Monitoring of Epstein-Barr virus load after hematopoietic stem cell transplantation for early intervention in post-transplant lymphoproliferative disease

Combination of proviral and antiviral roles of B cell-intrinsic STAT1 expression defines parameters of chronic gammaherpesvirus infection

Gammaherpesviruses are species-specific, ubiquitous pathogens that establish lifelong infection in their hosts and are associated with cancers, including B cell lymphomas. Type I and II interferons (IFNs) are critical for the control of acute and chronic gammaherpesvirus infection. However, the cell type-specific role of IFN signaling during natural infection is poorly defined and is masked by the altered viral pathogenesis observed in hosts with global IFN deficiencies. STAT1 is a constitutively expressed transcription factor that is critical for the effector function of type I and II IFNs. In this study, we defined the impact of B cell-specific STAT1 expression on gammaherpesvirus infection using murine gammaherpesvirus 68 (MHV68). While the acute stage of MHV68 infection was not affected, we found opposite, anatomic site-dependent effects of B cell-intrinsic STAT1 expression during chronic infection. Consistent with the antiviral role of STAT1, B cell-specific STAT1 expression attenuated the latent viral reservoir in peritoneal B cells of chronically infected mice. In contrast, STAT1 expression in splenic B cells supported the establishment of the latent MHV68 reservoir in germinal center B cells, revealing an unexpected proviral role of B cell-intrinsic STAT1 expression during chronic gammaherpesvirus infection. These STAT1-dependent MHV68 chronic infection phenotypes were fully recapitulated in the peritoneal cavity but not the spleen of mice with B cell-specific deficiency of type I IFN receptor. In summary, our study uncovers the intriguing combination of proviral and antiviral roles of B cell-intrinsic STAT1 expression during chronic gammaherpesvirus infection.IMPORTANCEInterferons (IFNs) execute broadly antiviral roles during acute and chronic viral infections. The constitutively expressed transcription factor STAT1 is a critical downstream effector of IFN signaling. Our studies demonstrate that B cell-intrinsic STAT1 expression has opposing and anatomic site-dependent roles during chronic gammaherpesvirus infection. Specifically, B cell-intrinsic STAT1 expression restricted gammaherpesvirus latent reservoir in the peritoneal cavity, consistent with the classical antiviral role of STAT1. In contrast, decreased STAT1 expression in splenic B cells led to the attenuated establishment of gammaherpesvirus latency and decreased latent infection of germinal center B cells, highlighting a novel proviral role of B cell-intrinsic STAT1 expression during chronic infection with a B cell-tropic gammaherpesvirus. Interestingly, B cell-specific type I IFN receptor deficiency primarily recapitulated the antiviral role of B cell-intrinsic STAT1 expression, suggesting the compensatory function of B cell-intrinsic type II IFN signaling or an IFN-independent proviral role of B cell-intrinsic STAT1 expression during chronic gammaherpesvirus infection.

Nontypeable Haemophilus influenzae challenge during gammaherpesvirus infection enhances viral reactivation and latency

Gammaherpesviruses are ubiquitous, lifelong pathogens associated with multiple cancers that infect over 95% of the adult population. Increases in viral reactivation, due to stress and other unknown factors impacting the immune response, frequently precedes lymphomagenesis. One potential stressor that could promote viral reactivation and increase viral latency would be the myriad of infections from bacterial and viral pathogens that we experience throughout our lives. Using murine gammaherpesvirus 68 (MHV68), a mouse model of gammaherpesvirus infection, we examined the impact of bacterial challenge on gammaherpesvirus infection. We challenged MHV68 infected mice during the establishment of latency with nontypeable Haemophilus influenzae (NTHi) to determine the impact of bacterial infection on viral reactivation and latency. Mice infected with MHV68 and then challenged with NTHi, saw increases in viral reactivation and viral latency. These data support the hypothesis that bacterial challenge can promote gammaherpesvirus reactivation and latency establishment, with possible consequences for viral lymphomagenesis.

Diagnostic Value of Whole-Blood and Plasma Samples in Epstein-Barr Virus Infections

Epstein-Barr virus (EBV) is an oncogenic virus classified by the World Health Organization as a class 1 carcinogen. Post-transplant lymphoproliferative disorders are believed to be strongly related to an EBV infection. Monitoring of EBV DNAemia is recommended to assess the risk of reactivation of latent infection and to assess the effectiveness of therapy. Currently, various types of clinical specimens are used for this purpose. The aim of the study was to assess a reliable method of EBV viral load investigation depending on the clinical material used: whole blood or plasma samples. We found that of 134 EBV-DNA-positive whole-blood samples derived from 51 patients (mostly hemato-oncology or post-transplantation), only 43 (32.1%) were plasma-positive. Of these, 37 (86.0%) had lower plasma DNAemia compared to the corresponding whole-blood samples. We conclude that whole-blood samples have a higher sensitivity than plasma samples in EBV DNA detection. The clinical utility of the tests is unclear, but our results suggest that either whole blood or plasma should be used consistently for EBV viral load monitoring.

T Cell-Intrinsic Interleukin 17 Receptor A Signaling Supports the Establishment of Chronic Murine Gammaherpesvirus 68 Infection

Gammaherpesviruses, such as human Epstein-Barr virus (EBV) and murine gammaherpesvirus 68 (MHV68), are species-specific, ubiquitous pathogens that are associated with multiple cancers, including B cell lymphomas. These viruses have a natural tropism for B cells and usurp B cell differentiation to drive a unique and robust polyclonal germinal center response to establish a long-term latent reservoir in memory B cells. The robust polyclonal germinal center response driven by gammaherpesvirus infection increases the risk for B cell transformation. Unsurprisingly, many gammaherpesvirus cancers are derived from germinal center or post-germinal center B cells. The viral and host factors that influence the gammaherpesvirus-driven germinal center response are not clearly defined. We previously showed that host interleukin 17 receptor A (IL-17RA) signaling promotes the establishment of chronic MHV68 infection and the MHV68-driven germinal center response. In this study, we found that T cell-intrinsic IL-17RA signaling recapitulates some proviral aspects of global IL-17RA signaling during MHV68 infection. Specifically, we found that T cell-intrinsic IL-17RA signaling supports the MHV68-driven germinal center response, the establishment of latency in the spleen, and viral reactivation in the spleen and peritoneal cavity. Our study unveils an unexpected finding where the T cell-specific IL-17RA signaling supports the establishment of a latent reservoir of a B cell-tropic gammaherpesvirus. IMPORTANCE Gammaherpesviruses, such as human EBV, establish lifelong infection in >95% of adults and are associated with B cell lymphomas. Gammaherpesviruses usurp the germinal center response to establish latent infection, and the germinal center B cells are thought to be the target of viral transformation. We previously found that global expression of IL-17RA promotes the establishment of chronic MHV68 infection and the MHV68-driven germinal center response. In this study, we showed that T cell-intrinsic IL-17RA signaling is necessary to promote the MHV68-driven germinal center response by supporting CD4⁺ T follicular helper cell expansion. We also found that T cell-intrinsic IL-17RA signaling contributes to but is not solely responsible for the systemic proviral role of IL-17RA signaling, highlighting the multifaceted function of IL-17RA signaling during MHV68 infection.

Prognostic Factors on Graft Function in Pediatric Kidney Recipients

BACKGROUND

Graft survival in pediatric kidney transplant recipients has increased in the last decades. Determining prognostic factors for graft function over time allows the identification of patients at risk for graft loss and could lead to improvement of current guidelines.

METHODS

Data were collected among pediatric kidney transplant recipients in a single center during the first 5 years after transplantation. Mixed model analysis was used to indicate possible prognostic factors for the loss of graft function.

RESULTS

A total of 100 pediatric kidney transplant recipients were analyzed. Negative prognostics of graft function are higher donor age and higher recipient age, presence of obstructive uropathology, re-transplant, and occurrence of BK viremia. The negative influence on graft function of both donor age and presence of obstructive uropathology increased over time. In this study, the factors that did not influence graft function over time were the number of HLA mismatches, pre-transplant dialysis, intra-abdominal graft placement, ischemia time, occurrence of acute rejection, presence of lower urinary tract dysfunction, occurrence of urinary tract infections, and infections with cytomegalovirus and Epstein-Barr virus.

CONCLUSIONS

This study showed that a higher donor age and higher recipient age, presence of obstructive uropathology, a re-transplant, and the occurrence of BK viremia were negative prognostic factors of graft function over time, in the first 5 years after transplant. Graft function was comparable between steroid-sparing regimens (preferable in low-risk patients) and regimens including steroids (for special reasons).

Interferon Regulatory Factor 7 Attenuates Chronic Gammaherpesvirus Infection

Gammaherpesviruses are ubiquitous pathogens that establish lifelong infections and are associated with a variety of malignancies, including lymphomas. Interferon regulatory factor 7 (IRF-7) is an innate immune transcription factor that restricts acute replication of diverse viruses, including murine gammaherpesvirus 68 (MHV68). Importantly, very little is known about the role of IRF-7 during chronic virus infections. In this study, we demonstrate that IRF-7 attenuates chronic infection by restricting establishment of gammaherpesvirus latency in the peritoneal cavity and, to a lesser extent, viral reactivation in the spleen. Despite the classical role of IRF-7 as a stimulator of type I interferon (IFN) transcription, there were no global effects on the expression of IFN-induced genes (ISGs) in the absence of IRF-7, with only a few ISGs showing attenuated expression in IRF-7-deficient peritoneal cells. Further, IRF-7 expression was dispensable for the induction of a virus-specific CD8 T cell response. In contrast, IRF-7 expression restricted latent gammaherpesvirus infection in the peritoneal cavity under conditions where the viral latent reservoir is predominantly hosted by peritoneal B cells. This report is the first demonstration of the antiviral role of IRF-7 during the chronic stage of gammaherpesvirus infection.IMPORTANCE The innate immune system of the host is critical for the restriction of acute viral infections. In contrast, the role of the innate immune network during chronic herpesvirus infection remains poorly defined. Interferon regulatory factor 7 (IRF-7) is a transcription factor with many target genes, including type I interferons (IFNs). In this study, we show that the antiviral role of IRF-7 continues into the chronic phase of gammaherpesvirus infection, wherein IRF-7 restricts the establishment of viral latency and viral reactivation. This study is, to our knowledge, the first to define the role of IRF-7 in chronic virus infection.

Reducing infectious complications after allogeneic stem cell transplant

INTRODUCTION

Infections remain a significant problem, in patients undergoing an allogeneic hematopoietic stem-cell transplant (HSCT) and efforts have been made over the years, to reduce the incidence, morbidity and mortality of infectious complications.

AREAS COVERED

This manuscript is focused on the epidemiology, risk factors and prevention of infections after allogeneic HSCT. A systematic literature review was performed using the PubMed database, between November 2019 and January 2020, with the following MeSH terms: stem-cell transplantation, infection, fungal, bacterial, viral, prophylaxis, vaccines, prevention. The authors reviewed all the publications, and following a common revision, a summary report was made and results were divided in three sections: bacterial, fungal and viral infections.

EXPERT OPINION

Different infections occur in the early, intermediate and late post-transplant period, due to distinct risk factors. Improved diagnostic techniques, pre-emtive therapy and better prophylaxis of immunologic complications, have reduced the morbidity and mortality of infections. The role of the gut microbiota is under careful scrutiny and may further help us to identify high-risk patients.

Innate immunity and alpha/gammaherpesviruses: first impressions last a lifetime

Innate immune system is considered the first line of defense during viral invasion, with the wealth of the literature demonstrating innate immune control of diverse viruses during acute infection. What is far less clear is the role of innate immune system during chronic virus infections. This short review focuses on alphaherpesviruses and gammaherpesviruses, two highly prevalent herpesvirus subfamilies that, following a brief, once in a lifetime period of acute lytic infection, establish life-long latent infection that is characterized by sporadic reactivation in an immunocompetent host. In spite of many similarities, these two viral families are characterized by distinct cellular tropism and pathogenesis. Here we focus on the published in vivo studies to review known interactions of these two viral subfamilies with the innate immunity of the intact host, both during acute and, particularly, chronic virus infection.

Post-transplantation lymphoproliferative disorders: Current concepts and future therapeutic approaches

Transplant recipients are vulnerable to a higher risk of malignancy after solid organ transplantation and allogeneic hematopoietic stem-cell transplant. Post-transplant lymphoproliferative disorders (PTLD) include a wide spectrum of diseases ranging from benign proliferation of lymphoid tissues to frank malignancy with aggressive behavior. Two main risk factors of PTLD are: Firstly, the cumulative immunosuppressive burden, and secondly, the oncogenic impact of the Epstein-Barr virus. The latter is a key pathognomonic driver of PTLD evolution. Over the last two decades, a considerable progress has been made in diagnosis and therapy of PTLD. The treatment of PTLD includes reduction of immunosuppression, rituximab therapy, either isolated or in combination with other chemotherapeutic agents, adoptive therapy, surgical intervention, antiviral therapy and radiotherapy. In this review we shall discuss the prevalence, clinical clues, prophylactic measures as well as the current and future therapeutic strategies of this devastating disorder.

Automated quantification of Epstein-Barr virus in whole blood for post-transplant lymphoproliferative disorders monitoring

Background

Standardized and sensitive assays for Epstein Barr Virus (EBV) are needed to define universal cutoff for treatment initiation in allogeneic hematopoietic stem cells transplant recipients. In a context of accreditation and the availability of EBV international standard, we evaluated the Abbott RealTime EBV (RT) assay for EBV quantification in whole blood.

Methods

The RT assay was compared on 282 prospective clinical samples with the Artus EBV PCR Kit V1 assay (V1) and we analyzed the kinetics of EBV load in 11 patients receiving rituximab treatment.

Results

The estimated limit of detection was 88 IU/mL. The assay was linear (r² = 0.9974) in the range of all samples tested (100 to 1,000,000 IU/mL). Intra-assay coefficients of variation (CV) ranged between 0.35 and 1.35%, and inter-assay CV between 3.40 and 4.5%. On samples above the limit of quantification, the two assays were strongly correlated. EBV RT values were on average 0.30 log₁₀ IU/mL lower than those measured with the V1 assay. In patients treated with rituximab, the RT assay remained positive in 5 patients at the time it dropped below undetectable levels with the V1 assay.

Conclusions

In conclusion, the RT assay is a reliable assay for EBV load in whole blood. Its sensitivity will enable to estimate the kinetics of EBV load and the impact of treatments to control EBV reactivations.

High pretreatment plasma Epstein-Barr virus (EBV) DNA level is a poor prognostic marker in HIV-associated, EBV-negative diffuse large B-cell lymphoma in Malawi

Plasma Epstein-Barr virus (EBV) DNA measurement has established prognostic utility in EBV-driven lymphomas, where it serves as a circulating tumor DNA marker. The value of plasma EBV measurement may be amplified in sub-Saharan Africa (SSA), where advanced imaging and molecular technologies for risk stratification are not typically available. However, its utility in diffuse large B-cell lymphoma (DLBCL) is less certain, given that only a subset of DLBCLs are EBV-positive. To explore this possibility, we measured plasma EBV DNA at diagnosis in a cohort of patients with DLBCL in Malawi. High plasma EBV DNA at diagnosis (≥3.0 log10 copies/mL) was associated with decreased overall survival (OS) (P = .048). When stratified by HIV status, the prognostic utility of baseline plasma EBV DNA level was restricted to HIV-positive patients. Unexpectedly, most HIV-positive patients with high plasma EBV DNA at diagnosis had EBV-negative lymphomas, as confirmed by multiple methods. Even in these HIV-positive patients with EBV-negative DLBCL, high plasma EBV DNA remained associated with shorter OS (P = .014). These results suggest that EBV reactivation in nontumor cells is a poor prognostic finding even in HIV-positive patients with convincingly EBV-negative DLBCL, extending the potential utility of EBV measurement as a valuable and implementable prognostic marker in SSA.

LXR Alpha Restricts Gammaherpesvirus Reactivation from Latently Infected Peritoneal Cells

Gammaherpesviruses are ubiquitous viruses that establish lifelong infections. Importantly, these viruses are associated with numerous cancers and lymphoproliferative diseases. While risk factors for developing gammaherpesvirus-driven cancers are poorly understood, it is clear that elevated viral reactivation from latency often precedes oncogenesis. Here, we demonstrate that the liver X receptor alpha isoform (LXRα) restricts gammaherpesvirus reactivation in an anatomic-site-specific manner. We have previously demonstrated that deficiency of both LXR isoforms (α and β) leads to an increase in fatty acid and cholesterol synthesis in primary macrophage cultures, with a corresponding increase in gammaherpesvirus replication. Interestingly, expression of fatty acid synthesis genes was not derepressed in LXRα-deficient hosts, indicating that the antiviral effects of LXRα are independent of lipogenesis. Additionally, the critical host defenses against gammaherpesvirus reactivation, virus-specific CD8⁺ T cells and interferon (IFN) signaling, remained intact in the absence of LXRα. Remarkably, using a murine gammaherpesvirus 68 (MHV68) reporter virus, we discovered that LXRα expression dictates the cellular tropism of MHV68 in the peritoneal cavity. Specifically, LXRα^-/- mice exhibit reduced latency within the peritoneal B cell compartment and elevated latency within F4/80⁺ cells. Thus, LXRα restricts gammaherpesvirus reactivation through a novel mechanism that is independent of the known CD8⁺ T cell-based antiviral responses or changes in lipid synthesis and likely involves changes in the tropism of MHV68 in the peritoneal cavity.IMPORTANCE Liver X receptors (LXRs) are nuclear receptors that mediate cholesterol and fatty acid homeostasis. Importantly, as ligand-activated transcription factors, LXRs represent potential targets for the treatment of hypercholesterolemia and atherosclerosis. Here, we demonstrate that LXRα, one of the two LXR isoforms, restricts reactivation of latent gammaherpesvirus from peritoneal cells. As gammaherpesviruses are ubiquitous oncogenic agents, LXRs may represent a targetable host factor for the treatment of poorly controlled gammaherpesvirus infection and associated lymphomagenesis.

Prevention of Infections in Patients with Hematological Malignancies

Infection is a major complication of patients with hematological malignancies. Prophylaxis is a key element in the management of these patients, and is composed by two main components: infection control measures and antimicrobial chemoprophylaxis. Infection control measures are safe, but not always effective. Antimicrobial prophylaxis is usually effective but may increase resistance rates, toxicity, and cost. Therefore, a careful evaluation of the actual risk for infection, the pathogens that predominate in a particular setting, and the periods at risk are important in order to define the most appropriate strategy. In this chapter we review the most important parameters to assess the risk on an individual basis, and the evidences and recommendations supporting infection control measures and antimicrobial prophylaxis against bacteria, fungi, viruses, and parasites.

Molecular Microbiology

Background

Nucleic acid (NA) amplification techniques are now commonly used to diagnose and manage patients with infectious diseases. The growth in the number of Food and Drug Administration–approved test kits and analyte-specific reagents has facilitated the use of this technology in clinical laboratories. Technological advances in NA amplification techniques, automation, NA sequencing, and multiplex analysis have reinvigorated the field and created new opportunities for growth. Simple, sample-in, answer-out molecular test systems are now widely available that can be deployed in a variety of laboratory and clinical settings. Molecular microbiology remains the leading area in molecular pathology in terms of both the numbers of tests performed and clinical relevance. NA-based tests have reduced the dependency of the clinical microbiology laboratory on more traditional antigen detection and culture methods and created new opportunities for the laboratory to impact patient care.

Content

This chapter reviews NA testing as it applies to specific pathogens or infectious disease syndromes, with a focus on those diseases for which NA testing is now considered the standard of care and highlights the unique challenges and opportunities that these tests present for clinical laboratories.

ATM supports gammaherpesvirus replication by attenuating type I interferon pathway

Ataxia-Telangiectasia mutated (ATM) kinase participates in multiple networks, including DNA damage response, oxidative stress, and mitophagy. ATM also supports replication of diverse DNA and RNA viruses. Gammaherpesviruses are prevalent cancer-associated viruses that benefit from ATM expression during replication. This proviral role of ATM had been ascribed to its signaling within the DNA damage response network; other functions of ATM have not been considered. In this study increased type I interferon (IFN) responses were observed in ATM deficient gammaherpesvirus-infected macrophages. Using a mouse model that combines ATM and type I IFN receptor deficiencies we show that increased type I IFN response in the absence of ATM fully accounts for the proviral role of ATM during gammaherpesvirus replication. Further, increased type I IFN response rendered ATM deficient macrophages more susceptible to antiviral effects of type II IFN. This study identifies attenuation of type I IFN responses as the primary mechanism underlying proviral function of ATM during gammaherpesvirus infection.

Epstein-Barr virus and cytomegalovirus infections and their clinical relevance in Egyptian leukemic pediatric patients

Background

Epstein-Barr virus (EBV) and human cytomegalovirus (CMV) infections are environmental risk factors affecting the outcome of cancer due to an impairment in the cell-mediated immunity. Therefore, this study aimed to detect the frequency of EBV and CMV DNA and their association with clinical characteristics and outcome of pediatric leukemic patients.

Methods

Samples of 50 immunocompromised pediatric leukemic patients and 30 apparently healthy children were subjected to the amplification of EBV DNA by one version of PCR targeting the Bam H1 W region of the genomic region of EBV, and the amplification of CMV DNA by targeting the CMV UL97 genomic region by a second round PCR. All investigations were performed on WBCs and sera. Results were correlated with the clinical and laboratory characteristics of the disease, and with overall survival.

Results

EBV and CMV DNA were detected in 20 and 54% of leukemic patients, respectively. Nine out of ten patients with EBV DNA (90%) were positive for CMV DNA in their sera. The presence of EBV DNA or CMV DNA was associated with neutropenia and a low total leukocyte count (TLC) (p = 0.02, 0.03, respectively). The presence of severe CMV disease, longer duration of febrile neutropenia, neutropenia, lymphopenia, thrombocytopenia and the presence of EBV DNA in patients’ sera were significantly associated with worse overall survival.

Conclusion

The detection of CMV disease and EBV DNA is relatively common in leukemic children and is significantly associated with a decline in the overall survival.

Dynamics of Epstein-Barr viral load after hematopoietic stem cell transplantation and effect of preemptive rituximab therapy

BACKGROUND

Epstein-Barr virus (EBV) displays oncogenic properties, particularly in the immunocompromised host. Notably, hematopoietic stem cell transplantation (HSCT) recipients with a detectable blood EBV viral load (BEBVL) are considered at higher risk of post-transplant lymphoproliferative diseases (PTLD). Therefore, BEBVL is monitored after HSCT, and preemptive rituximab may be used in patients with high values. However, little is known about post-HSCT BEBVL dynamics, and the threshold that should lead to anti-CD20 therapy is poorly defined.

METHODS

We retrospectively analyzed the post-HSCT BEBVL of 332 adult HSCT recipients in our center from 2005 to 2013, including the effect of rituximab.

RESULTS

Detection of BEBVL >100, 1000, 5000, 10 000, and 50 000 copies/mL occurred in, respectively, 77.7%, 69.6%, 37.0%, 27.1%, and 7.5% of the patients after a respective median time of 9, 14, 15, 16, and 14 weeks. No BEBVL threshold was associated with an overall survival difference. Seventy-eight patients received rituximab, with a BEBVL decrease in most. Among patients with detectable BEBVL, long-term survival did not differ in rituximab treated and non-treated, except for patients with BEBVL ≥50 000. Only one case of PTLD was observed.

CONCLUSIONS

BEBVL is frequently detectable after HSCT, but suggests no strong association with survival. Preemptive rituximab therapy threshold remains to be defined.

Infectious diseases in allogeneic haematopoietic stem cell transplantation: prevention and prophylaxis strategy guidelines 2016

Infectious complications after allogeneic haematopoietic stem cell transplantation (allo-HCT) remain a clinical challenge. This is a guideline provided by the AGIHO (Infectious Diseases Working Group) of the DGHO (German Society for Hematology and Medical Oncology). A core group of experts prepared a preliminary guideline, which was discussed, reviewed, and approved by the entire working group. The guideline provides clinical recommendations for the preventive management including prophylactic treatment of viral, bacterial, parasitic, and fungal diseases. The guideline focuses on antimicrobial agents but includes recommendations on the use of vaccinations. This is the updated version of the AGHIO guideline in the field of allogeneic haematopoietic stem cell transplantation utilizing methods according to evidence-based medicine criteria.

An overview of infectious complications after allogeneic hematopoietic stem cell transplantation

Infections are the most common and significant cause of mortality and morbidity after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The presence of neutropenia and mucosal damage are the leading risk factors in the early pre-engraftment phase. In the early post-engraftment phase, graft versus host disease (GvHD) induced infection risk is increased in addition to catheter related infections. In the late phase, in which reconstitution of cellular and humoral immunity continues, as well as the pathogens seen during the early post-engraftment phase, varicella-zoster virus and encapsulated bacterial infections due to impaired opsonization are observed. An appropriate vaccination schedule following the cessation of immunosuppressive treatment after transplantation, intravenous immunoglobulin administration, and antimicrobial prophylaxis with penicillin or macrolide antibiotics during immunosuppressive treatment for GvHD might decrease the risk of bacterial infections. Older age, severe mucositis due to toxicity of chemotherapy, gastrointestinal tract colonization, prolonged neutropenia, unrelated donor and cord blood originated transplantations, acute and chronic GvHD are among the most indicative clinical risk factors for invasive fungal infections. Mold-active anti-fungal prophylaxis is suggested regardless of the period of transplantation among high risk patients. The novel serological methods, including Aspergillus galactomannan antigen and beta-D-glucan detection and computed tomography are useful in surveillance. Infections due to adenovirus, influenza and respiratory syncytial virus are encountered in all phases after allo-HSCT, including pre-engraftment, early post-engraftment and late phases. Infections due to herpes simplex virus-1 and -2 are mostly seen during the pre-engraftment phase, whereas, infections due to cytomegalovirus and human herpes virus-6 are seen in the early post-engraftment phase and Epstein-Barr virus and varicella-zoster virus infections often after +100th day. In order to prevent mortality and morbidity of infections after allo-HSCT, the recipients should be carefully followed-up with appropriate prophylactic measures in the post-transplant period.

Epstein-Barr virus-associated leukemic lymphoma after allogeneic stem cell transplantation

Leukemic Epstein-Barr virus (EBV)-associated post-transplant lymphoproliferative diseases (PTLD) following allogeneic hematopoietic stem cell transplantation are extremely rare. We can successfully treat an EBV-associated leukemic lymphoma patient with rituximab, cidofovir, and donor lymphocyte infusion (DLI). In the present case, EBV-specific T cells that were present in the peripheral blood before rituximab administration treatment rapidly increased after DLI in association with a decrease in the EBV-DNA load.

Epstein-Barr virus load in transplant patients: Early detection of post-transplant lymphoproliferative disorders

High levels of circulating EBV load are used as a marker of post-transplant lymphoproliferative disorders (PTLD). There is no consensus regarding the threshold level indicative of an increase in peripheral EBV DNA. The aim of the study was to clinically validate a developed EBV quantification assay for early PTLD detection. Transversal study: paired peripheral blood mononuclear cells (PBMC), plasma and oropharyngeal lymphoid tissue (OLT) from children undergoing a solid organ transplant with (n=58) and without (n=47) PTLD. Retrospective follow-up: 71 paired PBMC and plasma from recipients with (n=6) and without (n=6) PTLD history. EBV load was determined by real-time PCR. The diagnostic ability to detect all PTLD (categories 1-4), advanced PTLD (categories 2-4) or neoplastic PTLD (categories 3 and 4) was estimated by analyzing the test performance at different cut-off values or with a load variation greater than 0.5log units. The higher diagnostic performance for identifying all, advanced or neoplastic PTLD, was achieved with cut-off values of 1.08; 1.60 and 2.47log EBVgEq/10(5) PBMC or 2.30; 2.60; 4.47loggEq/10(5) OLT cells, respectively. EBV DNA detection in plasma showed high specificity but low (all categories) or high (advanced/neoplastic categories) sensitivity for PTLD identification. Diagnostic performance was greater when: (1) a load variation in PBMC or plasma was identified; (2) combining the measure of EBV load in PBMC and plasma. The best diagnostic ability to identify early PTLD stages was achieved by monitoring EBV load in PBMC and plasma simultaneously; an algorithm was proposed.

Automated quantification of Epstein-Barr Virus in whole blood of hematopoietic stem cell transplant patients using the Abbott m2000 system

BACKGROUND

Accurate quantification of Epstein-Barr virus (EBV) load in blood is essential for the management of post-transplant lymphoproliferative disorders. The automation of DNA extraction and amplification may improve accuracy and reproducibility. We evaluated the EBV PCR Kit V1 with fully automated DNA extraction and amplification on the m2000 system (Abbott assay).

METHODOLOGY

Conversion factor between copies and international units (IU), lower limit of quantification, imprecision and linearity were determined in a whole blood (WB) matrix. Results from 339 clinical WB specimens were compared with a home-brew real-time PCR assay used in our laboratory (in-house assay).

RESULTS

The conversion factor between copies and IU was 3.22 copies/IU. The lower limit of quantification (LLQ) was 1000 copies/mL. Intra- and inter-assay coefficients of variation were 3.1% and 7.9% respectively for samples with EBV load higher than the LLQ. The comparison between Abbott assay and in-house assay showed a good concordance (kappa = 0.77). Loads were higher with the Abbott assay (mean difference = 0.62 log10 copies/mL).

SIGNIFICANCE

The EBV PCR Kit V1 assay on the m2000 system provides a reliable and easy-to-use method for quantification of EBV DNA in WB.

The clinical significance of EBV DNA in the plasma and peripheral blood mononuclear cells of patients with or without EBV diseases

Epstein-Barr virus (EBV) is a ubiquitous virus that establishes a latent infection within the host and in some cases can lead to the development of EBV-associated lymphomas, lymphoproliferative disorders, hemophagocytic lymphohistiocytosis, solid tumors, and other diseases. We studied the clinical significance of detecting EBV DNA in the plasma and peripheral blood mononuclear cells (PBMCs) of 2146 patients who had blood specimens sent to the Johns Hopkins Hospital clinical laboratory for viral quantitative real-time polymerase chain reaction assay over a 5-year period. Within this largely immunocompromised and hospitalized cohort, 535 patients (25%) had EBV detected in plasma or PBMCs. When EBV was detected in the absence of an EBV(+)disease (n = 402), it was present only in PBMCs in 69% of cases. Immunocompromised patients were less likely to have EBV in plasma than in PBMCs in the absence of EBV(+)disease. In patients with active, systemic EBV(+)diseases (n = 105), EBV was detected in plasma in 99% of cases but detected in PBMCs in only 54%. Across a range of copy number cutoffs, EBV in plasma had higher specificity and sensitivity for EBV(+)disease as compared with EBV in PBMCs. EBV copy number in plasma distinguished untreated, EBV(+)lymphoma from EBV(+)lymphoma in remission and EBV(-)lymphoma, and also distinguished untreated, EBV(+)posttransplantation lymphoproliferative disorder (PTLD) from EBV(+)PTLD in remission and EBV(-)PTLD. EBV copy number quantification is a useful diagnostic marker across the spectrum of EBV(+)diseases, even among immunocompromised patients, with plasma specimens more indicative of EBV(+)disease than PBMCs.

ATM facilitates mouse gammaherpesvirus reactivation from myeloid cells during chronic infection

Gammaherpesviruses are cancer-associated pathogens that establish life-long infection in most adults. Insufficiency of Ataxia-Telangiectasia mutated (ATM) kinase leads to a poor control of chronic gammaherpesvirus infection via an unknown mechanism that likely involves a suboptimal antiviral response. In contrast to the phenotype in the intact host, ATM facilitates gammaherpesvirus reactivation and replication in vitro. We hypothesized that ATM mediates both pro- and antiviral activities to regulate chronic gammaherpesvirus infection in an immunocompetent host. To test the proposed proviral activity of ATM in vivo, we generated mice with ATM deficiency limited to myeloid cells. Myeloid-specific ATM deficiency attenuated gammaherpesvirus infection during the establishment of viral latency. The results of our study uncover a proviral role of ATM in the context of gammaherpesvirus infection in vivo and support a model where ATM combines pro- and antiviral functions to facilitate both gammaherpesvirus-specific T cell immune response and viral reactivation in vivo.

Post-transplant lymphoproliferative disorders: from epidemiology to pathogenesis-driven treatment

Post-transplant lymphoproliferative disorders (PTLDs) represent the most severe complication of both solid organ and hematopoietic stem cell transplantation. The Epstein-Barr Virus (EBV) is the main driver of PTLD, particularly those occurring early after transplantation. EBV-driven malignancies are associated with selective expression of latent viral proteins, but uncontrolled lytic replication may favor early phases of cell transformation. Besides immunodepression, persistent immune activation and chronic inflammation play an important role in both virus reactivation and expansion of EBV-infected B cells. EBV-induced immortalization requires the expression of telomerase. TERT, the rate-limiting component of the telomerase complex, is central in the switch from the lytic to the latent viral program, and TERT inhibition induces the EBV lytic cycle and cell death. Immunotherapy and combination of EBV lytic cycle inducers with antiviral drugs are promising strategies to improve the treatment of PTLD patients. This review is aimed at providing an update on the intriguing association between EBV and PTLD, mainly focusing on cases arising after kidney and liver transplantation, which account for the vast majority of transplants.

The Biology and Clinical Utility of EBV Monitoring in Blood

Epstein-Barr virus (EBV) DNA in blood can be quantified in peripheral blood mononuclear cells, in circulating cell-free (CCF) DNA specimens, or in whole blood. CCF viral DNA may be actively released or extruded from viable cells, packaged in virions or passively shed from cells during apoptosis or necrosis. In infectious mononucleosis, viral DNA is detected in each of these kinds of specimens, although it is only transiently detected in CCF specimens. In nasopharyngeal carcinoma, CCF EBV DNA is an established tumor marker. In EBV-associated Hodgkin lymphoma and in EBV-associated extranodal NK-/T-cell lymphoma, there is growing evidence for the utility of CCF DNA as a tumor marker.

Comparison of different rabbit ATG preparation effects on early lymphocyte subset recovery after allogeneic HSCT and its association with EBV-mediated PTLD

PURPOSE

Rabbit antithymocyte globulin (ATG) is commonly used before allogeneic hematopoietic stem cell transplantation (allo-HSCT) to prevent graft-versus-host disease. Studies comparing the effect of different ATG preparations and dosages on immune reconstitution and risk for Epstein-Barr virus (EBV)-mediated post-transplant lymphoproliferative disorder (PTLD) are rare.

METHODS

In this retrospective study, we determined T and B cell subsets by flow cytometry after allo-HSCT in children, who received ATG-Genzyme (ATG-G, n = 15), ATG-Fresenius (ATG-F, n = 25) or no-ATG treatment (n = 19). Additionally, PCR-quantified EBV-genome copy counts were correlated with incidence of PTLD.

RESULTS

We could confirm a dose-dependent impairment of CD8(+) and CD4(+) T cell regeneration by ATG-G, including naïve and memory CD4(+) T cells. No differences were seen between the currently applied dosages of 5-10 mg/kg ATG-G and 20-60 mg/kg ATG-F. Significantly delayed T cell subset reconstitution was determined only at high dosages of 20-60 mg/kg ATG-G compared to ATG-F. B cell reconstitution was comparably impaired in ATG-G- and ATG-F-treated patients. Although the incidence of EBV reactivation was similar in both ATG groups, EBV copy counts of >10(4) copies/10(5) peripheral blood mononuclear cells and the occurrence of PTLD were only found in ATG-G-treated patients.

CONCLUSIONS

We conclude that high, but importantly not currently applied low dosages of ATG-G, impair thymic T cell regeneration and memory T cell immunity to a greater extent than ATG-F in pediatric patients. In addition, our results suggest an increased risk for EBV-PTLD when treated with ATG-G. Prospective studies are warranted to compare different ATG preparations with regard to the immune reconstitution and EBV-PTLD.

Duplex realtime PCR method for Epstein-Barr virus and human DNA quantification: its application for post-transplant lymphoproliferative disorders detection

INTRODUCTION

The quantification of circulating Epstein-Barr virus (EBV) DNA is used to monitor transplant patients as an early marker of Post-Transplant Lymphoproliferative Disorders (PTLD). So far no standardized methodology exists for such determination.

OBJECTIVE

Our purpose was to develop and validate a real-time PCR assay to quantify EBV DNA in clinical samples from transplant recipients.

METHODS

A duplex real-time PCR method was developed to amplify DNA from EBV and from a human gene. The EBV load was determined in peripheral blood mononuclear cells (PBMC), plasma and oropharyngeal tissue from 64 non-transplanted patients with lymphoid-hypertrophy (Non-Tx), 47 transplant recipients without PTLD (Tx), 54 recipients with PTLD (Tx-PTLD), and 66 blood donors (BD). WinPEPI, version 11.14 software was used for statistical analysis.

RESULTS

Analytical validation: the intra and inter-assays variation coefficients were less than 4.5% (EBV-reaction) and 3% (glyceraldehyde 3-phosphate dehydrogenase - GAPDH reaction). Linear ranges comprised 10(7)-10 EBV genome equivalents (gEq) (EBV-reaction) and 500,000-32 human gEq (GAPDH-reaction). The detection limit was 2.9 EBV gEq (EBV-reaction). Both reactions showed specificity. Application to clinical samples: higher levels of EBV were found in oropharyngeal tissue from transplanted groups with and without PTLD, compared to Non-Tx (p<0.05). The EBV load in PBMC from the groups of BD, Non-Tx, Tx and Tx-PTLD exhibited increasing levels (p<0.05). In BD, PBMC and plasma, EBV loads were undetectable.

CONCLUSIONS

The performance of the assay was suitable for the required clinical application. The assay may be useful to monitor EBV infection in transplant patients, in particular in laboratories from low-income regions that cannot afford to use commercial assays.

Advances in the management of viral infections

Viral infections are common in cancer patients. The risk and severity of infection are influenced by patient, disease, treatment, and viral factors. Severe viral infections are more likely to occur in treatment regimens that are more immunosuppressive. Historically, the most frequent severe infections have been due to herpesviruses, but more recently, other pathogens, especially community respiratory and hepatitis viruses, have received increasing attention as major viral pathogens in cancer patients. Because of the new diagnostic assays and the introduction of better therapeutic options, knowledge of viral infections is important in optimizing antineoplastic therapies.

Determining EBV load: current best practice and future requirements

EBV, a gammaherpesvirus and the pathogenic agent for infectious mononucleosis, is also associated with a broad spectrum of lymphoid and epithelial malignancies in immunocompetent and immunosuppressed individuals. EBV-DNA-load measurement by PCR has been shown to be a potential tool for the diagnosis of these diseases, a prognostic factor of their outcome and a successful method to monitor immunosuppressed patients. Since the end of 2011, there is an international WHO standard reference for EBV quantification available; however, many questions still remain; for instance about the optimal amplified region of the EBV genome, or the best-used specimen for EBV detection. Additionally, the optimal specimen and amplified region may vary in different malignancies. In this article, the authors review the different methods to measure EBV load, focus on the best-used specimen for the different EBV-associated malignancies and discuss future requirements and opportunities for EBV-load measurement.

Is there diagnostic value in detection of immunoglobulin g antibodies to the epstein-barr virus early antigen?

The Epstein-Barr virus early antigen (EBV EA) complex consists of multiple proteins with potential significance for diagnosis of EBV-related diseases. In many individuals, detection of antibody to the early antigen (EA) is a sign of active infection, but 20% of healthy people may have this antibody for years. We studied the role of EA immunoglobulin G (IgG) in individuals with atypical antibody responses in the diagnosis of infectious mononucleosis (IM) and in EBV-infected transplant patients. EA IgG was present in 72% of confirmed IM patients. A trend was observed between high viral loads and the presence of EA IgG and between low viral loads and the absence of EA IgG in EBV-associated disease negative liver transplant recipients. Three assays that measure serum EA IgG were compared; enzyme-linked immunosorbent assay (ELISA), chemiluminescent immunoassay (CLIA), and immunoblot assay. The automated CLIA was found to be more accurate than the ELISA when using the immunoblot assay as a "gold standard" assay in the detection of EA IgG. There may be a potential role for EA IgG testing, together with EBV viral load, in the prediction of transplant recipients at risk of EBV-associated disease; however, EA IgG does not play a significant role in the differential diagnosis of EBV infection in immunocompetent individuals.

Prevention of Infections in Patients with Hematological Malignancies

Infection is a frequent complication and a leading cause of morbidity and mortality in patients with hematological malignancies. Problems associated with the management of infections in these patients include difficulties in early diagnosis because the clinical signs of infection are subtle, the low performance of diagnostic tests, and suboptimal response to treatment because recovery of host defenses is a key factor for resolution of infection. Preventing these infections relies on infection control measures and antimicrobial chemoprophylaxis. While infection control measures are safe (but not always effective), the use of antimicrobial agents for prophylaxis of infection is not devoid of problems. Its wide use may increase the possibility of the development of resistance, select for resistant organisms, and increase toxicity and cost. Therefore, any attempt to administer an antimicrobial agent should be accompanied by a reflection of the potential benefits and risks of prophylaxis.

Epstein-Barr virus: general factors, virus-related diseases and measurement of viral load after transplant

The Epstein-Barr virus is responsible for infectious mononucleosis syndrome and is also closely associated to several types of cancer. The main complication involving Epstein-Barr virus infection, both in recipients of hematopoietic stem cells and solid organs, is post-transplant lymphoproliferative disease. The importance of this disease has increased interest in the development of laboratory tools to improve post-transplant monitoring and to detect the disease before clinical evolution. Viral load analysis for Epstein-Barr virus through real-time polymerase chain reaction is, at present, the best tool to measure viral load. However, there is not a consensus on which sample type is the best for the test and what is its predictive value for therapeutic interventions.

Quantitative Epstein-Barr virus shedding and its correlation with the risk of post-transplant lymphoproliferative disorder

We postulated that quantitative monitoring of Epstein-Barr virus (EBV) shedding after transplantation could distinguish EBV-associated illnesses and predict clinical outcome. EBV DNA was measured in solid organ (SOT) and hematopoietic cell transplants (HCT) using our own real-time TaqMan EBV PCR. The proportion of patients who had EBV DNAemia post-transplant was significantly lower in HCT vs. SOT (p < 0.001). Over a 7.5-yr period, post-transplant lymphoproliferative disorder (PTLD) occurred in 66 (5.8%) of 1131 patients who met adequate monitoring criteria. SOT recipients developed PTLD significantly later than HCT recipients (median, 2.8 yr vs. 121 d; p < 0.001). PTLD was documented in 53 (14%) of 376 patients who had EBV in ≥1 whole blood sample vs. 13 (2%) of 755 patients who had at least three EBV-negative blood samples and were never positive. PTLD risk in viremic patients increased with the peak quantity of EBV DNAemia (p < 0.001). PTLD occurred in 37/333 (11%) of patients with peak blood levels 10(3) -10(5) copies/mL vs. 16/43 (37%) of patients with levels >10(5) (p < 0.001). EBV PCR was predictive in 29 (78%) of 37 patients tested within three wk prior to tissue diagnosis of PTLD, and thus, we conclude that EBV PCR with careful attention paid to changes in EBV DNAemia could lead to earlier diagnosis and treatment of PTLD.

Natural and adoptive T-cell immunity against herpes family viruses after allogeneic hematopoietic stem cell transplantation

Reactivated infections with herpes family-related cytomegalovirus, Epstein-Barr virus and varicella zoster virus are serious and sometimes life-threatening complications for patients undergoing allogeneic hematopoietic stem cell transplantation. The pathogenesis of these infections critically involves the slow and inefficient recovery of antiviral T-cell immunity after transplantation. Although efficient drugs to decrease viral load during this vulnerable period have been developed, long-term control of herpes viruses and protection from associated diseases require the sufficient reconstitution of virus-specific memory T cells. To heal the deficiency by immunotherapeutic means, numerous research groups have developed antiviral vaccines and strategies based on the adoptive transfer of virus-specific T cells. This article summarizes the substantial progress made in this field during the past two decades and gives future perspectives about challenges that need to be addressed before antigen-specific immunotherapy against herpes family viruses can be implemented in general clinical practice.

Comparison of six different specimen types for Epstein-Barr viral load quantification in peripheral blood of pediatric patients after heart transplantation or after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Epstein-Barr Virus (EBV) a gamma-herpes virus is associated with a spectrum of lymphoid and epithelial malignancies including posttransplant lymphoproliferative disorders (PTLD). EBV-load measurement has been shown to be important for the monitoring of these patients. However, in contrast to the viral quantification of human immunodeficiency virus or human hepatitis C virus, the EBV-load measurement has not been completely standardized as yet.

OBJECTIVES

In this study, we compared the EBV DNA levels in whole blood (WB), plasma, peripheral mononuclear cells (PBMC) and B-cells (BC) in children and adolescents after heart transplantations (HTx) and allogeneic hematopoietic stem cell transplantations (HSCT).

STUDY DESIGN

In a period of 2 years (from May 2007 to May 2009) we collected 547 samples of 96 cardiac transplant recipients and 248 samples of 37 patients who underwent HSCT. For EBV DNA quantification we used a duplex real-time PCR (ABI Prism 7500, Applied Biosystems). Additionally, EBV-load of PBMC and BC were normalized with respect to endogenous cell DNA.

RESULTS

In both patient populations we found no significant difference of test sensitivity for the EBV detection. In PBMC as well as BC, there was a high correlation between the analysis of cells with and without normalization in both populations. Spearman's correlation coefficient ρ between PBMC without and PBMC with normalization was ρ=0.98 (P<0.0001) in patients after HTx and ρ=0.99 (P<0.0001) in patients after HSCT. Correlation between BC with and without normalization was ρ=0.98 (P<0.0001) in patients after HTx and ρ=0.995 (P<0.0001) in patients after HSCT. When comparing the different blood compartments for EBV quantification in both populations, the strongest correlations were found between the EBV DNA levels in WB and PBMC (HTx: ρ=0.93, P<0.0001; HSCT: ρ=0.81, P<0.0001) followed by PBMC and BC (HTx: ρ=0.87, P<0.0001; HSCT: ρ=0.81, P<0.0001) as well as WB and BC (HTx: ρ=0.86, P<0.0001; HSCT: ρ=0.75, P<0.0001). In contrast, the correlation coefficients between plasma and the other blood compartments (WB as well as PBMC or BC) were lower. Six patients developed seven episodes of PTLD (five patients after HTx and one after renal transplantation). Analyzing the different blood compartments, we found that a threshold of WB ≥20,000EBV-copies/ml and plasma ≥1000EBV-copies/ml had the highest sensitivities and specificities (WB: sensitivity 100%, specificity 87% and plasma: sensitivity 88%, specificity 98%).

CONCLUSION

Normalization towards an endogenous control does not seem to be necessary for EBV quantification in peripheral blood. The analysis of whole blood correlates well with B-cells and PBMC. Routine screening of EBV DNA in whole blood appeared to be a useful tool supplemented by EBV-load measurement in plasma to discriminate chronic high EBV-load carrier without risk for PTLD from those who are at risk for PTLD. Values in whole blood higher than 20,000EBV-copies/ml WB and plasma values higher than 1000EBV-copies/ml plasma indicated PTLD in our series.

Progress and problems in understanding and managing primary Epstein-Barr virus infections

Epstein-Barr virus (EBV) is a gammaherpesvirus that infects a large fraction of the human population. Primary infection is often asymptomatic but results in lifelong infection, which is kept in check by the host immune system. In some cases, primary infection can result in infectious mononucleosis. Furthermore, when host-virus balance is not achieved, the virus can drive potentially lethal lymphoproliferation and lymphomagenesis. In this review, we describe the biology of EBV and the host immune response. We review the diagnosis of EBV infection and discuss the characteristics and pathogenesis of infectious mononucleosis. These topics are approached in the context of developing therapeutic and preventative strategies.

The clinical value of concomitant Epstein Barr virus (EBV)-DNA load and specific immune reconstitution monitoring after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Monitoring of EBV DNAemia after allogeneic hematopoietic stem cell transplantation (HSCT) is necessary, but not sufficient, to identify patients at risk of EBV-induced post-transplantation lymphoproliferative disorders (PTLD). Combining this with quantifying EBV-specific cellular immunity was shown to be helpful. In this study, we evaluated the value of IFNγ-Elispot assay in monitoring EBV DNAemia after HSCT.

METHODS

EBV-DNA load in whole blood was monitored at least weekly using real-time PCR in 40 recipients of HSCT. Quantitative and qualitative T-cell recoveries, including EBV-specific T-cell quantification by Elispot assay, were studied 60, 100, 180 and 360 days after HSCT.

RESULTS

Among the 35 evaluable patients, 14 (35%) presented EBV DNAemia, only 2/14 (14%) needing pre-emptive treatment with rituximab. The greatest risk factor for EBV DNAemia was the presence of anti-thymocyte globulin (ATG) (p=0.005). EBV-specific cellular immune recovery was monitored by IFNγ-Elispot assay. Using multivariate analysis, four factors were found to significantly influence IFNγ-Elispot results at defined times post-HSCT: EBV DNAemia, young age, global T-cell recovery and severe acute GVHD. In those cases where EBV DNAemia occurred and cleared spontaneously, Elispot results gave more than 1000 spot-forming cells (SFC)/10(6)PBMC.

CONCLUSION

Elispot assay may be usefully combined with EBV-DNA load monitoring to determine when a patient should receive pre-emptive treatment, or when the clinician should avoid Rituximab use which severely immunocompromises patients.

Epstein-Barr virus infections after allogeneic stem cell transplantation: a comparison between non-malignant and malignant hematological disorders

Hematological cancers and non-malignant hematological disorders are biologically diverse conditions and are treated differently. We compared the pattern of EBV infections following allogeneic stem cell transplantation between the above two groups of hematological disorders. Eighty-three transplants were evaluated over a consecutive 7-year period at a single center. No difference was found in the incidence of post-transplant EBV infections between the two groups, though a higher median peak viral load was noted in the non-malignant group (P=0·04). Pre-transplant immunosuppressive therapy with antithymocyte globulin (ATG) significantly increased the risk of post-transplant EBV infections (P=0·04) in the non-malignant group patients. No significance was found for prior cytotoxic chemotherapy among the malignant group of patients. Alemtuzumab based conditioning was not associated with an increased risk for EBV infections in either of the groups. Treatment with two or more courses of ATG was found to be significantly associated with post-transplant EBV-related PTLD (P=0·01). Post-transplant EBV infections did not influence overall survival (non-malignant, P=0·66; malignant, P=0·41) in either of the subgroups. There were no deaths directly attributable to EBV infections.

Detection and quantitation of Epstein-Barr virus (EBV) DNA in EDTA whole blood samples using automated sample preparation and real time PCR

BACKGROUND

Detection and quantitation of Epstein-Barr virus (EBV) DNA in EDTA whole blood samples has gained significance in the routine diagnostic laboratory.

METHODS

In this study, the analytical and clinical performance of the artus EBV RG PCR kit in conjunction with automated sample preparation on the QIAsymphony SP instrument was evaluated.

RESULTS

When the accuracy of the new test system was tested, all results were found to be within +/-0.5 log(10) unit of the expected panel results. Determination of linearity showed a quasilinear curve over 4 log units. The lower limit of detection was determined to be 391 EBV DNA copies/mL in EDTA whole blood. The between day imprecision ranged from 18% to 66%, and the within run imprecision ranged from 11% to 50%. When clinical samples were tested and the results compared with those obtained with the routinely used easyMAG sample preparation and EBV R-gene test system, 60 samples tested positive and 31 samples tested negative by both assays. Nineteen samples were found to be positive using the QIAsymphony sample preparation and artus EBV RG PCR test system only, and no samples tested positive with the routinely used test system only.

CONCLUSIONS

The QIAsymphony sample preparation and artus EBV RG PCR test system is suitable for the detection and quantitation of EBV DNA in EDTA whole blood in the routine diagnostic laboratory.