Screening for adenoviruses in haematological neoplasia: High prevalence in mantle cell lymphoma

E4orf1: The triple agent of adenovirus - Unraveling its roles in oncogenesis, infectious obesity and immune responses in virus replication and vector therapy

Human Adenoviruses (HAdV) are nearly ubiquitous pathogens comprising numerous sub-types that infect various tissues and organs. Among many encoded proteins that facilitate viral replication and subversion of host cellular processes, the viral E4orf1 protein has emerged as an intriguing yet under-investigated player in the complex interplay between the virus and its host. E4orf1 has gained attention as a metabolism activator and oncogenic agent, while recent research is showing that E4orf1 may play a more important role in modulating cellular pathways such as PI3K-Akt-mTOR, Ras, the immune response and further HAdV replication stages than previously anticipated. In this review, we aim to explore the structure, molecular mechanisms, and biological functions of E4orf1, shedding light on its potentially multifaceted roles during HAdV infection, including metabolic diseases and oncogenesis. Furthermore, we discuss the role of functional E4orf1 in biotechnological applications such as Adenovirus (AdV) vaccine vectors and oncolytic AdV. By dissecting the intricate relationships between HAdV types and E4orf1 proteins, this review provides valuable insights into viral pathogenesis and points to promising areas of future research.

Advances of Recombinant Adenoviral Vectors in Preclinical and Clinical Applications

Adenoviruses (Ad) have the potential to induce severe infections in vulnerable patient groups. Therefore, understanding Ad biology and antiviral processes is important to comprehend the signaling cascades during an infection and to initiate appropriate diagnostic and therapeutic interventions. In addition, Ad vector-based vaccines have revealed significant potential in generating robust immune protection and recombinant Ad vectors facilitate efficient gene transfer to treat genetic diseases and are used as oncolytic viruses to treat cancer. Continuous improvements in gene delivery capacity, coupled with advancements in production methods, have enabled widespread application in cancer therapy, vaccine development, and gene therapy on a large scale. This review provides a comprehensive overview of the virus biology, and several aspects of recombinant Ad vectors, as well as the development of Ad vector, are discussed. Moreover, we focus on those Ads that were used in preclinical and clinical applications including regenerative medicine, vaccine development, genome engineering, treatment of genetic diseases, and virotherapy in tumor treatment.

CAR virus receptor mediates erythroid differentiation and migration and is downregulated in MDS

Myelodysplastic syndromes (MDS) are myeloid neoplasms presenting with dysplasia in the bone marrow (BM) and peripheral cytopenia. In most patients anemia develops. We screened for genes that are expressed abnormally in erythroid progenitor cells (EP) and contribute to the pathogenesis of MDS. We found that the Coxsackie-Adenovirus receptor (CAR = CXADR) is markedly downregulated in CD45low/CD105+ EP in MDS patients compared to control EP. Correspondingly, the erythroblast cell lines HEL, K562, and KU812 stained negative for CAR. Lentiviral transduction of the full-length CXADR gene into these cells resulted in an increased expression of early erythroid antigens, including CD36, CD71, and glycophorin A. In addition, CXADR-transduction resulted in an increased migration against a serum protein gradient, whereas truncated CXADR variants did not induce expression of erythroid antigens or migration. Furthermore, conditional knock-out of Cxadr in C57BL/6 mice resulted in anemia and erythroid dysplasia. Finally, decreased CAR expression on EP was found to correlate with high-risk MDS and decreased survival. Together, CAR is a functionally relevant marker that is down-regulated on EP in MDS and is of prognostic significance. Decreased CAR expression may contribute to the maturation defect and altered migration of EP and thus their pathologic accumulation in the BM in MDS.

Adenovirus persistence, reactivation, and clinical management

Adenoviral infections continue posing a major threat in severely immunocompromised patients including particularly allogeneic stem cell transplant recipients. Although exogenous infections occur in some instances, the majority of invasive events appear to arise from viral reactivation. In the pediatric setting, adenoviruses were demonstrated to persist in the gastrointestinal tract, and the intestinal epithelium serves as the main site of viral replication preceding invasive infection. Regular monitoring of serial stool samples for the presence and load of adenoviruses has therefore become a routine diagnostic tool for post-transplant patient surveillance, and can serve as a trigger for early initiation of treatment. In the adult setting, the source of infection or reactivation is less clear, and monitoring of peripheral blood specimens is the predominant approach for patient surveillance. Timely initiation of antiviral treatment is reportedly required for prevention or successful control of disseminated disease mediated by adenoviruses, and appropriate diagnostic monitoring is therefore of paramount importance. Currently available antiviral agents and immune therapeutic approaches have not been able to entirely overcome the life-threatening courses of invasive adenoviral infections in the immunocompromised clinical setting.

Infections with DNA Viruses, Adenovirus, Polyomaviruses, and Parvovirus B19 in Hematopoietic Stem Cell Transplant Recipients and Patients with Hematologic Malignancies

Infections due to adenovirus, polyomaviruses (BK and JC viruses), and parvovirus B19 may not be as common as infections due to other DNA viruses, such as cytomegalovirus in patients with hematological malignancies and the recipients of hematopoietic stem cell transplantation. However, these infections may result in life-threatening diseases that significantly impact patients' recovery, morbidity, and mortality. Treating physicians should be aware of the diseases associated with these viruses, the patient populations at increased risk for complications due to these infections, and the available diagnostic and therapeutic approaches.

Management of adenovirus infection in patients after haematopoietic stem cell transplantation: State-of-the-art and real-life current approach: A position statement on behalf of the Infectious Diseases Working Party of the European Society of Blood and Marrow Transplantation

The important insights gained over the past years in diagnosis and treatment of invasive adenoviral infections provide new paradigms for the monitoring and clinical management of these life-threatening complications. A meeting was held to discuss and subsequently disseminate the current advances in our understanding of the aetiology/pathogenesis and future treatment options facilitating effective control or prevention of adenovirus-related diseases in the allogeneic haematopoietic stem cell transplant setting. Invited experts in the field discussed recent progress with leading members of the Infectious Diseases Working Party of the European Society of Blood and Marrow Transplantation at the "State-of-the-art" Meeting in Poznan, Poland, in October 2017. In this review article, the panel of experts presents a concise summary of the current evidence based on published data from the last 15 years and on recent achievements resulting from real-life practice. The present position statement reflects an expert opinion on current approaches to clinical management of adenovirus infections in patients undergoing allogeneic haematopoietic stem cell transplant and provides graded recommendations of the panel for diagnostic approaches and preemptive therapy reflecting the present state of knowledge.

Humanized Mice Reproduce Acute and Persistent Human Adenovirus Infection

Severe human adenovirus (HAdV) infections are an increasing threat for immunosuppressed individuals, particularly those who have received stem cell transplants. It has been previously hypothesized that severe infections might be due to reactivation of a persistent infection, but this hypothesis has been difficult to test owing to the lack of a permissive in vivo model of HAdV infection. Here we established a humanized mouse model that reproduces features of acute and persistent HAdV infection. In this model, acute infection correlated with high mortality, weight loss, liver pathology, and expression of viral proteins in several organs. In contrast, persistent infection was asymptomatic and led to establishment of HAdV-specific adaptive immunity and expression of early viral genes exclusively in the bone marrow. These findings validate the use of humanized mice to study acute and persistent HAdV infection and strongly suggest the presence of cellular reservoirs in the bone marrow.