Mouse Adenovirus Type 1 Persistence Exacerbates Inflammation Induced by Allogeneic Bone Marrow Transplantation

Bone marrow transplantation (BMT) recipients are at risk for substantial morbidity and mortality from human adenovirus infections, often in the setting of reactivation of persistent virus. Human adenovirus persistence in mucosal lymphocytes has been described, but specific cellular reservoirs of persistence and effects of persistence on host responses to unrelated stimuli are not completely understood. We used mouse adenovirus type 1 (MAV-1) to characterize persistence of an adenovirus in its natural host and test the hypothesis that persistence increases complications of bone marrow transplantation (BMT). Following intranasal infection of C57BL/6J mice, MAV-1 DNA was detected in lung, mediastinal lymph nodes, and liver during acute infection at 7 days post infection (dpi), and at lower levels at 28 dpi that remained stable through 150 dpi. Expression of early and late viral transcripts was detected in those organs at 7 dpi but not at later time points. MAV-1 persistence was not affected by deficiency of IFN-γ. We detected no evidence of MAV-1 reactivation in vivo following allogeneic BMT of persistently infected mice. Persistent infection did not substantially affect mortality, weight loss, or pulmonary inflammation following BMT. However, T cell infiltration and increased expression of pro-inflammatory cytokines consistent with graft-versus-host disease (GVHD) were more pronounced in livers of persistently infected BMT mice than in uninfected BMT mice. These results suggest that MAV-1 persists in multiple sites without detectable evidence of ongoing replication. Our results indicate that MAV-1 persistence alters host responses to an unrelated challenge, even in the absence of detectable reactivation. Importance Long-term persistence in an infected host is an essential step in the life cycle of DNA viruses. Adenoviruses persist in their host following acute infection, but the nature of adenovirus persistence remains incompletely understood. Following intranasal infection of mice, we found that MAV-1 persists for a prolonged period in multiple organs, although we did not detect evidence of ongoing replication. Because BMT recipients are at risk for substantial morbidity and mortality from human adenovirus infections, often in the setting of reactivation of persistent virus in the recipient, we extended our findings using MAV-1 infection in a mouse model of BMT. MAV-1 persistence exacerbated GVHD-like inflammation following allogeneic BMT, even in the absence of virus reactivation. This novel finding suggests that adenovirus persistence has consequences, and it highlights the potential for a persistent adenovirus to influence host responses to unrelated challenges.

Potential Diagnostic and Prognostic Biomarkers for Adenovirus Respiratory Infection in Children and Young Adults

Human Adenoviruses (HAdV) are known to be potentially associated with strong inflammatory responses and morbidity in pediatric patients. Although most of the primary infections are self-limiting, the severity of clinical presentation, the elevation of the white blood cell count and inflammatory markers often mimic a bacterial infection and lead to an inappropriate use of antibiotics. In infections caused by HAdV, rapid antigen detection kits are advisable but not employed routinely; costs and feasibility of rapid syndromic molecular diagnosis may limit its use in the in-hospital setting; lymphocyte cultures and two-sampled serology are time consuming and impractical when considering the use of antibiotics. In this review, we aim to describe the principal diagnostic tools and the immune response in HAdV infections and evaluate whether markers based on the response of the host may help early recognition of HAdV and avoid inappropriate antimicrobial prescriptions in acute airway infections.

The infectivity of progeny adenovirus in the presence of neutralizing antibody

Human adenoviruses (Ads), common pathogens that cause upper respiratory and gastrointestinal infections, are blocked by neutralizing antibodies (nAbs). However, Ads are not fully eliminated even in hosts with nAbs. In this study, we assessed the infectivity of progeny Ad serotype 5 (Ad5) in the presence of nAb. The infectivity of Ad5 was evaluated according to the expression of the Ad genome and reporter gene. Infection by wild-type Ad5 and Ad5 vector continued to increase until 3 days after infection even in the presence of nAb. We established an assay for determining the infection levels of progeny Ad5 using a sorting system with magnetic beads and observed little difference in progeny Ad5 counts in the presence and absence of nAb 1 day after infection. Moreover, progeny Ad5 in the presence of nAb more effectively infected coxsackievirus and adenovirus receptor (CAR)-positive cells than CAR-negative cells. We investigated the function of fiber proteins, which are the binding partners of CAR, during secondary infection, observing that fibre proteins spread from infected cells to adjacent cells in a CAR-dependent manner. In conclusion, this study revealed that progeny Ad5 could infect cells even in the presence of nAb, differing from the common features of the Ad5 infection cycle. Our findings may be useful for developing new therapeutic agents against Ad infection.

Adenovirus infection among pediatric patients with cancer and in pediatric recipients of hematopoietic stem cell: A multicenter nationwide study

The aim was to evaluate the incidence, clinical course, and outcome of adenoviral infection (AdVI) in pediatric patients diagnosed and treated due to cancer and in pediatric recipients of hematopoietic stem cell. Over a 72-month period, all-in 5599 children with cancer: 2441 patients with hematological malignancy (HM) and 3158 with solid tumors (ST), and 971 patients after transplantation: 741 after allogeneic (allo-HSCT) and 230 after autologous (auto-HSCT) were enrolled into the study. Among cancer patients, 67 episodes of AdVI appeared in 63 (1.1%) children, including 45 (1.8%) with HM and 18 (0.6%; P < .001) with ST. Within transplanted patients, AdVIs were responsible for 88 episodes in 81 (8.3%) children (P < .001), including 78 (10.5%) patients after allo-HSCT and 3 (1.3%) after auto-HSCT. Time to develop AdVI was short, especially after allo-HSCT. The most common clinical manifestation in cancer patients was enteritis diagnosed in 63 (94.0%) cases, while among HSCT recipient asymptomatic adenoviremia was found in 36 (40.9%) cases and the most common clinical manifestation was urinary tract infection. Cancer patients with disseminated disease, as well as HSCT recipients with either asymptomatic viremia or disseminated disease, received antiviral treatment. The most commonly used first-line therapy was cidofovir. None of the cancer patients died due to AdVI, while within HSCT recipients three patients developed disseminated adenoviral disease and died despite antiviral treatment. In cancer patients, AdVIs are rare and associated with very good prognosis even without specific treatment. However, in allo-HSCT recipients, disseminated disease with fatal outcome is more likely to occur.

Severe nonbacterial preseptal cellulitis from adenovirus detected via pooled meta-genomic testing

Preseptal cellulitis is a serious diagnosis that can progress to postseptal cellulitis leading to grave consequences. Clinically, viral and bacterial cellulitis can be indistinguishable from each other. Using rapid DNA/RNA sequencing can be helpful.

Detection of adenovirus hepatitis and acute liver failure in allogeneic hematopoietic stem cell transplant patients

Human adenovirus (HAdV) is an important cause of the common cold and epidemic keratoconjunctivitis in immunocompetent individuals. In immunocompromised patients, HAdV can sometimes cause severe infection such as cystitis, gastroenteritis, pneumonia, encephalitis, hepatitis, or disseminated disease, resulting in significant morbidity and also mortality. In particular, severe cases have been reported in patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Indeed HAdV has been recognized as a pathogen that requires careful monitoring in allo-HSCT patients. While HAdV hepatitis leading to severe acute liver failure is rare, such liver failure progresses rapidly and is often fatal. Unfortunately, HAdV hepatitis has few characteristic symptoms and physical findings, which makes it difficult to promptly confirm and start treatment. We report here four cases of HAdV hepatitis after allo-HSCT and their autopsy findings.

Beyond Cytomegalovirus and Epstein-Barr Virus: a Review of Viruses Composing the Blood Virome of Solid Organ Transplant and Hematopoietic Stem Cell Transplant Recipients

Viral primary infections and reactivations are common complications in patients after solid organ transplantation (SOT) and hematopoietic stem cell transplantation (HSCT) and are associated with high morbidity and mortality. Among these patients, viral infections are frequently associated with viremia. Beyond the usual well-known viruses that are part of the routine clinical management of transplant recipients, numerous other viral signatures or genomes can be identified in the blood of these patients. The identification of novel viral species and variants by metagenomic next-generation sequencing has opened up a new field of investigation and new paradigms. Thus, there is a need to thoroughly describe the state of knowledge in this field with a review of all viral infections that should be scrutinized in high-risk populations. Here, we review the eukaryotic DNA and RNA viruses identified in blood, plasma, or serum samples of pediatric and adult SOT/HSCT recipients and the prevalence of their detection, with a particular focus on recently identified viruses and those for which their potential association with disease remains to be investigated, such as members of the Polyomaviridae, Anelloviridae, Flaviviridae, and Astroviridae families. Current knowledge of the clinical significance of these viral infections with associated viremia among transplant recipients is also discussed. To ensure a comprehensive description in these two populations, individuals described as healthy (mostly blood donors) are considered for comparative purposes. The list of viruses that should be on the clinicians' radar is certainly incomplete and will expand, but the challenge is to identify those of possible clinical significance.

Adenovirus infection and disease in recipients of hematopoietic cell transplantation

PURPOSE OF REVIEW

To provide an update on risk factors associated with adenovirus (ADV) infection in patients after hematopoietic cell transplant (HCT) and on options for ADV monitoring and treatment in the setting of HCT.

RECENT FINDINGS

Among patients undergoing HCT, ADV infection continues to be more common amongst those receiving a T-cell-depleted or graft other than from a matched-related donor. Among children undergoing HCT, reactivation in the gastrointestinal tract appears to be the most common source, and the virus is detectable by quantitative PCR in the stool before it is detectable in the blood. Thus, screening for the virus in the stool of these children may allow for preemptive therapy to reduce mortality. Brincidofovir, although still not approved by any regulatory agency, remains a potential agent for preemptive therapy and for salvage in cases not responding to cidofovir. Rapidly generated off-the-shelf virus-specific T cells may facilitate adoptive cell therapy in populations with a special need and previously not eligible for adoptive cell therapy, such as cord blood recipients.

SUMMARY

ADV infection continues to adversely affect survival in HCT recipients. Screening stool in children and preemptive therapy may reduce mortality. Brincidofovir and adoptive T-cell therapy remain potential options for treatment.

[Adenovirus infections]

Während der Kindheit werden zumeist mehrere Adenovirusinfektionen mit jeweils wechselnden Typen durchgemacht. Das Spektrum der assoziierten Krankheitsbilder reicht von endemischen milden, selbstlimitierenden Infektionen des oberen Respirationstrakts über epidemische Gastroenteritis, Augeninfektionen und Zystitis bis hin zu atypischen Pneumonien und schweren Infektionen innerer Organe. Lebensbedrohlich sind die meisten Adenovirusinfektionen nicht, außer die seltenen Infektionen von Neugeborenen und die allerdings häufigen Infektion von Empfängern hämatopoetischer Stammzellen („disseminierte Erkrankung“).

ATO (Arsenic Trioxide) Effects on Promyelocytic Leukemia Nuclear Bodies Reveals Antiviral Intervention Capacity

Human adenoviruses (HAdV) are associated with clinical symptoms such as gastroenteritis, keratoconjunctivitis, pneumonia, hepatitis, and encephalitis. In the absence of protective immunity, as in allogeneic bone marrow transplant patients, HAdV infections can become lethal. Alarmingly, various outbreaks of highly pathogenic, pneumotropic HAdV types have been recently reported, causing severe and lethal respiratory diseases. Effective drugs for treatment of HAdV infections are still lacking. The repurposing of drugs approved for other indications is a valuable alternative for the development of new antiviral therapies and is less risky and costly than de novo development. Arsenic trioxide (ATO) is approved for treatment of acute promyelocytic leukemia. Here, it is shown that ATO is a potent inhibitor of HAdV. ATO treatment blocks virus expression and replication by reducing the number and integrity of promyelocytic leukemia (PML) nuclear bodies, important subnuclear structures for HAdV replication. Modification of HAdV proteins with small ubiquitin-like modifiers (SUMO) is also key to HAdV replication. ATO reduces levels of viral SUMO-E2A protein, while increasing SUMO-PML, suggesting that ATO interferes with SUMOylation of proteins crucial for HAdV replication. It is concluded that ATO targets cellular processes key to HAdV replication and is relevant for the development of antiviral intervention strategies.

Make Sure You Have a Safety Net: Updates in the Prevention and Management of Infectious Complications in Stem Cell Transplant Recipients

Hematopoietic stem cell transplant recipients are at increased risk of infection and immune dysregulation due to reception of cytotoxic chemotherapy; development of graft versus host disease, which necessitates treatment with immunosuppressive medications; and placement of invasive catheters. The prevention and management of infections in these vulnerable hosts is of utmost importance and a key “safety net” in stem cell transplantation. In this review, we provide updates on the prevention and management of CMV infection; invasive fungal infections; bacterial infections; Clostridium difficile infection; and EBV, HHV-6, adenovirus and BK infections. We discuss novel drugs, such as letermovir, isavuconazole, meropenem-vaborbactam and bezlotoxumab; weigh the pros and cons of using fluoroquinolone prophylaxis during neutropenia after stem cell transplantation; and provide updates on important viral infections after hematopoietic stem cell transplant (HSCT). Optimizing the prevention and management of infectious diseases by using the best available evidence will contribute to better outcomes for stem cell transplant recipients, and provide the best possible “safety net” for these immunocompromised hosts.

Infection prophylaxis and management of viral infection

Viral infections are associated with significant morbidity and mortality in lung transplant recipients. Importantly, several viral infections have been associated with the development of chronic lung allograft dysfunction (CLAD). Community-acquired respiratory viruses (CARV) such as influenza and respiratory syncytial virus (RSV), are frequently associated with acute and chronic rejection. Cytomegalovirus (CMV) remains a significant burden in regards to morbidity and mortality in lung transplant recipients. Epstein-Barr virus (EBV) is mostly involved with the development of post-transplant lymphoproliferative disorder (PTLD), a lymphoid proliferation that occurs in the setting of immunosuppression. On the other hand, the development of direct acting antivirals for hepatitis C virus (HCV) is changing the use of HCV-positive organs in transplantation. In this article we will focus on reviewing common viral infections that have a significant impact on lung transplant recipients looking at epidemiology, prevention and potential treatment.

Examining the Complex Relationship Between Tuberculosis and Other Infectious Diseases in Children

Millions of children are exposed to tuberculosis (TB) each year, many of which become infected with Mycobacterium tuberculosis. Most children can immunologically contain or eradicate the organism without pathology developing. However, in a minority, the organism overcomes the immunological constraints, proliferates and causes TB disease. Each year a million children develop TB disease, with a quarter dying. While it is known that young children and those with immunodeficiencies are at increased risk of progression from TB infection to TB disease, our understanding of risk factors for this transition is limited. The most immunologically disruptive process that can happen during childhood is infection with another pathogen and yet the impact of co-infections on TB risk is poorly investigated. Many diseases have overlapping geographical distributions to TB and affect similar patient populations. It is therefore likely that infection with viruses, bacteria, fungi and protozoa may impact on the risk of developing TB disease following exposure and infection, although disentangling correlation and causation is challenging. As vaccinations also disrupt immunological pathways, these may also impact on TB risk. In this article we describe the pediatric immune response to M. tuberculosis and then review the existing evidence of the impact of co-infection with other pathogens, as well as vaccination, on the host response to M. tuberculosis. We focus on the impact of other organisms on the risk of TB disease in children, in particularly evaluating if co-infections drive host immune responses in an age-dependent way. We finally propose priorities for future research in this field. An improved understanding of the impact of co-infections on TB could assist in TB control strategies, vaccine development (for TB vaccines or vaccines for other organisms), TB treatment approaches and TB diagnostics.

A review of 65 years of human adenovirus seroprevalence

Introduction: Human adenovirus (HAdV)-derived vectors have been used in numerous pre-clinical and clinical trials during the last 40 years. Current research in HAdV-based vaccines focuses on improving transgene immunogenicity and safety. Because pre-existing humoral immunity against HAdV types correlate with reduced vaccine efficacy and safety, many groups are exploring the development of HAdV types vectors with lower seroprevalence. However, global seroepidemiological data are incomplete. Areas covered: The goal of this review is to centralize 65 years of research on (primarily) HAdV epidemiology. After briefly addressing adenovirus biology, we chronical HAdV seroprevalence studies and highlight major milestones. Finally, we analyze data from about 50 studies with respect to HAdVs types that are currently used in the clinic, or are in the developmental pipeline. Expert opinion: Vaccination is among the most efficient tools to prevent infectious disease. HAdV-based vaccines have undeniable potential, but optimization is needed and antivector immunity remains a challenge if the same vectors are to be administrated to different populations. Here, we identify gaps in our knowledge and the need for updated worldwide epidemiological data.

Molecular Evolution of Human Adenovirus (HAdV) Species C

Currently, 88 different Human Adenovirus (HAdV) types are grouped into seven HAdV species A to G. Most types (57) belong to species HAdV-D. Recombination between capsid genes (hexon, penton and fiber) is the main factor contributing to the diversity in species HAdV-D. Noteworthy, species HAdV-C contains so far only five types, although species HAdV-C is highly prevalent and clinically significant in immunosuppressed patients. Therefore, the evolution of species HAdV-C was studied by generating 51 complete genome sequences from circulating strains. Clustering of the whole genome HAdV-C sequences confirmed classical typing results (fifteen HAdV-C1, thirty HAdV-C2, four HAdV-C5, two HAdV-C6). However, two HAdV-C2 strains had a novel penton base sequence and thus were re-labeled as the novel type HAdV-C89. Fiber and early gene region 3 (E3) sequences clustered always with the corresponding prototype sequence but clustering of the E4 region indicated recombination events in 26 out of the 51 sequenced specimens. Recombination of the E1 gene region was detected in 16 circulating strains. As early gene region sequences are not considered in the type definition of HAdVs, evolution of HAdV-C remains on the subtype level. Nonetheless, recombination of the E1 and E4 gene regions may influence the virulence of HAdV-C strains.

Impacts and Challenges of Advanced Diagnostic Assays for Transplant Infectious Diseases

The advanced technologies described in this chapter should allow for full inventories to be made of bacterial genes, their time- and place-dependent expression, and the resulting proteins as well as their outcome metabolites. The evolution of these molecular technologies will continue, not only in the microbial pathogens but also in the context of host-pathogen interactions targeting human genomics and transcriptomics. Their performance characteristics and limitations must be clearly understood by both laboratory personnel and clinicians to ensure proper utilization and interpretation.

Humoral immune response to adenovirus induce tolerogenic bystander dendritic cells that promote generation of regulatory T cells

Following repeated encounters with adenoviruses most of us develop robust humoral and cellular immune responses that are thought to act together to combat ongoing and subsequent infections. Yet in spite of robust immune responses, adenoviruses establish subclinical persistent infections that can last for decades. While adenovirus persistence pose minimal risk in B-cell compromised individuals, if T-cell immunity is severely compromised reactivation of latent adenoviruses can be life threatening. This dichotomy led us to ask how anti-adenovirus antibodies influence adenovirus T-cell immunity. Using primary human blood cells, transcriptome and secretome profiling, and pharmacological, biochemical, genetic, molecular, and cell biological approaches, we initially found that healthy adults harbor adenovirus-specific regulatory T cells (T_regs). As peripherally induced T_regs are generated by tolerogenic dendritic cells (DCs), we then addressed how tolerogenic DCs could be created. Here, we demonstrate that DCs that take up immunoglobulin-complexed (IC)-adenoviruses create an environment that causes bystander DCs to become tolerogenic. These adenovirus antigen loaded tolerogenic DCs can drive naïve T cells to mature into adenovirus-specific T_regs. Our study reveals a mechanism by which an antiviral humoral responses could, counterintuitively, favor virus persistence.

While numerous studies have addressed the cellular and humoral response to primary virus encounters, relatively little is known about the interplay between persistent infections, neutralizing antibodies, antigen-presenting cells, and T-cell responses. Our studies suggests that if adenovirus–antibody complexes are taken up by professional antigen-presenting cells (e.g. dendritic cells), the DCs can generate an environment that causes bystander dendritic cells to become tolerogenic. These tolerogenic dendritic cells favors the creation of adenovirus-specific regulatory T cells. While this pathway likely favors pathogen survival, there may be advantages for the host also.

Human adenovirus infections: update and consideration of mechanisms of viral persistence

PURPOSE OF REVIEW

To provide an update on recent studies of human adenoviral (HAdV) infections and to explore the mechanisms of viral persistence and the role of persistent infection in disseminated disease in immunocompromised patients.

RECENT FINDINGS

Human adenoviruses continue to be a problem in ophthalmology clinics and to cause periodic, limited, global outbreaks of respiratory disease. Ad14p1 remains in worldwide circulation and continues to result in miniepidemics of severe respiratory infections. New variants of Ad4 and Ad7 have emerged in both the United States and Asia. The severity of Ad4 infections in outbreaks appears to depend more on preexisting conditions in patients than on genetically determined, viral virulence factors, in contrast to limited evidence of Ad7 mutations that may convey increased viral pathogenesis. Reactivation of persistent adenovirus infection appears to be the primary source of disseminated infections in immunocompromised patients. New studies suggest that establishment of persistent infection and reactivation are related to variations in interferon-mediated control of viral replication.

SUMMARY

Innate immune responses can create a state of adenoviral persistence, and repression of these host defenses can result in reactivation and dissemination of infection. A better definition of the molecular mechanisms of immune-mediated control of viral replication might lead to new strategies for treatment of HAdV reactivation and dissemination.

Genetic diversity of the human adenovirus species C DNA polymerase

BACKGROUND

Human Adenovirus (HAdV) are responsible for severe infections in hematopoietic stem cells transplant (HSCT) recipient, species C viruses being the most commonly observed in this population. There is no approved antiviral treatment yet. Cidofovir (CDV), a cytidine analog, is the most frequently used and its lipophilic conjugate, brincidofovir (BCV), is under clinical development. These drugs target the viral DNA polymerase (DNA pol). Little is known about the natural polymorphism of HAdV DNA pol in clinical strains.

METHODS

We assessed the inter- and intra-species variability of the whole gene coding for HAdV DNA pol of HAdV clinical strains of species C. The study included 60 species C HAdV (21 C1, 27 C2 and 12 C5) strains isolated from patients with symptomatic infections who had never experienced CDV or BCV treatments and 20 reference strains. We also evaluated the emergence of mutations in thrirteen patients with persistent HAdV infection despite antiviral treatment.

RESULTS

We identified 356 polymorphic nucleotide positions (9.9% of the whole gene), including 102 positions with nonsynonymous mutations (28.0%) representing 8.7% of all amino acids. The mean numbers of nucleotide and amino acid mutations per strain were 23.1 (±6.2) and 5.2 (±2.4) respectively. Most of amino acid substitutions (60.6%) were observed in one instance only. A minority (13.8%) were observed in more than 10% of all strains. The most variable region was the NH2 terminal domain (44.2% of amino acid mutations). Mutations in the exonuclease domain accounted for 27.8%. The binding domains for the terminal protein (TPR), TPR1 and TPR2, presented a limited number of mutations, which were nonetheless frequently observed (62.5% and 58.8% of strains for TPR1 and TPR2, respectively). None of the mutations associated with CDV or BCV resistance were detected. In patients receieving antiviral drugs with persistent HAdV replication, we identified a new mutation in the NH2 terminal region.

CONCLUSIONS

Our study shows a high diversity in HAdV DNA pol sequences in clinical species C HAdV and provides a comprehensive mapping of its natural polymorphism. These data will contribute to the interpretation of HAdV DNA pol mutations selected in patients receiving antiviral treatments.

Co-infection with human polyomavirus BK enhances gene expression and replication of human adenovirus

Immunocompromised patients are susceptible to multiple viral infections. Relevant interactions between co-infecting viruses might result from viral regulatory genes which trans-activate or repress the expression of host cell genes as well as the genes of any co-infecting virus. The aim of the current study was to show that the replication of human adenovirus 5 is enhanced by co-infection with BK polyomavirus and is associated with increased expression of proteins including early region 4 open reading frame 1 and both the large tumor antigen and small tumor antigen. Clinical samples of whole blood and urine from 156 hematopoietic stem cell transplant recipients were tested. We also inoculated adenocarcinomic human alveolar basal epithelial cells with both human adenovirus 5 and BK polyomavirus to evaluate if co-infection of viruses affected their replication. Data showed that adenovirus load was significantly higher in the plasma (mean 7.5 x 10³ ± 8.5 x 10² copies/ml) and urine (mean 1.9 x 10³ ± 8.0 x 10² copies/ml) of samples from patients with co-infections, in comparison to samples from patients with isolated adenovirus infection. In vitro co-infection led to an increased (8.6 times) expression of the adenovirus early region 4 open reading frame gene 48 hours post-inoculation. The expression of the early region 4 open reading frame gene positively correlated with the expression of BK polyomavirus large tumor antigen (r = 0.90, p < 0.0001) and small tumor antigen (r = 0.83, p < 0.001) genes. The enhanced expression of the early region 4 open reading frame gene due to co-infection with BK polyomavirus was associated with enhanced adenovirus, but not BK polyomavirus, replication. The current study provides evidence that co-infection of adenovirus and BK polyomavirus contributes to enhanced adenovirus replication. Data obtained from this study may have significant importance in the clinical setting.

Intestinal Adenovirus Shedding Before Allogeneic Stem Cell Transplantation Is a Risk Factor for Invasive Infection Post-transplant

Human adenoviruses (HAdV) are a major cause of morbidity and mortality in pediatric human stem cell transplant (HSCT) recipients. Our previous studies identified the gastrointestinal tract as a site of HAdV persistence, but the role of intestinal virus shedding pre-transplant for the risk of ensuing invasive infection has not been entirely elucidated. Molecular HAdV monitoring of serial stool samples using RQ-PCR was performed in 304 children undergoing allogeneic HSCT. Analysis of stool and peripheral blood specimens was performed pre-transplant and at short intervals until day 100 post-HSCT. The virus was detected in the stool of 129 patients (42%), and 42 tested positive already before HSCT. The patients displaying HAdV shedding pre-transplant showed a significantly earlier increase of intestinal HAdV levels above the critical threshold associated with high risk of invasive infection (p<0.01). In this subset of patients, the occurrence of invasive infection characterized by viremia was significantly higher than in patients without HAdV shedding before HSCT (33% vs 7%; p<0.0001). The data demonstrate that intestinal HAdV shedding before HSCT confers a greatly increased risk for invasive infection and disseminated disease post-transplant, and highlights the need for timely HAdV monitoring and pre-emptive therapeutic considerations in HSCT recipients.

Community acquired respiratory virus infections in cancer patients-Guideline on diagnosis and management by the Infectious Diseases Working Party of the German Society for haematology and Medical Oncology

Background

Community acquired viruses (CRVs) may cause severe disease in cancer patients. Thus, efforts should be made to diagnose CRV rapidly and manage CRV infections accordingly.

Methods

A panel of 18 clinicians from the Infectious Diseases Working Party of the German Society for Haematology and Medical Oncology have convened to assess the available literature and provide recommendations on the management of CRV infections including influenza, respiratory syncytial virus, parainfluenza virus, human metapneumovirus and adenovirus.

Results

CRV infections in cancer patients may lead to pneumonia in approximately 30% of the cases, with an associated mortality of around 25%. For diagnosis of a CRV infection, combined nasal/throat swabs or washes/aspirates give the best results and nucleic acid amplification based-techniques (NAT) should be used to detect the pathogen. Hand hygiene, contact isolation and face masks have been shown to be of benefit as general infection management. Causal treatment can be given for influenza, using a neuraminidase inhibitor, and respiratory syncytial virus, using ribavirin in addition to intravenous immunoglobulins. Ribavirin has also been used to treat parainfluenza virus and human metapneumovirus, but data are inconclusive in this setting. Cidofovir is used to treat adenovirus pneumonitis.

Conclusions

CRV infections may pose a vital threat to patients with underlying malignancy. This guideline provides information on diagnosis and treatment to improve the outcome.

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Community acquired viral respiratory tract infections can be life-threatening in cancer patients.

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Respiratory virus infections need early and appropriate management to improve outcome and avoid outbreaks.

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This guideline summarises recommendations by the AGIHO on community acquired respiratory viruses in cancer patients.

Immune-Complexed Adenovirus Induce AIM2-Mediated Pyroptosis in Human Dendritic Cells

Human adenoviruses (HAdVs) are nonenveloped proteinaceous particles containing a linear double-stranded DNA genome. HAdVs cause a spectrum of pathologies in all populations regardless of health standards. Following repeat exposure to multiple HAdV types, we develop robust and long-lived humoral and cellular immune responses that provide life-long protection from de novo infections and persistent HAdV. How HAdVs, anti-HAdV antibodies and antigen presenting cells (APCs) interact to influence infection is still incompletely understood. In our study, we used physical, pharmacological, biochemical, fluorescence and electron microscopy, molecular and cell biology approaches to dissect the impact of immune-complexed HAdV (IC-HAdV) on human monocyte-derived dendritic cells (MoDCs). We show that IC-HAdV generate stabilized complexes of ~200 nm that are efficiently internalized by, and aggregate in, MoDCs. By comparing IC-HAdV, IC-empty capsid, IC-Ad2ts1 (a HAdV-C2 impaired in endosomal escape due to a mutation that impacts protease encapsidation) and IC-AdL40Q (a HAdV-C5 impaired in endosomal escape due to a mutation in protein VI), we demonstrate that protein VI-dependent endosomal escape is required for the HAdV genome to engage the DNA pattern recognition receptor AIM2 (absent in melanoma 2). AIM2 engagement induces pyroptotic MoDC death via ASC (apoptosis-associated speck protein containing a caspase activation/recruitment domain) aggregation, inflammasome formation, caspase 1 activation, and IL-1β and gasdermin D (GSDMD) cleavage. Our study provides mechanistic insight into how humoral immunity initiates an innate immune response to HAdV-C5 in human professional APCs.

Performance Characteristics of FilmArray Respiratory Panel v1.7 for Detection of Adenovirus in a Large Cohort of Pediatric Nasopharyngeal Samples: One Test May Not Fit All

The FilmArray Respiratory Panel (RP) v1.7 assay has improved sensitivity for detection of human adenovirus (HAdV), compared to an earlier version (RP v1.6). RP v1.7 was designed for detection of species B, C, and E but may show variable detection of species A, D, and F. We sought to evaluate the clinical and analytical performance of RP v1.7 for detection of HAdV in a large pediatric cohort. Respiratory specimens obtained from a tertiary care children's hospital between February 2014 and February 2015 were tested for HAdV by RP v1.7. If the RP v1.7 results were negative for HAdV, then the specimens were reflexed to a HAdV-specific laboratory-developed PCR (LD-PCR) assay for confirmation. A subset of specimens underwent secondary confirmatory testing using another commercially available HAdV PCR assay and a molecular typing assay for species identification. Among 4,750 specimens, a total of 146 specimens (3.1%) were HAdV positive by RP v1.7. HAdV was detected by LD-PCR in an additional 220 specimens that were negative by RP v1.7. Overall, a nearly 5% increase in HAdV detection was observed when RP v1.7-negative specimens were reflexed to LD-PCR testing. RP v1.7 did not detect HAdV with either low viral burden (threshold cycle values of >30) or nonrespiratory species (species A, D, and F), as shown in both clinical and analytic data. While the level of sensitivity of RP v1.7 may be adequate for testing among otherwise healthy children, the decreased sensitivity may be problematic for immunocompromised patients, in whom low levels of HAdV in the respiratory tract may precede systemic infection and require early intervention.

Pre-Transplant Screening for Latent Adenovirus in Donors and Recipients

Human adenoviruses are frequent cause of slight self-limiting infections in immune competent subjects, while causing life-threatening and disseminated diseases in immunocompromised patients, particularly in the subjects affected by acquired immunodeficiency syndrome and in bone marrow and organ transplant recipients. Here, infections interest lungs, liver, encephalon, heart, kidney and gastro enteric tract. To date, human adenoviruses comprise 51 serotypes grouped into seven species, among which species C especially possesses the capability to persist in infected tissues. From numerous works, it emerges that in the recipient, because of loss of immune-competence, both primary infection, via the graft or from the environment, and reactivated endogenous viruses can be responsible for transplantation related adenovirus disease. The transplants management should include the evaluation of anti-adenovirus pre-transplant screening similar to that concerning cytomegalovirus. The serological screening on cytomegalovirus immunity is currently performed to prevent viral reactivation from grafts and recipient, the viral spread and dissemination to different organs and apparatus, and potentially lethal outcome.

Persistence and reactivation of human adenoviruses in the gastrointestinal tract

Reactivation of persistent human adenoviruses (HAdVs) is associated with high morbidity and mortality in paediatric haematopoietic stem cell transplant (HSCT) recipients. Although invasive HAdV infections mainly arise from the gastrointestinal (GI) tract, the specific sites of HAdV persistence are not well characterised. We prospectively screened biopsies from 143 non-HSCT paediatric patients undergoing GI endoscopy and monitored serial stool specimens from 148 paediatric HSCT recipients for the presence of HAdV by real-time PCR. Persistence of HAdV in the GI tract was identified in 31% of children, with the highest prevalence in the terminal ileum. In situ hybridisation and immunohistochemistry identified HAdV persistence in lymphoid cells of the lamina propria, whereas biopsies from five transplant recipients revealed high numbers of replicating HAdV in intestinal epithelial cells. The prevalence of HAdV species, the frequencies of persistence in the GI tract and reactivations post transplant indicated a correlation of intestinal HAdV shedding pre-transplant with high risk of invasive infection. HAdV persistence in the GI tract is a likely origin of infectious complications in immunocompromised children. Intestinal lymphocytes represent a reservoir for HAdV persistence and reactivation, whereas the intestinal epithelium is the main site of viral proliferation preceding dissemination. The findings have important implications for assessing the risk of life-threatening invasive HAdV infections.

Adenovirus infection and disease in paediatric haematopoietic stem cell transplant patients: clues for antiviral pre-emptive treatment

Human adenovirus (HAdV) infections constitute a major cause of morbidity in paediatric haematopoietic stem cell transplant (HSCT) patients. New antiviral treatments offer promising perspectives. However, it remains challenging to identify patients at risk for disseminated infection, and who should receive early antiviral intervention. We conducted a longitudinal study of allogeneic HSCT recipients, including weekly HAdV monitoring, to determine the risks factors associated with HAdV infection and dissemination, and to assess whether HAdV loads in stools may be used as surrogate markers for HAdV dissemination. Between September 2010 and December 2011, out of 72 patients, the cumulative incidence rates at day 100 of HAdV digestive infection, systemic infection and related disease were 35.9%, 24.0%, and 18.3%, respectively. In multivariate analysis, the risk factors for HAdV digestive and systemic infection were cord blood and in vitro T-cell depletion. Graft-versus-host disease (GVHD) grade >2 was also associated with systemic infection. In patients with HAdV digestive shedding, GVHD grade >2 and HAdV load in stools were the only risk factors for systemic infection. The median peak levels of HAdV in stool were 7.9 and 4.0 log10 copies/mL, respectively, in patients with HAdV systemic infection and in those without. HAdV monitoring in stools of paediatric HSCT recipients receiving cord blood or in vitro T-cell depleted transplants helps to predict patients at risk for HAdV systemic infection. Our results provide a rationale for randomized controlled trials to evaluate the benefit of anti-HAdV pre-emptive treatments based on HAdV DNA levels in stools.

Adenovirus infections in immunocompetent and immunocompromised patients

Human adenoviruses (HAdVs) are an important cause of infections in both immunocompetent and immunocompromised individuals, and they continue to provide clinical challenges pertaining to diagnostics and treatment. The growing number of HAdV types identified by genomic analysis, as well as the improved understanding of the sites of viral persistence and reactivation, requires continuous adaptions of diagnostic approaches to facilitate timely detection and monitoring of HAdV infections. In view of the clinical relevance of life-threatening HAdV diseases in the immunocompromised setting, there is an urgent need for highly effective treatment modalities lacking major side effects. The present review summarizes the recent progress in the understanding and management of HAdV infections.

Identification of a novel intertypic recombinant species D human adenovirus in a pediatric stem cell transplant recipient

BACKGROUND

Human adenoviruses (HAdV) are known opportunistic pathogens in hematopoietic stem cell transplant (SCT) recipients. The detection of HAdV infection in children after SCT has been implicated as a determinant of poor outcome but specific associations between HAdV species or individual HAdV types and disease are poorly understood.

OBJECTIVES

Characterization of a HAdV-D strain isolated from multiple clinical specimens of an 11-year-old female recipient of a matched unrelated donor peripheral SCT for T-cell lymphoma and case report.

STUDY DESIGN

Archived HAdV PCR-positive plasma, urine, and stool specimens were processed for virus isolation and detailed molecular typing. Complete genomic sequencing was carried out on 2 isolates.

RESULTS

The patient tested positive for HAdV DNA by real-time PCR of a stool specimen at 44 days after initiation of a SCT conditioning regimen. In the subsequent 3 months, HAdV was detected in plasma, urine and stool specimens in association with symptoms of gastroenteritis and hemorrhagic cystitis. A novel HAdV-D with a HAdV20-like hexon gene was isolated from both urine and stool specimens. All isolates yielded identical restriction profiles with endonucleases BamHI, BglII, BstEII, HindIII, PstI and SmaI. Analysis of 2 complete genomic sequences further identified the virus as a novel intertypic recombinant HAdV-D (P20/H20/F42) closely related to HAdV42.

CONCLUSIONS

This case highlights the identification of a previously unknown HAdV-D from an immunocompromised host. In this patient, the course of adenovirus infection is compatible with reactivation of a latent virus or a primary opportunistic infection. Adenoviremia in this patient resolved without definitive adenovirus-directed antiviral therapy.

Diagnosis and treatment of adenovirus infection in immunocompromised patients

In immunocompromised patients, human adenovirus (HAdV) infections can cause life-threatening multiorgan disease. This review summarizes the incidence and risk factors of invasive human adenovirus infections in immunocompromised patients as well as the recently developed standards for diagnostic methods and strategies according to the predominant risk factors in adults and children. Recommendations for preemptive and therapeutic treatment strategies and the outcome in different risk groups are presented. Novel therapeutic approaches including CMX001, a new orally bioavailable lipid conjugate of cidofovir and the transfer of adenovirus-specific donor T cells in the context of allogeneic stem cell transplantation are discussed.

Type dependent patterns of human adenovirus persistence in human T-lymphocyte cell lines

Disseminated adenovirus infections cause significant mortality in stem cell transplanted patients and are suspected to originate from asymptomatic adenovirus persistence ("latency") in lymphocytes. The infection of three human T-lymphocyte lines (Jurkat, PM1, and CEM) with human adenovirus types of species A (HAdV-A31), B (HAdV-B3, -B11), and C (HAdV-C2, -C5) was investigated for 150 days in order to establish in vitro models for adenovirus persistence. HAdV-C5 persisted with continuous production of infectious virus progeny (about 10(7) TCID50 /ml) in PM1 cells. More than 100 copies of HAdV-C5-DNA per cell were detected by real-time PCR but hexon immunostaining showed that only 7.5% of the cells were infected ("carrier state infection"). Coxsackie and adenovirus receptor (CAR) expression was decreased in comparison to mock infected cultures suggesting selection of a semi-permissive subpopulation of PM-1 cells. By contrast, latency of HAdV-DNA (10(-3) -10(-4)  copies/cell) without production of infectious virus progeny was observed in HAdV-C2 infection of PM1 and Jurkat, HAdV-A31 infection of PM1, and HAdV-B3 infection of Jurkat cells. In addition, transcription of E1A, DNA polymerase and hexon mRNA was not detected by RT-PCR suggesting an equivalent of clinical "HAdV latency." Persistence of HAdV-DNA was not observed in abortive infections of PM1 cells with HAdV-B3 and -B11 and in productive, lytical infections of Jurkat cells with HAdV-C5, HAdV-B11, and HAdV-A31. In conclusion, lytic and persistent infections with and without production of infectious virus were observed depending on the type of adenovirus. Genetic determinants for viral persistence may be investigated using these newly established infection models.

Chapter eight--Oncolytic adenoviruses for cancer immunotherapy: data from mice, hamsters, and humans

Adenovirus is one of the most commonly used vectors for gene therapy and two products have already been approved for treatment of cancer in China (Gendicine(R) and Oncorine(R)). An intriguing aspect of oncolytic adenoviruses is that by their very nature they potently stimulate multiple arms of the immune system. Thus, combined tumor killing via oncolysis and inherent immunostimulatory properties in fact make these viruses in situ tumor vaccines. When further engineered to express cytokines, chemokines, tumor-associated antigens, or other immunomodulatory elements, they have been shown in various preclinical models to induce antigen-specific effector and memory responses, resulting both in full therapeutic cures and even induction of life-long tumor immunity. Here, we review the state of the art of oncolytic adenovirus, in the context of their capability to stimulate innate and adaptive arms of the immune system and finally how we can modify these viruses to direct the immune response toward cancer.

Community acquired respiratory and gastrointestinal viral infections: challenges in the immunocompromised host

PURPOSE OF REVIEW

Newer molecular diagnostic techniques have advanced the field of clinical microbiology and infectious diseases, particularly with respect to characterizing the role that community acquired viruses play in the clinical course and outcomes of the immunocompromised host. This review will examine recent studies describing the impact of adenovirus, rhinovirus, hepatitis E and norovirus in the course of solid organ and stem cell transplant recipients, as well as their epidemiology and implications for infection prevention and control.

RECENT FINDINGS

Adenovirus transmission is poorly understood; recent studies increasingly point to reactivation of latent infection in the immunocompromised host. Rhinovirus shedding can persist for weeks after acute viral infection, complicating hospital infection control policies. Hepatitis E is increasingly recognized as a potential pathogen in the stem cell and solid organ transplant population, and should be considered in the work-up for unexplained liver function test abnormalities. Similar to rhinovirus, norovirus shedding from the gastrointestinal tract may persist for months in the immunocompromised host; infected patients are at a higher risk for transmitting norovirus compared with infected healthcare workers.

SUMMARY

Additional studies are needed, particularly with respect to transmission, for these community acquired viral infections, which often have devastating consequences in the immunocompromised patient population.

Epidemiology and potential preventative measures for viral infections in children with malignancy and those undergoing hematopoietic cell transplantation

In pediatric patients with malignancy and those receiving hematopoietic stem cell transplants, bacterial and fungal infections have been the focus of fever and neutropenia episodes for decades. However, improved diagnostic capabilities have revealed viral pathogens as a significant cause of morbidity and mortality. Because of limited effective antiviral therapies, prevention of viral infections is paramount. Pre-exposure and post-exposure prophylaxis and antiviral suppressive therapeutic approaches are reviewed. Additionally, infection control practices specific to this patient population are discussed. A comprehensive approach utilizing each of these can be effective at reducing the negative impact of viral infections.

Incidence and treatment strategy for disseminated adenovirus disease after haploidentical stem cell transplantation

Adenovirus (AdV) infection is an emerging complication in patients undergoing allogeneic stem cell transplantation (SCT) and is closely associated with delayed immune reconstitution. In particular, disseminated AdV disease accompanies a high mortality. We retrospectively examined the incidence of AdV infection in patients undergoing unmanipulated haploidentical SCT. Following 121 transplantations in 110 patients, three had asymptomatic AdV viremia, three had localized AdV disease (hemorrhagic cystitis, HC), and seven had disseminated AdV disease (HC + viremia). The median time from transplantation to the onset of AdV-associated HC was 15 days (range 4-39), and the median time to the onset of disseminated AdV disease was 23 days (range 7-38). The cumulative incidence of AdV-associated HC was 8.3 %, and that of disseminated AdV disease was 5.8 %. AdV group B (type 11, type 34, or type 35) was detected in plasma samples from all the patients with disseminated AdV disease. Among them, three patients who received either cidofovir or donor lymphocyte infusion (DLI) alone progressed to pneumonia and died. The remaining four patients were treated with the combination of cidofovir and low-dose unmanipulated DLI, and all survived. We showed that disseminated AdV disease is a significant complication after haplo-SCT and that the combination of cidofovir and DLI is a promising treatment option.