Impact of donor and recipient Epstein-Barr Virus serostatus on outcomes of allogeneic hematopoietic cell transplantation: a systematic review and meta-analysis

Prevalence, management, and new treatment modalities of EBV-DNA-emia and EBV-PTLD after allo-HCT: survey of Infectious Diseases Working Party EBMT

The aim of this study was to determine the current approach of EBV-driven post-transplant complications in context of monitoring, diagnosis, prevalence and treatment in EBMT transplant centers. Routine serology testing in patient and donor before HCT is performed in 95.5% centers. Pretransplant EBV-DNA is routinely tested in all patients in 32.7% centers. Monitoring for EBV infection is feasible in 98.2% centers: including 66.7% centers using standardized PCR. Post-HCT regular monitoring is performed in all patients in 80.5% centers. Anti-EBV prophylaxis with rituximab is used in 12.4% centers. Frequency of csEBV-DNA-emia was 7.4% (adults: 6.2%, children: 12.6%). The PCR threshold used to start preemptive treatment was differentiated among centers. Frequency of EBV-PTLD was 1.6% (adults: 1.3%; children: 3.5%). First-line therapy of EBV-driven complications was rituximab and reduction of immunosuppressive therapy. The rate of failure of first-line preemptive treatment was 12.0%. EBV-specific viral-specific T-lymphocytes were available in 46.0% centers. A number of new experimental therapies were given in 28 patients with resistant/refractory PTLD. In conclusion, the prevalence of EBV-DNA-emia and EBV-PTLD over the period 2020-2021 decreased in comparison to historical data. New trends (routine pretransplant screening for EBV-DNA, wider access to VST, new experimental therapies) are being observed in management of EBV infection after allo-HCT.

Exploring the Human Virome: Composition, Dynamics, and Implications for Health and Disease

Humans are colonized by large number of microorganisms-bacteria, fungi, and viruses. The overall genome of entire viruses that either lives on or inside the human body makes up the human virome and is indeed an essential fraction of the human metagenome. Humans are constantly exposed to viruses as they are ubiquitously present on earth. The human virobiota encompasses eukaryotic viruses, bacteriophages, retroviruses, and even giant viruses. With the advent of Next-generation sequencing (NGS) and ongoing development of numerous bioinformatic softwares, identification and taxonomic characterization of viruses have become easier. The viruses are abundantly present in humans; these can be pathogenic or commensal. The viral communities occupy various niches in the human body. The viruses start colonizing the infant gut soon after birth in a stepwise fashion and the viral composition diversify according to their feeding habits. Various factors such as diet, age, medications, etc. influence and shape the human virome. The viruses interact with the host immune system and these interactions have beneficial or detrimental effects on their host. The virome composition and abundance change during the course of disease and these alterations impact the immune system. Hence, the virome population in healthy and disease conditions influences the human host in numerous ways. This review presents an overview of assembly and composition of the human virome in healthy asymptomatic individuals, changes in the virome profiles, and host-virome interactions in various disease states.

Hematopoietic stem cell transplantation and the noncytomegalovirus herpesviruses

Although hematopoietic stem cell transplantation (HSCT) and other cellular therapies have significantly improved outcomes in the management of multiple hematological and nonhematological malignancies, the resulting impairment in humoral and cellular response increases the risk for opportunistic infection as an undesirable side effect. With their ability to establish latent infection and reactivate when the host immune system is at its weakest point, the Herpesviridae family constitutes a significant proportion of these opportunistic pathogens. Despite recent advancements in preventing and managing herpesvirus infections, they continue to be a common cause of significant morbidity and mortality in transplanted patients. Herein, we aim to provide and update on herpesvirus other than cytomegalovirus (CMV) affecting recipients of HSCT and other cellular therapies.

How I prevent viral reactivation in high-risk patients

Preventing viral infections at an early stage is a key strategy for successfully improving transplant outcomes. Preemptive therapy and prophylaxis with antiviral agents have been successfully used to prevent clinically significant viral infections in hematopoietic cell transplant recipients. Major progress has been made over the past decades in preventing viral infections through a better understanding of the biology and risk factors, as well as the introduction of novel antiviral agents and advances in immunotherapy. High-quality evidence exists for the effective prevention of herpes simplex virus, varicella-zoster virus, and cytomegalovirus infection and disease. Few data are available on the effective prevention of human herpesvirus 6, Epstein-Barr virus, adenovirus, and BK virus infections. To highlight the spectrum of clinical practice, here we review high-risk situations that we handle with a high degree of uniformity and cases that feature differences in approaches, reflecting distinct hematopoietic cell transplant practices, such as ex vivo T-cell depletion.

Who is the patient at risk for EBV reactivation and disease: expert opinion focused on post-transplant lymphoproliferative disorders following hematopoietic stem cell transplantation

INTRODUCTION

Post-transplant lymphoproliferative disorders (PTLD) represent a diverse group of diseases. They develop as a consequence of uncontrolled proliferation of lymphoid or plasmacytic cells resulting from T-cell immunosuppression after transplantation of either hematopoietic cells (HCT) or solid organs (SOT), caused mainly by latent Epstein-Barr virus (EBV). The risk for EBV recurrence is dependent on the level of incompetency of the immune system, presented as an impairment of T-cell immunity.

AREAS COVERED

This review summarizes the data on incidence and risk factors of EBV infection in patients after HCT. The median rate of EBV infection in HCT recipients was estimated at 30% after allogeneic and<1% after autologous transplant; 5% in non-transplant hematological malignancies; 30% in SOT recipients. The median rate of PTLD after HCT is estimated at 3%. The most frequently reported risk factors for EBV infection and disease include: donor EBV-seropositivity, use of T-cell depletion, especially with ATG; reduced-intensity conditioning; mismatched family or unrelated donor transplants; and acute or chronic graft-versus-host-disease.

EXPERT OPINION

The major risk factors for EBV infection and EBV-PTLD can be easily identified: EBV-seropositive donor, depletion of T-cells, and the use of immunosuppressive therapy. Strategies for avoiding risk factors include elimination EBV from the graft and improving T-cell function.

Incidence of Common Herpesviruses in Colonic Mucosal Biopsies Following Hematopoietic Stem Cell Transplantation

Intestinal complications are common after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, only scarce data concern herpesvirus incidence in the colonic mucosa post-HSCT. Our purpose was to assess the frequency and clinical significance of cytomegalovirus (CMV), Epstein−Barr virus (EBV), human herpesvirus type 6 (HHV6), and herpes simplex virus (HSV) in the colonic mucosa post-HSCT. The study group included 119 patients of different ages, mostly with leukemias and lymphomas, subjected to allo-HSCT from haploidentical related (48%) or HLA-compatible donors (52%). In total, 155 forceps biopsies of the colonic mucosa were taken in cases of severe therapy-resistant intestinal syndrome post-HSCT. Most samples were taken from the descending, sigmoid, and transverse colon. Intestinal GVHD or local infections were assessed clinically and by histology. EBV, CMV, HSV, and HHV6 were tested in colonic mucosal lysates with commercial PCR assays. HSV was found in <8% of colonic samples, along with high HHV6 and CMV positivity (up to 62% and 35%, respectively) and a higher EBV incidence at 5−6 months post-HSCT (35%). For CMV and EBV, significant correlations were revealed between their rates of detection in blood and colonic mucosa (r = 0.489 and r = 0.583; p < 0.05). No significant relationships were found between the presence of herpesviruses and most patients’ characteristics. EBV positivity in colonic samples was correlated with delayed leukocyte and platelet recovery post-HSCT. Higher EBV frequency in the colonic mucosa was found in deceased patients (56% versus 21%, p = 0.02). The correlations among EBV positivity in the colon, lethality rates and delayed hematopoietic reconstitution suggest some relationship with systemic and local EBV reactivation post-transplant.

Clinical value of plasma and peripheral blood mononuclear cells Epstein–Barr Virus DNA dynamics on prognosis of allogeneic stem cell transplantation

The application of intracellular and extracellular Epstein–Barr virus (EBV) DNA in allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been poorly characterized. We conducted a combined prospective-retrospective study of 300 patients who underwent allo-HSCT between 2016 to 2019 in our center and monitored for EBV DNA within the first year after HSCT. Combining the optimal cut-off value of EBV DNA load (7.3×10⁴ copies/10⁶ cells) in peripheral blood mononuclear cells (PBMCs) and qualitative detection in plasma (400 copies/mL) allowed for the better differentiation of EBV-related posttransplant lymphoproliferative disorders (EBV-PTLD), with increased sensitivity (100%) and specificity (86%), and provided the effective risk stratification of EBV DNA level according to their impact on transplant outcomes. By multivariate analysis, patients with intermediate-level of EBV DNA load (low EBV DNA load in PBMCs or high load in PBMCs but negative in plasma) was associated with superior overall survival (HR 1.92, 95% CI 1.03-3.57, p=0.039) and lower transplant-related mortality (HR 3.35, 95% CI 1.31-8.58, p=0.012) compared to those with high-level (high load in PBMCs and positive in plasma). Notably, high EBV-level group had poor reconstitution of CD4+ and CD8+T cells, and both low and high EBV-level groups showed abnormally increase in IL-10 level within one year. Additionally, patients with peak EBV DNA load in PBMCs during 3-12 months had a higher incidence of chronic graft versus host disease (GVHD) than those within 3 months post transplantation (17.4% vs 13.7%, p=0.029). Collectively, EBV DNA in PBMCs can synergistically predict the risk of EBV-PTLD and GVHD. The intermediate-level of EBV DNA presented in plasma and PBMCs might contribute to a better reconstitution of T cells associated with favorable prognosis of allo-HSCT.