressive therapy. These infections can disseminate, leading to death, transplant rejection, and other severe outcomes.

OBJECTIVES

To develop and characterize an assay capable of inclusive and accurate identification of diverse potentially disseminating viruses directly from plasma specimens.

STUDY DESIGN

We developed a PCR/electrospray ionization mass spectrometry (PCR/ESI-MS) assay designed to simultaneously detect and identify adenovirus, enterovirus, polyomaviruses JC and BK, parvovirus B19, HSV-1, HSV-2, VZV, EBV, CMV, and herpesviruses 6-8 in plasma specimens. The assay performance was characterized analytically, and the results from clinical plasma samples were compared to the results obtained from single-analyte real time PCR tests currently used in clinical practice.

RESULTS

The assay demonstrated sensitivity and specificity to diverse strains of the targeted viral families and robustness to interfering substances and potentially cross reacting organisms. The assay yielded 94% sensitivity when testing clinical plasma samples previously identified as positive using standard-of-care real-time PCR tests for a single target virus (available samples included positive samples for 11 viruses targeted by the assay).

CONCLUSIONS

The assay functioned as designed, providing simultaneous broad-spectrum detection and identification of diverse agents of disseminated viral infection. Among 156 clinical samples tested, 37 detections were made in addition to the detections matching the initial clinical positive results.

What do we know about adenovirus in renal transplantation?

Adenoviruses are common pathogens that have the potential to cause opportunistic infections with significant morbidity and mortality in immunocompromised hosts. The significance of adenoviral infection and disease is incompletely known in the setting of kidney transplantation. Reported adenovirus infections in renal transplant recipients have typically manifested as hemorrhagic cystitis and tubulointerstitial nephritis, less severe diseases than often seen in other solid organ transplant recipients (i.e. pneumonia, hepatitis and enteritis). The prevalent adenovirus subgroups associated with cystitis and nephritis are B1 and B2 with the serotypes 7, 11, 34, 35. However, disseminated or severe adenovirus infections, including fatal cases, have been described in renal transplant recipients. There is uncertainty regarding monitoring of and treatment of this virus. Although not supported by randomized clinical trials, cidofovir is used for the treatment of adenovirus disease not responding to reduction of immunosuppression.

Safety and efficacy of CMX001 as salvage therapy for severe adenovirus infections in immunocompromised patients

No therapeutic agent has yet been established as the definitive therapy for adenovirus infections. We describe the clinical experience of 13 immunocompromised patients who received CMX001 (hexadecyloxypropyl cidofovir), an orally bioavailable lipid conjugate of cidofovir, for adenovirus disease. We retrospectively analyzed 13 patients with adenovirus disease and viremia treated with CMX001; data were available for ≥ 4 weeks after initiation of CMX001 therapy. Virologic response (VR) was defined as a 99% drop from baseline or undetectable adenovirus DNA in serum. The median age of the group was 6 years (range, 0.92-66 years). One patient had severe combined immunodeficiency, 1 patient was a small bowel transplant recipient, and 11 were allogeneic stem cell transplant recipients. Adenovirus disease was diagnosed at a median of 75 days (range, 15-720 days) after transplantation. All patients received i.v. cidofovir for a median of 21 days (range, 5-90 days) before CMX001 therapy. The median absolute lymphocyte count at CMX001 initiation was 300 cells/μL (range, 7-1500 cells/μL). Eight patients (61.5%) had a ≥ 1 log10 drop in viral load after the first week of therapy. By week 8, 9 patients (69.2%) demonstrated a VR, with a median time to achieve VR of 7 days (range, 3-35 days). The change in absolute lymphocyte count was inversely correlated with the change in log10 viral load only at week 6 (r = -0.74; P = .03). Patients with VR had longer survival than those without VR (median 196 days versus 54.5 days; P = .04). No serious adverse events were attributed to CMX001 during therapy. CMX001 may be a promising therapeutic option for the treatment of severe adenovirus disease in immunocompromised patients.

Dominance of variant A in human herpesvirus 6 viraemia after renal transplantation

Background

Human herpesvirus 6 (HHV-6), mostly variant B reactivation in renal transplant patients has been published by other authors, but the pathogenetic role of HHV-6 variant A has not been clarified. Our aims were to examine the prevalence of HHV-6, to determine the variants, and to investigate the interaction between HHV-6 viraemia, human cytomegalovirus (HCMV) infection and clinical symptoms.

Methods

Variant-specific HHV-6 nested PCR and quantitative real-time PCR were used to examine blood samples from renal transplant patients and healthy blood donors for the presence and load of HHV-6 DNA and to determine the variants. Active HHV-6 infection was proved by RT-PCR, and active HCMV infection was diagnosed by pp65 antigenaemia test.

Results

HHV-6 viraemia was significantly more frequent in renal transplant patients compared to healthy blood donors (9/200 vs. 0/200; p = 0.004), while prevalence of HHV-6 latency was not significantly different (13/200 vs. 19/200; p > 0.05). Dominance of variant A was revealed in viraemias (8/9), and the frequency of HHV-6A was significantly higher in active infections compared with latency in renal transplant patients (8/9 vs. 2/13; p = 0.0015). Latency was established predominantly by HHV-6B both in renal transplant patients and in healthy blood donors (11/13 and 18/19). There was no statistical significant difference in occurrence of HCMV and HHV-6 viraemia in renal transplant patients (7/200 vs. 9/200). Statistical analysis did not reveal interaction between HHV-6 viraemia and clinical symptoms in our study.

Conclusions

Contrary to previous publications HHV-6A viraemia was found to be predominant in renal transplant patients. Frequency of variant A was significantly higher in cases of active infection then in latency.

Viral infections in lung transplant recipients

Viral infections, including beta-herpes viruses and community respiratory viruses, are frequent pathogens in lung transplant recipients. These pathogens have become increasingly recognized as having a significant role in long-term outcomes of lung transplantation, which has been limited by the frequent development of infections, and chronic allograft dysfunction. Community respiratory viruses, such as influenza and respiratory syncytial virus have been associated with both acute rejection and chronic allograft dysfunction, particularly if early treatment was not administered. beta-herpes viruses, particularly cytomegalovirus (CMV), have long been associated with increased mortality in lung transplant recipients, although the advent of effective antiviral strategies has led to improved morbidity and mortality. Because these pathogens have been associated with altered immune responses against the allograft, a better understanding of immunopathogenesis of viral infections may lead to a broader approach to limit the morbidity from these pathogens.

Transient detection of E1-containing adenovirus in saliva after the delivery of a first-generation adenoviral vector to human parotid gland

BACKGROUND

Radiation-induced salivary hypofunction is a common side-effect of treatment for head and neck cancers. Patients suffer significant morbidity and there is no suitable conventional therapy. We are conducting a Phase I clinical trial, using a first-generation serotype 5 adenoviral (Ad5) vector encoding human aquaporin-1 (AdhAQP1) to treat such patients. One week after the administration of AdhAQP1 to an enrolled, generally healthy patient, E1-containing adenovirus was detected in parotid saliva.

METHODS

The real-time quantitative polymerase chain reaction (PCR) was used to measure the Ad5 E1 gene and AdhAQP1 in saliva and serum. PCR and sequencing were used to characterize viral/vector DNA extracted from saliva. The presence of infectious adenovirus was assessed by the inoculation of A549 cells with aliquots of saliva. Serum Ad5 neutralizing antibodies were measured by the inhibition of 293-cell transduction with an Ad5 vector encoding luciferase. Multiple clinical evaluations were performed.

RESULTS

On day 7 after AdhAQP1 delivery, low levels of the Ad5 E1 gene were detected in parotid saliva (82 copies/microl). In addition, significant levels of AdhAQP1 were also detected (1.5 x 10(3) copies/microl). The patient was asymptomatic and subsequent analysis of parotid saliva samples prior to day 7 and after day 7 until day 42 was negative for both virus and vector. No virus or vector was detected in serum at any time. Detailed PCR analyses of DNA extracted from the day 7 parotid saliva sample suggested the absence of a recombination event, and no infectious virus was found.

CONCLUSIONS

The patient most likely had a latent Ad5 infection in the targeted parotid gland that was activated after gene transfer and was without clinical consequence.

Long-term virus-induced alterations of CYP3A-mediated drug metabolism: a look at the virology, immunology and molecular biology of a multi-faceted problem

Virus infections are on the rise. Although the first description of CYP expression during virus infection was recorded 50 years ago, mechanistic studies of this phenomenon only began to appear in the last decade due to breakthroughs in molecular biology, genomic and transgenic technology. This review describes the relationship(s) among CYP-mediated drug metabolism, virus infection and the immune response and evaluates in vitro and in vivo models for mechanistic studies. The first studies that assessed CYP expression during infection focused on inflammatory mediators and the innate immune response at early time points. Recent studies assessing virus infection and its effect on hepatic CYP expression noted more long-term effects. An obvious approach toward understanding how viruses affect hepatic CYP3A expression and function would be to assess key regulators of CYP during infection. Improvements in techniques to identify post-translational modifications of CYP and systems that focus on virus-receptor interactions which allow subtraction and addition of immunological and regulatory elements that drive CYP will demonstrate that long-term changes in drug metabolism start from the time the virus enters the circulation, are reinforced by virus binding to cellular targets and further solidified by changes in cellular processes long after the virus is cleared.

Contribution of human herpesvirus 6 (HHV-6) viral load in whole blood and serum to investigate integrated HHV-6 transmission after haematopoietic stem cell transplantation

BACKGROUND

Human herpesvirus 6 (HHV-6) is susceptible to latency and recurrence. A less-frequent form of HHV-6 persistence is the integration of viral DNA into host chromosomes.

OBJECTIVES

To investigate HHV-6 viral load after haematopoietic stem cell transplantation (HSCT) in whole blood (WB) and serum with regard to integrated HHV-6 transmission diagnosis.

STUDY DESIGN

HHV-6 DNA quantitation in serum and WB was performed using quantitative polymerase chain reaction for the follow-up of a 16-year-old girl after HSCT. In whole blood, results were expressed as HHV-6 genomic equivalent copies (gec) per milliliter of WB or per million cells.

RESULTS

HHV-6 viral load (undetectable before HSCT) increased up to 3.05 x 10(7)gec/10(6)cells. HHV-6 viral load in the donor sample (3.44 x 10(6)gec/10(6)cells) was in favor of viral transmission through HSCT. The correlation between viral load in WB and serum was significant (p=0.0005). Viral load results expressed as gec/10(6)cells in WB was more reliable than results expressed as gec/ml of whole blood.

CONCLUSION

These findings indicate that HHV-6 may be transmitted during HSCT as integrated virus contained in the graft. This reiterates that in the setting of HSCT, HHV-6 viral load must be correctly interpreted. Using HHV-6 viral load expressed as gec/10(6) cells may be more suitable for the follow-up of patients with integrated HHV-6.

Molecular and macromolecular alterations of recombinant adenoviral vectors do not resolve changes in hepatic drug metabolism during infection

In this report we test the hypothesis that long-term virus-induced alterations in CYP occur from changes initiated by the virus that may not be related to the immune response. Enzyme activity, protein expression and mRNA of CYP3A2, a correlate of human CYP3A4, and CYP2C11, responsive to inflammatory mediators, were assessed 0.25, 1, 4, and 14 days after administration of several different recombinant adenoviruses at a dose of 5.7 × 10¹² virus particles (vp)/kg to male Sprague Dawley rats. Wild type adenovirus, containing all viral genes, suppressed CYP3A2 and 2C11 activity by 37% and 39%, respectively within six hours. Levels fell to 67% (CYP3A2) and 79% (CYP2C11) of control by 14 days (p ≤ 0.01). Helper-dependent adenovirus, with all viral genes removed, suppressed CYP3A2 (43%) and CYP2C11 (55%) within six hours. CYP3A2 remained significantly suppressed (47%, 14 days, p ≤ 0.01) while CYP2C11 returned to baseline at this time. CYP3A2 and 2C11 were reduced by 45 and 42% respectively 6 hours after treatment with PEGylated adenovirus, which has a low immunological profile (p ≤ 0.05). CYP3A2 remained suppressed (34%, p ≤ 0.05) for 14 days while CYP2C11 recovered. Inactivated virus suppressed CYP3A2 activity by 25–50% for 14 days (p ≤ 0.05). CYP2C11 was affected similar manner but recovered by day 14. Microarray and in vitro studies suggest that changes in cellular signaling pathways initiated early in virus infection contribute to changes in CYP.

Cytomegalovirus prophylaxis with valganciclovir in cytomegalovirus-seropositive kidney-transplant patients

The aims of this prospective, open-label, single-center pilot study were to assess the efficacy and safety of human cytomegalovirus (HCMV) prophylaxis using valganciclovir in HCMV- seropositive kidney-transplant patients to prevent HCMV infection and disease. Fifty-one HCMV seropositive kidney-transplant patients recipients who received transplants between 1 December 2005 and 30 November 2006 were included in the study. Valganciclovir was given from transplantation up to 114 (37-329) days, and was adapted to renal function, i.e., 900 mg/d if calculated creatinine clearance was >60 ml/min, or 450 mg/day if it was <60 ml/min. HCMV DNAemia was assessed every 2 weeks during prophylaxis, and on the same basis for 3 months post-prophylaxis. Immunosuppression was based on calcineurin inhibitors (ciclosporine A=22; tacrolimus=11), with mycophenolate mofetil (n=51), and low-dose steroids. Eighteen patients received no calcineurin-inhibitors, but Belatacept instead. During valganciclovir prophylaxis, asymptomatic HCMV DNAemia was observed in one patient, and no case of HCMV disease occurred. Within 252 days (45-425) post-valganciclovir prophylaxis, HCMV DNAemia was detected in 23.5% (n=12) of patients, of whom two had two or more consecutive HCMV DNAemias. Valganciclovir prophylaxis in HCMV-seropositive kidney-transplant patients is effective for preventing cytomegalovirus disease.

Predictive factors for cytomegalovirus reactivation in cytomegalovirus-seropositive kidney-transplant patients

The aims of the present study were to assess the incidence of cytomegalovirus (CMV) reactivation, and to determine the predictive factors for CMV reactivation in CMV seropositive kidney-transplant patients. One hundred ninety CMV seropositive kidney-transplant patients were included in this study; of these, 39 patients had received CMV prophylaxis. CMV DNAemia was assessed by real-timepolymerase chain reaction assay every 2 weeks until day 120, then every 3-4 weeks until day 180, and then every month until day 365. One hundred seven patients (56.3%) had at least one positive CMV DNAemia within the first year. The time between renal transplantation and the first positive CMV DNAemia was 59 +/- 5 days. The number of positive CMV DNAemia/patient was 3.28 +/- 0.22. CMV viral load at first positive CMV DNAemia was 704 (10-742,000) copies/ml. The donor CMV seropositivity, the absence of CMV prophylaxis, and the occurrence of acute rejection before CMV reactivation were independent factors associated with CMV reactivation within the first year after kidney transplantation. Hence, CMV reactivation is frequent after kidney transplantation. CMV prophylaxis in CMV seropositive kidney-transplant patients should be offered to avoid CMV-related side-effects.

Human herpesvirus 7 primary infection in kidney transplant recipients

The aims of the study were to evaluate the incidence and the clinical implications of human herpesvirus (HHV)-7 primary infection in patients undergoing kidney transplantation and the probable interactions between the three beta-herpesviruses (cytomegalovirus [CMV], HHV-6, and HHV-7). Sixty kidney transplant recipients had sequential plasma and whole blood samples collected prior to transplantation and at 7, 14, 21, 28, 45, 60, 75, 90, and 180 days posttransplantation. We used indirect immunofluorescence assays to detect HHV-7 immunoglobulin (Ig) G antibodies in plasma and quantitative real-time polymerase chain reaction to assess CMV, HHV-6 and HHV-7 viral loads. Sixteen out of 60 patients (27%) did not show HHV-7 IgG antibodies prior to transplantation and they were selected for this study. Whereas 3 (18.75%) out of the 16 HHV-7 seronegative patients seroconverted after transplantation, only one patient (6%) had a high HHV-7 viral load from the seventh day posttransplantation in consecutive blood samples during follow-up without clinical manifestations. In our study, the incidence of posttransplant HHV-7 primary infection was low and asymptomatic.

HHV-6 DNA in peripheral blood mononuclear cells after liver transplantation

BACKGROUND

Human herpesvirus-6 (HHV-6) infections have been reported after liver transplantation. In this study, the detection of HHV-6 DNA in peripheral blood mononuclear cells (PBMC) was compared with HHV-6 antigenemia in liver transplant patients.

OBJECTIVES

Forty-three adult liver recipients were frequently monitored by HHV-6 antigenemia test, which detects the viral antigens in PBMC, but is rather qualitative than quantitative.

STUDY DESIGN

From the same PBMC specimens HHV-6 DNA was demonstrated by in situ hybridization using a biotinylated probe and quantified as positive cells/10, 000 PBMC. Altogether 330 blood specimens were analyzed.

RESULTS

During the first 6 months (mean 12 days) after transplantation, 35/43 patients developed HHV-6 antigenemia. Concurrently, HHV-6 DNA-positive cells with mean peak number of 661(+/-574)/10, 000 were detected in 33/35 patients. Seven patients received ganciclovir treatment because of concurrent CMV infection with mean peak number of HHV-6 DNA-positive cells 381(+/-336) before and 34(+/-59)/10, 000 after the treatment (p = 0.03). All CMV infections responded to ganciclovir, but HHV-6 DNAemia disappeared slowly, within 79 days (mean 36 days). Without antivirals, HHV-6 DNAemia/antigenemia lasted usually longer.

CONCLUSIONS

Detection of HHV-6 DNA in PBMC correlated well with HHV-6 antigenemia, and may be used in the monitoring of transplant patients.

Primer: histopathology of polyomavirus-associated nephropathy in renal allografts

The BK polyomavirus exhibits tropism for the renal tubular epithelium, where it establishes latent infection. Vigorous immunosuppression of renal allograft recipients can lead to reactivation of the infection and the development of polyomavirus-associated nephropathy (PVAN). Clinically, gradually decreasing renal function, viremia and viruria are observed several months after transplantation; allograft failure occurs in 1-10% of patients. Definitive diagnosis requires an allograft biopsy. Histologically, viral replication results in tubular epithelial cell enlargement, karyomegaly and nuclear inclusion bodies. The cytopathic changes are often associated with lysis of tubular epithelial cells, denudation of the basement membrane and an interstitial inflammatory response. The involvement is multifocal; distal nephron segments are more severely affected than proximal segments. Changes observed during light microscopy are suggestive but not pathognomonic for PVAN, and the diagnosis must be confirmed by adjunct studies. Adjunct studies consist of immunohistochemistry on paraffin sections using an antibody to the SV40 large T antigen, or electron microscopy of infected tubular epithelial cells (virions 40 nm in diameter). PVAN manifests in three histologic patterns: pattern A, viral cytopathic changes with no or only minimal inflammation; pattern B, cytopathic and cytolytic lesions with interstitial inflammation; or pattern C, predominantly interstitial fibrosis and tubular atrophy, with variable cytopathic and inflammatory changes. These patterns correlate with clinical outcomes.