Adenovirus infections in immunocompetent and immunocompromised patients

Novel adenoviruses detected in British mustelids, including a unique Aviadenovirus in the tissues of pine martens (Martes martes)

Several adenoviruses are known to cause severe disease in veterinary species. Recent evidence suggests that canine adenovirus type 1 (CAV-1) persists in the tissues of healthy red foxes (Vulpes vulpes), which may be a source of infection for susceptible species. It was hypothesized that mustelids native to the UK, including pine martens (Martes martes) and Eurasian otters (Lutra lutra), may also be persistently infected with adenoviruses. Based on high-throughput sequencing and additional Sanger sequencing, a novel Aviadenovirus, tentatively named marten adenovirus type 1 (MAdV-1), was detected in pine marten tissues. The detection of an Aviadenovirus in mammalian tissue has not been reported previously. Two mastadenoviruses, tentatively designated marten adenovirus type 2 (MAdV-2) and lutrine adenovirus type 1 (LAdV-1), were also detected in tissues of pine martens and Eurasian otters, respectively. Apparently healthy free-ranging animals may be infected with uncharacterized adenoviruses with possible implications for translocation of wildlife.

MicroRNAs as Important Players in Host-Adenovirus Interactions

MicroRNAs (miRNAs) are powerful regulators of gene expression and fine-tuning genes in all tissues. Cellular miRNAs can control 100s of biologic processes (e.g., morphogenesis of embryonic structures, differentiation of tissue-specific cells, and metabolic control in specific cell types) and have been involved in the regulation of nearly all cellular pathways. Inherently to their involvement in different physiologic processes, miRNAs deregulation has been associated with several diseases. Moreover, several viruses have been described as either, avoid and block cellular miRNAs or synthesize their own miRNA to facilitate infection and pathogenesis. Adenoviruses genome encodes two non-coding RNAs, known as viral-associated (VA) RNA_I and VA RNA_II, which seem to play an important role either by blocking important proteins from miRNA pathway, such as Exportin-5 and Dicer, or by targeting relevant cellular factors. Drastic changes in cellular miRNA expression profile are also noticeable and several cellular functions are affected by these changes. This review focuses on the mechanisms underlying the biogenesis and molecular interactions of miRNAs providing basic concepts of their functions as well as in the interplay between miRNAs and human adenoviruses.

Anti-adenoviral Artificial MicroRNAs Expressed from AAV9 Vectors Inhibit Human Adenovirus Infection in Immunosuppressed Syrian Hamsters

Infections of immunocompromised patients with human adenoviruses (hAd) can develop into life-threatening conditions, whereas drugs with anti-adenoviral efficiency are not clinically approved and have limited efficacy. Small double-stranded RNAs that induce RNAi represent a new class of promising anti-adenoviral therapeutics. However, as yet, their efficiency to treat hAd5 infections has only been investigated in vitro. In this study, we analyzed artificial microRNAs (amiRs) delivered by self-complementary adeno-associated virus (scAAV) vectors for treatment of hAd5 infections in immunosuppressed Syrian hamsters. In vitro evaluation of amiRs targeting the E1A, pTP, IVa2, and hexon genes of hAd5 revealed that two scAAV vectors containing three copies of amiR-pTP and three copies of amiR-E1A, or six copies of amiR-pTP, efficiently inhibited hAd5 replication and improved the viability of hAd5-infected cells. Prophylactic application of amiR-pTP/amiR-E1A- and amiR-pTP-expressing scAAV9 vectors, respectively, to immunosuppressed Syrian hamsters resulted in the reduction of hAd5 levels in the liver of up to two orders of magnitude and in reduction of liver damage. Concomitant application of the vectors also resulted in a decrease of hepatic hAd5 infection. No side effects were observed. These data demonstrate anti-adenoviral RNAi as a promising new approach to combat hAd5 infection.

Limited diagnostic value of a multiplexed gastrointestinal pathogen panel for the detection of adenovirus infection in an oncology patient population

BACKGROUND

Diagnosis of Adenovirus infections in transplant patients may be accomplished using either plasma or stool samples. IVD-cleared multiplexed gastrointestinal (GI) PCR panels offer an option for rapid testing of stool samples but most only target Adenovirus (HAdV) types F40/41.

OBJECTIVES

Given the potential significance of a positive adenovirus test in an immunocompromised patient, we sought to determine the frequency of type 40/41 in our patient population and the utility of a readily available multiplexed, FDA-cleared GI Panel for the detection of adenovirus infections.

STUDY DESIGN

A total of 215 specimens from immunocompromised patients mostly with hematologic malignancy or transplant recipients were evaluated including 107 plasma samples, 85 stool samples and 23 respiratory samples. Genotyping was performed successfully on 122 specimens.

RESULTS

The most common type detected in all samples including stools was Adenovirus C/2. In a subset of patients with multiple specimen types tested, similar types were detected in all samples.

CONCLUSIONS

Although Adenovirus F40/41 is the most common enteric type, Adenovirus C/2 was the most common type identified in stools and subsequently plasma samples of our patient population. Implementation of assays that have wide reactivity for most adenovirus types is essential for optimal diagnostic yield.

Adenovirus

Adenoviruses are a highly prevalent infection that can cause a range of clinical syndromes in immunocompromised patients, ranging from localized disease of the respiratory tract, gastrointestinal tract, or urinary tract to disseminated disease. Adenovirus infections may develop in this unique population as the result of primary infection or reactivation of latent virus. Disease can be potentially progressive with high rates of mortality in patients with pneumonia and disseminated disease. Fortunately, cidofovir and its lipid ester, brincidofovir, appear to be effective for the treatment of adenovirus, although neither is specifically approved for this indication. Adenovirus should always be considered when immunocompromised patients present with any clinical syndrome that could be compatible with adenoviral infection. Once disease is suspected, cultures or molecular testing of appropriate specimens should be obtained and blood should be sent for adenovirus polymerase chain reaction (PCR) whenever adenovirus is suspected. Monitoring of quantitative viral loads in blood is helpful in predicting response to therapy with a significant drop (>1 log) associated with a higher probability of clinical response.

The nuclear export factor CRM1 controls juxta-nuclear microtubule-dependent virus transport

Transport of large cargo through the cytoplasm requires motor proteins and polarized filaments. Viruses that replicate in the nucleus of post-mitotic cells use microtubules and the dynein-dynactin motor to traffic to the nuclear membrane and deliver their genome through nuclear pore complexes (NPCs) into the nucleus. How virus particles (virions) or cellular cargo are transferred from microtubules to the NPC is unknown. Here, we analyzed trafficking of incoming cytoplasmic adenoviruses by single-particle tracking and super-resolution microscopy. We provide evidence for a regulatory role of CRM1 (chromosome-region-maintenance-1; also known as XPO1, exportin-1) in juxta-nuclear microtubule-dependent adenovirus transport. Leptomycin B (LMB) abolishes nuclear targeting of adenovirus. It binds to CRM1, precludes CRM1-cargo binding and blocks signal-dependent nuclear export. LMB-inhibited CRM1 did not compete with adenovirus for binding to the nucleoporin Nup214 at the NPC. Instead, CRM1 inhibition selectively enhanced virion association with microtubules, and boosted virion motions on microtubules less than ∼2 µm from the nuclear membrane. The data show that the nucleus provides positional information for incoming virions to detach from microtubules, engage a slower microtubule-independent motility to the NPC and enhance infection.

Hospital-Associated Infections

Hospital-associated infection (HAI) in immunocompromised patients can result in high rates of morbidity and mortality. Infections caused by multidrug-resistant organisms (MDROs) are especially worrisome because of the limited choice of remaining antibiotics available when a patient becomes colonized or infected with an MDRO. It is therefore important that immunocompromised patients be cared for in an environment that limits the risk for acquiring infections. However, with healthcare being increasingly delivered in settings other than the traditional inpatient hospital wards, a bigger effort will need to be set forth to prevent or rapidly diagnose HAI. The last few years have seen a significant increase in the number of singleplex and multiplex molecular assays for the detection of many of the organisms responsible for HAI, but more is needed as infections caused by organisms like Legionella pneumophila and Aspergillus species are still diagnosed with methods that have relatively low yield and are slow to provide actionable results. Finally, the use of novel techniques for outbreak investigations will provide new information on transmission of infectious agents in healthcare settings and allow stronger, evidence-based recommendations to be developed for prevention of HAIs in the immunocompromised host.

Development of a prototype immunochromatographic test for rapid diagnosis of respiratory adenovirus infection

Human adenoviruses comprise an important group of etiologic agents that are responsible for various diseases in adults and children, such as respiratory, ocular, gastroenteric, and urinary infections. In immunocompromised and organ-transplanted individuals, these agents can cause generalized infections. Rapid diagnostic methods for detecting these infectious agents are not widely available.

The aim of this work was to produce monoclonal and polyclonal anti-adenovirus antibodies to be used in a rapid diagnostic test for respiratory infections.

Adenovirus hexons were satisfactorily purified by ultracentrifugation and chromatography. After virus purification, anti-hexon monoclonal antibodies were produced and characterized, following classical methods. Antibodies were specific for adenoviruses 2, 3, 5, and 41. The proposed immunochromatographic test was standardized using colloidal gold.

The standardization of the rapid test was sufficient to detect adenovirus antigens (in nasopharyngeal lavage samples) with sensitivity of 100% and specificity of 85% when compared to direct immunofluorescence.

The immunochromatographic assay prototype was sufficiently sensitive to detect B (3), C (2 and 5), and F (41) adenovirus samples. Although based on preliminary data, the test demonstrated the same performance as direct immunofluorescence, but with the advantage of being a point-of-care test. Further studies are still needed to confirm its effectiveness in clinical practice.

HAdV-C6 Is a More Relevant Challenge Virus than HAdV-C5 for Testing Antiviral Drugs with the Immunosuppressed Syrian Hamster Model

Adenovirus infections of immunocompromised patients can cause a severe multi-organ disease that often results in the patients' death. Presently, there are no drugs specifically approved to treat adenovirus infections, and clinicians resort to the off-label use of antivirals that are approved to treat other DNA virus infections, most frequently cidofovir (CDV). CDV, however, has considerable nephrotoxicity, thus it is recommended only for the most severe cases of adenovirus infections. To facilitate the development of effective, non-toxic antivirals against adenovirus, we have developed a permissive animal model based on the Syrian hamster that can be used to test the efficacy of antiviral compounds. Here, we show that in the hamster model, HAdV-C6 is a more useful challenge virus than the previously described HAdV-C5, because it is filtered out by tissue macrophages to a lesser extent. HAdV-C6 has a 10-fold lower LD50 in hamsters than HAdV-C5 and the pathology is caused by virus replication to a larger extent. We show that valganciclovir (VGCV), a drug that was shown to be active against intravenous HAdV-C5 infection previously, is efficacious against HAdV-C6 when administered either prophylactically or therapeutically. Further, we show for the first time that VGCV, and to a lesser extent CDV, can be used to treat respiratory adenovirus infections in the hamster model. These results extend the utility of the hamster model, and demonstrate the efficacy of two drugs available for clinicians to treat adenovirus infections.

Cell Cycle-Dependent Kinase Cdk9 Is a Postexposure Drug Target against Human Adenoviruses

Human adenoviruses (HAdVs) infect respiratory, gastrointestinal, and urinary tracts and give rise to eye infections and epidemic keratoconjunctivitis (EKC). They persist in lymphoid tissue and cause morbidity and mortality in immunocompromised people. Treatments with significant postexposure efficacy are not available. Here, we report that inhibition of the cell cycle-dependent kinase 9 (Cdk9) by RNA interference, or the compound flavopiridol, blocked infections with HAdV-C2/5, EKC-causing HAdV-D8/37, and progeny formation in human corneal epithelial and cancer cells. Flavopiridol abrogated the production of the immediate early viral transactivating protein E1A without affecting nuclear import of viral DNA. In morphometric plaque assays, the compound exhibited antiviral efficacy in both pre- and postexposure regimens with therapeutic indexes exceeding 10. The study identifies Cdk9 as a postexposure drug target against adenovirus infections in vitro and suggests that the clinically tested anticancer drug flavopiridol is a candidate for treating adenoviral EKC or adenovirus emergence upon immune suppression.

How to: Establish and run a stool bank

BACKGROUND

Since 2013, several stool banks have been developed following publications reporting on clinical success of 'faecal microbiota transplantation' (FMT) for recurrent Clostridium difficile infections (CDI). However, protocols for donor screening, faecal suspension preparation, and transfer of the faecal suspension differ between countries and institutions. Moreover, no European consensus exists regarding the legislative aspects of the faecal suspension product. Internationally standardized recommendations about the above mentioned aspects have not yet been established.

OBJECTIVE

In 2015, the Netherlands Donor Feces Bank (NDFB) was founded with the primary aim of providing a standardized product for the treatment of patients with recurrent CDI in the Netherlands. Standard operation procedures for donor recruitment, donor selection, donor screening, and production, storage, and distribution of frozen faecal suspensions for FMT were formulated.

RESULTS AND DISCUSSION

Our experience summarized in this review addresses current donor recruitment and screening, preparation of the faecal suspension, transfer of the faecal microbiota suspension, and the experiences and follow-up of the patients treated with donor faeces from the NDFB.

Simultaneous Single-Cell In Situ Analysis of Human Adenovirus Type 5 DNA and mRNA Expression Patterns in Lytic and Persistent Infection

An efficient adenovirus infection results in high-level accumulation of viral DNA and mRNAs in the infected cell population. However, the average viral DNA and mRNA content in a heterogeneous cell population does not necessarily reflect the same abundance in individual cells. Here, we describe a novel padlock probe-based rolling-circle amplification technique that enables simultaneous detection and analysis of human adenovirus type 5 (HAdV-5) genomic DNA and virus-encoded mRNAs in individual infected cells. We demonstrate that the method is applicable for detection and quantification of HAdV-5 DNA and mRNAs in short-term infections in human epithelial cells and in long-term infections in human B lymphocytes. Single-cell evaluation of these infections revealed high heterogeneity and unique cell subpopulations defined by differential viral DNA content and mRNA expression. Further, our single-cell analysis shows that the specific expression pattern of viral E1A 13S and 12S mRNA splice variants is linked to HAdV-5 DNA content in the individual cells. Furthermore, we show that expression of a mature form of the HAdV-5 histone-like protein VII affects virus genome detection in HAdV-5-infected cells. Collectively, padlock probes combined with rolling-circle amplification should be a welcome addition to the method repertoire for the characterization of the molecular details of the HAdV life cycle in individual infected cells.IMPORTANCE Human adenoviruses (HAdVs) have been extensively used as model systems to study various aspects of eukaryotic gene expression and genome organization. The vast majority of the HAdV studies are based on standard experimental procedures carried out using heterogeneous cell populations, where data averaging often masks biological differences. As every cell is unique, characteristics and efficiency of an HAdV infection can vary from cell to cell. Therefore, the analysis of HAdV gene expression and genome organization would benefit from a method that permits analysis of individual infected cells in the heterogeneous cell population. Here, we show that the padlock probe-based rolling-circle amplification method can be used to study concurrent viral DNA accumulation and mRNA expression patterns in individual HAdV-5-infected cells. Hence, this versatile method can be applied to detect the extent of infection and virus gene expression changes in different HAdV-5 infections.

Respiratory viruses in patients with influenza-like illness in Senegal: Focus on human respiratory adenoviruses

Background

Human adenoviruses (HAdVs) are highly contagious pathogens that are associated with a wide spectrum of human illnesses involving the respiratory tract. In the present study, we investigate the epidemiologic and viral molecular features of HAdVs circulating in Senegal after 4 consecutive years of sentinel surveillance of influenza-like Illness cases.

Methodology and results

From January 2012 to December 2015 swabs were collected from consenting ILI outpatients. Adenoviral detection is performed by rRT-PCR with the Anyplex^™ II RV16 Detection kit (Seegene) and molecular characterization was performed using a partial hexon gene sequence. 6381 samples were collected. More than half of patients (51.7%; 3297/6381) were children of ≤ 5 years. 1967 (30.8%) were positive for HAdV with 1561 (79.4%) found in co-infection with at least one another respiratory virus. The most common co-detections were with influenza viruses (53.1%; 1045/1967), rhinoviruses (30%; 591/1967), enteroviruses (18.5%; 364/1967) and RSV (13.5%; 266/1967). Children under 5 were the most infected group (62.2%; 1224/1967; p <0.05). We noted that HAdV was detected throughout the year at a high level with detection peaks of different amplitudes without any clear seasonality. Phylogenetic analysis revealed species HAdV-C in majority, species HAdV-B and one HAdV- 4 genome type. The 9 HAdV-B species like strains from Senegal grouped with genome types HAdV-7, HAdV-55 and HAdV-11 as shown by a phylogenetic branch with a high bootstrap value of (88%).

Conclusion

In conclusion, the results of the present study suggest strong year-round HAdV activity in Senegal, especially in children up to 5 years of age. Molecular studies revealed that the dominant species in circulation in patients with ILI appears to be HAdV-C and HAdV-B species. The circulation of though HAdV-7 and HAdV-55 genome types is of note as these serotypes are recognized causes of more severe and even fatal acute respiratory infections.

One-year Surveillance of Human Enteric Viruses in Raw and Treated Wastewaters, Downstream River Waters, and Drinking Waters

Human enteric viruses are a major cause of waterborne diseases, and can be transmitted by contaminated water of all kinds, including drinking and recreational water. The objectives of the present study were to assess the occurrence of enteric viruses (enterovirus, norovirus, adenovirus, hepatitis A and E virus) in raw and treated wastewaters, in rivers receiving wastewater discharges, and in drinking waters. Wastewater treatment plants' (WWTP) pathogen removal efficiencies by adenovirus quantitative real-time PCR and the presence of infectious enterovirus, by cell culture assays, in treated wastewaters and in surface waters were also evaluated. A total of 90 water samples were collected: raw and treated wastewaters (treated effluents and ultrafiltered water reused for industrial purposes), water from two rivers receiving treated discharges, and drinking water. Nested PCR assays were used for the identification of viral DNA/RNA, followed by direct amplicon sequencing. All raw sewage samples (21/21), 61.9 % of treated wastewater samples (13/21), and 25 % of ultrafiltered water samples (3/12) were contaminated with at least one viral family. Multiple virus families and genera were frequently detected. Mean positive PCRs per sample decreased significantly from raw to treated sewage and to ultrafiltered waters. Moreover, quantitative adenovirus data showed a reduction in excess of 99 % in viral genome copies following wastewater treatment. In surface waters, 78.6 % (22/28) of samples tested positive for one or more viruses by molecular methods, but enterovirus-specific infectivity assays did not reveal infectious particles in these samples. All drinking water samples tested negative for all viruses, demonstrating the effectiveness of treatment in removing viral pathogens from drinking water. Integrated strategies to manage water from all sources are crucial to ensure water quality.

Clinical Features and Courses of Adenovirus Pneumonia in Healthy Young Adults during an Outbreak among Korean Military Personnel

Background

The number of pneumonia patients increased suddenly in Korean military hospitals in late December 2014, indicating the urgent need for an epidemic outbreak investigation.

Methods

We conducted a prospective study of pneumonia etiology among immunocompetent young adults admitted to Daejeon Armed Forces hospital. Patient blood and sputum samples were subjected to conventional culture, serology, and polymerase chain reaction tests for respiratory viruses and atypical pathogens.

Results

From January to May 2015, we enrolled 191 (189 male) adults with pneumonia; the mean age was 20.1 ± 1.3 years. Five patients had severe pneumonia, and one died. Pathogenic human adenoviruses were most common (HAdV, 153/191 [80.1%]), indicating a HAdV pneumonia outbreak. Genotyping of 35 isolates indicated that 34 matched HAdV-55 and one matched HAdV-2. HAdV pneumonia infected recruit trainees most frequently. High and prolonged fever, nasal congestion, sore throat, and pharyngeal inflammation were significantly more common in the HAdV pneumonia group, compared to patients with other or unknown causes of pneumonia. Only 12% of HAdV pneumonia patients displayed leukocytosis, whereas febrile leukopenia (62.7%) and thrombocytopenia (41%) were commonly observed. HAdV pneumonia patient chest CT scans displayed ground glass opacity (with or without septal thickness) with consolidation in 50.0% of patients.

Conclusions

An outbreak of HAdV respiratory infection occurred at the Korean military training center. HAdV pneumonia exhibited specific laboratory and clinical features, and although most patients were cured without complication, some progressed to respiratory failure and fatality. Therefore, HAdV vaccine should be provided to military trainees in Korea.

Suppression of Adenovirus Replication by Cardiotonic Steroids

The dependence of adenovirus on the host pre-RNA splicing machinery for expression of its complete genome potentially makes it vulnerable to modulators of RNA splicing, such as digoxin and digitoxin. Both drugs reduced the yields of four human adenoviruses (HAdV-A31, -B35, and -C5 and a species D conjunctivitis isolate) by at least 2 to 3 logs by affecting one or more steps needed for genome replication. Immediate early E1A protein levels are unaffected by the drugs, but synthesis of the delayed protein E4orf6 and the major late capsid protein hexon is compromised. Quantitative reverse transcription-PCR (qRT-PCR) analyses revealed that both drugs altered E1A RNA splicing (favoring the production of 13S over 12S RNA) early in infection and partially blocked the transition from 12S and 13S to 9S RNA at late stages of virus replication. Expression of multiple late viral protein mRNAs was lost in the presence of either drug, consistent with the observed block in viral DNA replication. The antiviral effect was dependent on the continued presence of the drug and was rapidly reversible. RIDK34, a derivative of convallotoxin, although having more potent antiviral activity, did not show an improved selectivity index. All three drugs reduced metabolic activity to some degree without evidence of cell death. By blocking adenovirus replication at one or more steps beyond the onset of E1A expression and prior to genome replication, digoxin and digitoxin show potential as antiviral agents for treatment of serious adenovirus infections. Furthermore, understanding the mechanism(s) by which digoxin and digitoxin inhibit adenovirus replication will guide the development of novel antiviral therapies.

IMPORTANCE

Despite human adenoviruses being a common and, in some instances, life-threating pathogen in humans, there are few well-tolerated therapies. In this report, we demonstrate that two cardiotonic steroids already in use in humans, digoxin and digitoxin, are potent inhibitors of multiple adenovirus species. A synthetic derivative of the cardiotonic steroid convallotoxin was even more potent than digoxin and digitoxin when tested with HAdV-C5. These drugs alter the cascade of adenovirus gene expression, acting after initiation of early gene expression to block viral DNA replication and synthesis of viral structural proteins. These findings validate a novel approach to treating adenovirus infections through the modulation of host cell processes.

Presentation of a Conserved Adenoviral Epitope on HLA-C*0702 Allows Evasion of Natural Killer but Not T Cell Responses

Infection with adenovirus is a major cause of infectious mortality in children following hematopoietic stem-cell transplantation. While adoptive transfer of epitope-specific T cells is a particularly effective therapeutic approach, there are few suitable adenoviral peptide epitopes described to date. Here, we describe the adenoviral peptide epitope FRKDVNMVL from hexon protein, and its variant FRKDVNMIL, that is restricted by human leukocyte antigen (HLA)-C*0702. Since HLA-C*0702 can be recognized by both T cells and natural killer (NK) cells, we characterized responses by both cell types. T cells specific for FRKDVNMVL were detected in peripheral blood mononuclear cells expanded from eight of ten healthy HLA-typed donors by peptide-HLA multimer staining, and could also be detected by cultured interferon γ ELISpot assays. Surprisingly, HLA-C*0702 was not downregulated during infection, in contrast to the marked downregulation of HLA-A*0201, suggesting that adenovirus cannot evade T cell responses to HLA-C*0702-restricted peptide epitopes. By contrast, NK responses were inhibited following adenoviral peptide presentation. Notably, presentation of the FRKDVNMVL peptide enhanced binding of HLA-C*0702 to the inhibitory receptor KIR2DL3 and decreased NK cytotoxic responses, suggesting that adenoviruses may use this peptide to evade NK responses. Given the immunodominance of FRKDVNMVL-specific T cell responses, apparent lack of HLA-C*0702 downregulation during infection, and the high frequency of this allotype, this peptide epitope may be particularly useful for adoptive T cell transfer therapy of adenovirus infection.

Clinical characteristics and outcomes of adenovirus infection of the urinary tract after renal transplantation

BACKGROUND

Urinary tract infection caused by human adenovirus (HAdV) after renal transplantation (RT) results in graft loss because of concomitant nephropathy and acute rejection and may result in death because of systemic dissemination.

METHODS

We assessed the time period between RT and disease onset, symptoms, treatment details, disease duration, renal graft function, outcomes, and complications.

RESULTS

HAdV infection of the urinary tract occurred in 8 of 170 renal transplant recipients. Symptoms were macrohematuria in all 8 patients, dysuria in 7, and fever in 5. The median period from RT to disease onset was 367 (range, 7-1763) days, and the median disease duration was 15 (range, 8-42) days. The mean serum creatinine (sCr) level prior to onset was 1.35 ± 0.48 mg/dL and the mean maximum sCr level during disease was 2.34 ± 1.95 mg/dL. These values were increased by ≥25% in 5 patients. The mean sCr levels when symptoms resolved was 1.54 ± 0.67 mg/dL, and no significant difference was seen before, during, or after disease onset (P = 0.069). Two patients were diagnosed with HAdV viremia and 1 with acute tubulointerstitial nephritis revealed on biopsy. In addition to a reduction in immunosuppressant dosage, 2 patients received gammaglobulins and 5 received ganciclovir.

CONCLUSION

Symptoms of all patients were alleviated, although some patients developed nephritis or viremia. Hence, the possibility of exacerbation should always be considered. Adequate follow-up observation should be conducted, and diligent and aggressive therapeutic intervention is required to prevent the condition from worsening.

Brincidofovir for Asymptomatic Adenovirus Viremia in Pediatric and Adult Allogeneic Hematopoietic Cell Transplant Recipients: A Randomized Placebo-Controlled Phase II Trial

Adenovirus infection in immunocompromised patients contributes to significant morbidity and mortality, especially after allogeneic hematopoietic cell transplantation (HCT). Brincidofovir (BCV, CMX001) is an orally bioavailable lipid conjugate of cidofovir that has in vitro activity against adenoviruses and other double-stranded DNA viruses. This randomized placebo-controlled phase II trial evaluated pre-emptive treatment with BCV for the prevention of adenovirus disease in pediatric and adult allogeneic HCT recipients with asymptomatic adenovirus viremia. Allogeneic HCT recipients with adenovirus viremia were randomized 1:1:1 to receive oral BCV 100 mg (2 mg/kg if <50 kg) twice weekly (BIW), BCV 200 mg (4 mg/kg if <50 kg) once weekly (QW), or placebo for 6 to 12 weeks, followed by 4 weeks of post-treatment follow-up. For randomization, subjects were stratified by screening absolute lymphocyte count (<300 cells/mm³ versus ≥300 cells/mm³). Assignment to BCV or placebo was double blinded; dose frequency was unblinded. The primary endpoint was the proportion of subjects experiencing treatment failure, defined as either progression to probable or definitive adenovirus disease or confirmed increasing adenovirus viremia (≥1 log₁₀ copies/mL) during randomized therapy. Between June 2011 and December 2012, 48 subjects were randomized to the BCV BIW (n = 14), BCV QW (n = 16), or placebo (n = 18) groups. The proportion of subjects with treatment failure in the BCV BIW group was 21% (odds ratio, .53; 95% confidence interval [CI], .11 to 2.71; P = .45), 38% (odds ratio, 1.23; 95% CI, .30 to 5.05, P = .779) in the BCV QW group, and 33% in the placebo group. All-cause mortality was lower in the BCV BIW (14%) and BCV QW groups (31%) relative to the placebo group (39%), but these differences were not statistically significant. After 1 week of therapy, 8 of 12 subjects (67%) randomized to BCV BIW had undetectable adenovirus viremia (<100 copies/mL), compared with 4 of 14 subjects (29%) randomized to BCV QW and 5 of 15 subjects (33%) randomized to placebo. In a post hoc analysis of subjects with viremia ≥1000 copies/mL at baseline, 6 of 7 BCV BIW subjects (86%) achieved undetectable viremia compared with 2 of 8 placebo subjects (25%; P = .04). Early treatment discontinuation because of adverse events was more common in subjects treated with BCV than with placebo. Diarrhea was the most common event in all groups (57% BCV BIW, 38% BCV QW, 28% placebo), but it led to treatment discontinuation in only 1 subject receiving BCV QW. Events diagnosed as acute graft-versus-host disease, primarily of the gastrointestinal tract, were more frequent in the BCV BIW group (50%) than in the BCV QW (25%) and placebo (17%) groups. There was no evidence of myelotoxicity or nephrotoxicity in BCV-treated subjects. The results of this trial confirm the antiviral activity of BCV against adenoviruses. Further investigation is ongoing to define the optimal treatment strategy for HCT recipients with serious adenovirus infection and disease.

Fatal Community-acquired Pneumonia in Children Caused by Re-emergent Human Adenovirus 7d Associated with Higher Severity of Illness and Fatality Rate

Human adenoviruses (HAdVs) are highly contagious pathogens causing acute respiratory disease (ARD), such as community-acquired pneumonia. HAdV-7d, a re-emergent genomic variant, has been recently reported in Asia and the United States after a several-decade absence. However, whether HAdV-7d is associated with higher severity than other types is currently unclear. In this study, the clinical and epidemiological investigation showed that fever, cough, and sore throat were the three most common respiratory symptoms of HAdV infections. HAdV-7 caused longer duration of fever, higher morbidity of tachypnea/dyspnea, pleural effusion, diarrhea, hepatosplenomegaly, consciousness alteration, as well as higher rates of pneumonia, mechanical ventilation and higher fatality rate (28.6%) than other types, particularly HAdV-3 and HAdV-2. The genomes of seven HAdV-7d isolates from mild, severe, and fatal cases were sequenced and highly similar with each other. Surprisingly, two isolates (2011, 2012) had 100% identical genomes with an earlier strain from a fatal ARD outbreak in China (2009), which elucidates the virus origin and confirms the unexpected HAdV genomic conservation and stability. Phylogenetic analysis indicated that L1 52/55-kDa DNA packaging protein may be associated with the higher severity of illness and fatality rate of HAdV-7. Clinicians need to be aware of HAdVs in children with ARD.

Genome Sequence of a Cynomolgus Macaque Adenovirus (CynAdV-1) Isolate from a Primate Colony in the United Kingdom

The genome sequence of a simian adenovirus from a cynomolgus macaque, denoted CynAdV-1, is presented here. Phylogenetic analysis supports CynAdV-1 in an independent clade, comprising a new simian adenovirus (SAdV) species. These genome data are critical for understanding the evolution and relationships of primate adenoviruses, including zoonosis and emergent human pathogens.

The ubiquity of asymptomatic respiratory viral infections in the tonsils and adenoids of children and their impact on airway obstruction

BACKGROUND

Airway obstruction due to enlargement of tonsils and adenoids is a common pediatric problem resulting in sleep disordered breathing. The cause for the relatively abnormal growth of tonsils and adenoids is poorly understood.

METHODS

Non-acutely ill children undergoing tonsillectomy and adenoidectomy (T&A) for various reasons were enrolled prospectively in a study to determine the frequency of asymptomatic respiratory viral infections in each lymphoid tissue and to relate the number and types of virus to the degree of airway obstruction. Molecular techniques were used to detect 9 respiratory viruses while Brodsky scores and measurements of percentages airway obstruction were used to estimate the degree of airway compromise due to the tonsil and adenoid, respectively.

RESULTS

Viruses were detected in 70.9% of tonsils and 94.7% of adenoids, p < 0.001. Adenovirus was the most common virus detected at 71.1%. Adenoids had an average of 2.4 viruses compared to 0.92 for tonsils, p < 0.001. Higher Brodsky scores were only associated with EBV in tonsils, p = 0.03, while greater percentages of airway obstruction in the adenoids were associated with adenovirus, EBV, corona virus, parainfluenza virus and rhinovirus, p ≤ 0.005.

CONCLUSIONS

Asymptomatic viral infections are common and directly related to the degree of airway obstruction significantly more often in adenoids than tonsils.

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.

Discovery of immunodominant T-cell epitopes reveals penton protein as a second immunodominant target in human adenovirus infection

Background

Human adenovirus (HAdV) infections remain a significant cause of morbidity and mortality after hematopoietic stem cell transplantation (HSCT). Efficient antiviral T-cell responses are necessary to clear infection, which is hampered by delayed immune reconstitution and medical immunosuppression after HSCT. Protective immunity may be conferred by adoptive transfer of HAdV-specific T cells. For identification of patients at risk and monitoring of treatment responses diligent assessment of anti-HAdV cellular immune responses is crucial. The HAdV-derived protein hexon has been recognized as a major immunodominant target across HAdV species. We aimed at identifying further targets of protective anti-HAdV immune response and characterizing immunogenic epitopes.

Methods

Nineteen candidate nonamers from hexon and penton proteins were identified by epitope binding prediction. Peptides were synthesized and tested for in vivo immunogenicity by screening peripheral blood mononuclear cells from healthy volunteers (n = 64) and HAdV-infected stem cell recipients (n = 26) for memory T cells recognizing the candidate epitopes in the context of most common HLA alleles.

Results

Functional CD8⁺ T cells recognizing seven epitopes were identified, among them four penton-derived and two hexon-derived peptides. The HLA-A*01-restricted penton-derived peptide STDVASLNY (A01Penton_STDV) and HLA-A*02-restricted hexon-derived peptide TLLYVLFEV (A02Hexon_TLLY) were recognized by more than half of the persons carrying the respective HLA-type.

Conclusions

Thus, the HAdV-derived penton protein is a novel major target of the anti-HAdV immune response. Identification of new immunodominant epitopes will facilitate and broaden immune assessment strategies to identify patients suitable for T-cell transfer. Knowledge of additional target structures may increase T-cell recovery in manufacturing processes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-1042-2) contains supplementary material, which is available to authorized users.

Adenovirus Early Proteins and Host Sumoylation

The human adenovirus genome is transported into the nucleus, where viral gene transcription, viral DNA replication, and virion assembly take place. Posttranslational modifications by small ubiquitin-like modifiers (SUMOs) are implicated in the regulation of diverse cellular processes, particularly nuclear events. It is not surprising, therefore, that adenovirus modulates and utilizes the host sumoylation system. Adenovirus early proteins play an important role in establishing optimal host environments for virus replication within infected cells by stimulating the cell cycle and counteracting host antiviral defenses. Here, we review findings on the mechanisms and functional consequences of the interplay between human adenovirus early proteins and the host sumoylation system.

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.

Brincidofovir clearance of acyclovir-resistant herpes simplex virus-1 and adenovirus infection after stem cell transplantation

Infections with adenovirus (AdV) and herpesviruses can result in considerable morbidity and mortality in pediatric hematopoietic stem cell transplant (SCT) recipients. Herpes simplex virus (HSV) reactivations are usually prevented by acyclovir (ACV) prophylaxis, whereas cidofovir (CDV) has been used off indication to manage AdV infections. We report a child with myelodysplastic syndrome undergoing multiple SCT, who experienced HSV-1 disease including severe mucositis and herpetic whitlow, as well as high viral load AdV DNAemia. Both ACV and CDV were ineffective; however, viral loads were decreased with brincidofovir, resulting in viral clearance. A subsequent Epstein-Barr virus disease with relevant meningoencephalitis responded to rituximab.

Approved Antiviral Drugs over the Past 50 Years

Since the first antiviral drug, idoxuridine, was approved in 1963, 90 antiviral drugs categorized into 13 functional groups have been formally approved for the treatment of the following 9 human infectious diseases: (i) HIV infections (protease inhibitors, integrase inhibitors, entry inhibitors, nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and acyclic nucleoside phosphonate analogues), (ii) hepatitis B virus (HBV) infections (lamivudine, interferons, nucleoside analogues, and acyclic nucleoside phosphonate analogues), (iii) hepatitis C virus (HCV) infections (ribavirin, interferons, NS3/4A protease inhibitors, NS5A inhibitors, and NS5B polymerase inhibitors), (iv) herpesvirus infections (5-substituted 2'-deoxyuridine analogues, entry inhibitors, nucleoside analogues, pyrophosphate analogues, and acyclic guanosine analogues), (v) influenza virus infections (ribavirin, matrix 2 protein inhibitors, RNA polymerase inhibitors, and neuraminidase inhibitors), (vi) human cytomegalovirus infections (acyclic guanosine analogues, acyclic nucleoside phosphonate analogues, pyrophosphate analogues, and oligonucleotides), (vii) varicella-zoster virus infections (acyclic guanosine analogues, nucleoside analogues, 5-substituted 2'-deoxyuridine analogues, and antibodies), (viii) respiratory syncytial virus infections (ribavirin and antibodies), and (ix) external anogenital warts caused by human papillomavirus infections (imiquimod, sinecatechins, and podofilox). Here, we present for the first time a comprehensive overview of antiviral drugs approved over the past 50 years, shedding light on the development of effective antiviral treatments against current and emerging infectious diseases worldwide.

Progress in Treatment of Viral Infections in Children with Acute Lymphoblastic Leukemia

In children, the most commonly encountered type of leukemia is acute lymphoblastic leukemia (ALL). An important source of morbidity and mortality in ALL are viral infections. Even though allogeneic transplantations, which are often applied also in ALL, carry a recognized risk for viral infections, there are multiple factors that make ALL patients susceptible to viral infections. The presence of those factors has an influence in the type and severity of infections. Currently available treatment options do not guarantee a positive outcome for every case of viral infection in ALL, without significant side effects. Side effects can have very serious consequences for the ALL patients, which include nephrotoxicity. For this reason a number of strategies for personalized intervention have been already clinically tested, and experimental approaches are being developed. Adoptive immunotherapy, which entails administration of ex vivo grown immune cells to a patient, is a promising approach in general, and for transplant recipients in particular. The ex vivo grown cells are aimed to strengthen the immune response to the virus that has been identified in the patients' blood and tissue samples. Even though many patients with weakened immune system can benefit from progress in novel approaches, a viral infection still poses a very significant risk for many patients. Therefore, preventive measures and supportive care are very important for ALL patients.

Outbreak of acute febrile respiratory illness caused by human adenovirus B P14H11F14 in a military training camp in Shandong China

This study reports an outbreak of acute febrile respiratory illness caused by human adenovirus B [P14H11F14] in a military training center in China between May and June 2014. In total, 164 military personnel were affected, and two patients were admitted into the intensive care unit of the military regional central hospital. A HAdV-B [P14H11F14] virus was confirmed as the etiological pathogen of this acute outbreak of febrile respiratory illness based on clinical manifestations, epidemiological characteristics, specific molecular detection results, phylogenetic analysis, and serological assays. The virus was isolated by the rhabdomyosarcoma cell culture method, and the complete sequences of the E1A, penton base, hexon, and fiber genes were determined and deposited in the GenBank database. Phylogenetic and sequence homology analyses indicated that the isolated strain is most closely related to some HAdV-55 strains from mainland China. However, this strain appeared to be less virulent than former HAdV-55 strains. According to the chest X-ray results of 31 affected patients, there was no radiological evidence of pneumonia. The most frequent symptoms in these patients were sore throat (95.12 %, 156/164) and tonsillitis (93.29 %, 153/164). During the course of the outbreak, incorrect response measures and some potential risk factors, such as fire training and marching training, may have exacerbated the spread of the infection. This outbreak illustrates the urgent need to improve the epidemiological and etiological surveillance of HAdV infections and to improve the ability of doctors and health officials in basic units of the Chinese army to respond effectively to febrile respiratory illness.

Laboratory Diagnosis of Infections in Cancer Patients: Challenges and Opportunities

Infections remain a significant cause of morbidity and mortality in cancer patients. The differential diagnosis for these patients is often wide, and the timely selection of the right clinical tests can have a significant impact on their survival. However, laboratory findings with current methodologies are often negative, challenging clinicians and laboratorians to continue the search for the responsible pathogen. Novel methodologies are providing increased sensitivity and rapid turnaround time to results but also challenging our interpretation of what is a clinically significant pathogen in cancer patients. This minireview provides an overview of the most common infections in cancer patients and discusses some of the challenges and opportunities for the clinical microbiologist supporting the care of cancer patients.

The adenovirus E4-ORF3 protein functions as a SUMO E3 ligase for TIF-1γ sumoylation and poly-SUMO chain elongation

The adenovirus (Ad) early region 4 (E4)-ORF3 protein regulates diverse cellular processes to optimize the host environment for the establishment of Ad replication. E4-ORF3 self-assembles into multimers to form a nuclear scaffold in infected cells and creates distinct binding interfaces for different cellular target proteins. Previous studies have shown that the Ad5 E4-ORF3 protein induces sumoylation of multiple cellular proteins and subsequent proteasomal degradation of some of them, but the detailed mechanism of E4-ORF3 function remained unknown. Here, we investigate the role of E4-ORF3 in the sumoylation process by using transcription intermediary factor (TIF)-1γ as a substrate. Remarkably, we discovered that purified E4-ORF3 protein stimulates TIF-1γ sumoylation in vitro, demonstrating that E4-ORF3 acts as a small ubiquitin-like modifier (SUMO) E3 ligase. Furthermore, E4-ORF3 significantly increases poly-SUMO3 chain formation in vitro in the absence of substrate, showing that E4-ORF3 has SUMO E4 elongase activity. An E4-ORF3 mutant, which is defective in protein multimerization, exhibited severely decreased activity, demonstrating that E4-ORF3 self-assembly is required for these activities. Using a SUMO3 mutant, K11R, we found that E4-ORF3 facilitates the initial acceptor SUMO3 conjugation to TIF-1γ as well as poly-SUMO chain elongation. The E4-ORF3 protein displays no SUMO-targeted ubiquitin ligase activity in our assay system. These studies reveal the mechanism by which E4-ORF3 targets specific cellular proteins for sumoylation and proteasomal degradation and provide significant insight into how a small viral protein can play a role as a SUMO E3 ligase and E4-like SUMO elongase to impact a variety of cellular responses.

The extracellular interactome of the human adenovirus family reveals diverse strategies for immunomodulation

Viruses encode secreted and cell-surface expressed proteins essential to modulate host immune defenses and establish productive infections. However, to date there has been no systematic study of the extracellular interactome of any human virus. Here we utilize the E3 proteins, diverse and rapidly evolving transmembrane-containing proteins encoded by human adenoviruses, as a model system to survey the extracellular immunomodulatory landscape. From a large-scale protein interaction screen against a microarray of more than 1,500 human proteins, we find and validate 51 previously unidentified virus–host interactions. Our results uncover conserved strategies as well as substantial diversity and multifunctionality in host targeting within and between viral species. Prominent modulation of the leukocyte immunoglobulin-like and signalling lymphocyte activation molecule families and a number of inhibitory receptors were identified as hubs for viral perturbation, suggesting unrecognized immunoregulatory strategies. We describe a virus–host extracellular interaction map of unprecedented scale that provides new insights into viral immunomodulation.

Viruses interact with their hosts via secreted and membrane-bound proteins to affect host immune responses and virulence. Here the authors contribute to our understanding of this relationship with an extracellular interaction map of human and adenoviral E3 immunomodulatory proteins.

Distribution and Molecular Characterization of Human Adenovirus and Epstein-Barr Virus Infections in Tonsillar Lymphocytes Isolated from Patients Diagnosed with Tonsillar Diseases

Surgically removed palatine tonsils provide a conveniently accessible source of T and B lymphocytes to study the interplay between foreign pathogens and the host immune system. In this study we have characterised the distribution of human adenovirus (HAdV), Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) in purified tonsillar T and B cell-enriched fractions isolated from three patient age groups diagnosed with tonsillar hypertrophy and chronic/recurrent tonsillitis. HAdV DNA was detected in 93 out of 111 patients (84%), while EBV DNA was detected in 58 patients (52%). The most abundant adenovirus type was HAdV-5 (68%). None of the patients were positive for HCMV. Furthermore, 43 patients (39%) showed a co-infection of HAdV and EBV. The majority of young patients diagnosed with tonsillar hypertrophy were positive for HAdV, whereas all adult patients diagnosed with chronic/recurrent tonsillitis were positive for either HAdV or EBV. Most of the tonsils from patients diagnosed with either tonsillar hypertrophy or chronic/recurrent tonsillitis showed a higher HAdV DNA copy number in T compared to B cell-enriched fraction. Interestingly, in the majority of the tonsils from patients with chronic/recurrent tonsillitis HAdV DNA was detected in T cells only, whereas hypertrophic tonsils demonstrated HAdV DNA in both T and B cell-enriched fractions. In contrast, the majority of EBV positive tonsils revealed a preference for EBV DNA accumulation in the B cell-enriched fraction compared to T cell fraction irrespective of the patients' age.

An adenovirus 4 outbreak amongst staff in a pediatric ward manifesting as keratoconjunctivitis-a possible failure of contact and aerosol infection control

An adenovirus serotype 4 outbreak was identified on a pediatric ward involving 4 members of the health care staff. Two inpatients on the ward at the time (1 immunocompromised) were shedding this virus from their respiratory tracts and could have acted as independent index cases for the staff infections. Significantly, upon investigation, it was found that staff members were unaware that adenoviruses are not completely eliminated by alcohol gel handrubs and that soap and water handwashing is also required.

Epidemiology and Clinical Characteristics of Respiratory Infections Due to Adenovirus in Children Living in Milan, Italy, during 2013 and 2014

To evaluate the predominant human adenovirus (HAdV) species and types associated with pediatric respiratory infections, nasopharyngeal swabs were collected from otherwise healthy children attending an emergency room in Milan, Italy, due to a respiratory tract infection from January 1 to February 28 of two subsequent years, 2013 and 2014. The HAdVs were detected using a respiratory virus panel fast assay (xTAG RVP FAST v2) and with a HAdV-specific real-time polymerase chain reaction; their nucleotides were sequenced, and they were tested for positive selection. Among 307 nasopharyngeal samples, 61 (19.9%) tested positive for HAdV. HAdV was the only virus detected in 31/61 (50.8%) cases, whereas it was found in association with one other virus in 25 (41.0%) cases and with two or more viruses in 5 (8.2%) cases. Human Enterovirus/human rhinovirus and respiratory syncytial virus were the most common co-infecting viral agents and were found in 12 (19.7%) and 7 (11.5%) samples, respectively. Overall, the HAdV strain sequences analyzed were highly conserved. In comparison to HAdV-negative children, those infected with HAdV had a reduced frequency of lower respiratory tract involvement (36.1% vs 55.2%; p = 0.007), wheezing (0.0% vs 12.5%; p = 0.004), and hospitalization (27.9% vs 56.1%; p<0.001). Antibiotic therapy and white blood cell counts were more frequently prescribed (91.9% vs 57.1%; p = 0.04) and higher (17,244 ± 7,737 vs 9,565 ± 3,211 cells/μL; p = 0.04), respectively, in children infected by HAdV-C than among those infected by HAdV-B. On the contrary, those infected by HAdV-B had more frequently lower respiratory tract involvement (57.1% vs 29.7%) but difference did not reach statistical significant (p = 0.21). Children with high viral load were absent from child care attendance for a longer period of time (14.5 ± 7.5 vs 5.5 ± 3.2 days; p = 0.002) and had higher C reactive protein levels (41.3 ± 78.5 vs 5.4 ± 9.6 μg/dL; p = 0.03). This study has shown that HAdV infections are diagnosed more commonly than usually thought and that HAdVs are stable infectious agents that do not frequently cause severe diseases. A trend toward more complex disease in cases due to HAdV species C and in those with higher viral load was demonstrated. However, further studies are needed to clarify factors contributing to disease severity to understand how to develop adequate preventive and therapeutic measures.

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.

Detection and Molecular Typing of Human Adenoviruses Associated with Respiratory Illnesses in Kerala

Adenoviruses are responsible for approximately 5-10% of acute respiratory infections globally. However, there are a limited number of reports on the types of circulating respiratory human adenoviruses (HAdV) in India. We detected HAdV in the post-mortem specimens of a young child who died as a result of an acute febrile illness. To retrospectively investigate the circulating adenovirus types in the Alappuzha region, samples (n = 235) collected from patients with influenza-like illnesses who participated in the influenza surveillance program were screened for HAdV. Fourteen samples were identified as positive for adenovirus by PCR analysis. Adenovirus was isolated from 3 of the 14 PCR-positive samples cultured using HEK-293 cell lines. The viral strains isolated in the study were from children between 6 and 10 years of age. The isolates were identified as adenovirus species C and E. Sequencing analysis of the fiber gene and a BLAST search revealed that 2 of the isolates were type HAdV-C2, and the third isolate was a HAdV-E4. A fiber gene sequence-based phylogenetic tree showed that the HAdV-E4 isolate was similar to the Japanese HAdV-E4 strain, whereas the HAdV-C2 isolates formed a distinct cluster. Respiratory infections due to HAdV-E4 are generally observed in adults; this study is the first to demonstrate the involvement of the HAdV-E4 strain in respiratory illnesses in children.

Phylogenetic evidence for intratypic recombinant events in a novel human adenovirus C that causes severe acute respiratory infection in children

Human adenoviruses (HAdVs) are prevalent in hospitalized children with severe acute respiratory infection (SARI). Here, we report a unique recombinant HAdV strain (CBJ113) isolated from a HAdV-positive child with SARI. The whole-genome sequence was determined using Sanger sequencing and high-throughput sequencing. A phylogenetic analysis of the complete genome indicated that the CBJ113 strain shares a common origin with HAdV-C2, HAdV-C6, HAdV-C1, HAdV-C5, and HAdV-C57 and formed a novel subclade on the same branch as other HAdV-C subtypes. BootScan and single nucleotide polymorphism analyses showed that the CBJ113 genome has an intra-subtype recombinant structure and comprises gene regions mainly originating from two circulating viral strains: HAdV-1 and HAdV-2. The parental penton base, pVI, and DBP genes of the recombinant strain clustered with the HAdV-1 prototype strain, and the E1B, hexon, fiber, and 100 K genes of the recombinant clustered within the HAdV-2 subtype, meanwhile the E4orf1 and DNA polymerase genes of the recombinant shared the greatest similarity with those of HAdV-5 and HAdV-6, respectively. All of these findings provide insight into our understanding of the dynamics of the complexity of the HAdV-C epidemic. More extensive studies should address the pathogenicity and clinical characteristics of the novel recombinant.

Outbreak of adenovirus type 55 infection in Israel

BACKGROUND

Different types of adenoviruses are associated with diverse diseases and with varied disease severity. Adenovirus 55 could be associated with severe respiratory infections.

OBJECTIVES

Here, we report on an adenovirus 55 outbreak in two psychiatric institutions in Israel. The objective of this study was to investigate the adenovirus 55 outbreak.

STUDY DESIGN

We studied the clinical parameters of the patients and sequencing analysis of certain parts of the virus gene was performed.

RESULTS

We identified the first patient who developed symptoms (the index case) and we showed that while both patients and staff members of the institutions were infected, the disease in the psychiatric patients was more severe. We attributed these differences to their mental and underlying health conditions.

CONCLUSIONS

It is important to monitor for adenovirus infection in the community, especially in mental health institutions to allow appropriate medical care.

Cutaneous involvement of disseminated adenovirus infection in an allogeneic stem cell transplant recipient

Infection by human adenoviruses can lead to significant morbidity and mortality in immunocompromised hosts, such as allogeneic stem cell transplant (SCT) recipients, with limited effective treatment options. Specific cutaneous manifestations of disseminated adenovirus infection are not well described. We report a woman in her twenties who received an allogeneic T-cell-depleted peripheral blood SCT for the treatment of severe aplastic anaemia and, 5 months post-transplant, was hospitalized for severe systemic adenovirus infection with progressive involvement of the colon, liver and lungs. Despite therapy with intravenous cidofovir, oral brincidofovir and intravenous immunoglobulin, she had progression of adenoviraemia and dissemination of adenoviral disease. The patient developed a progressive rash characterized by keratotic papules that began on the palms and soles and spread to the entire body. Histopathological examination of skin biopsies of individual skin lesions from the palm and abdomen showed focal acantholytic dyskeratosis and keratinocytes with hyperchromatic nuclei. Several keratinocyte nuclei were immunoreactive for adenovirus. The patient was further treated with ribavirin and adenovirus-specific cytotoxic T lymphocytes but experienced multisystem progression of adenovirus infection culminating in death.

The Adenovirus E4orf4 Protein Provides a Novel Mechanism for Inhibition of the DNA Damage Response

The DNA damage response (DDR) is a conglomerate of pathways designed to detect DNA damage and signal its presence to cell cycle checkpoints and to the repair machinery, allowing the cell to pause and mend the damage, or if the damage is too severe, to trigger apoptosis or senescence. Various DDR branches are regulated by kinases of the phosphatidylinositol 3-kinase-like protein kinase family, including ataxia-telangiectasia mutated (ATM) and ATM- and Rad3-related (ATR). Replication intermediates and linear double-stranded genomes of DNA viruses are perceived by the cell as DNA damage and activate the DDR. If allowed to operate, the DDR will stimulate ligation of viral genomes and will inhibit virus replication. To prevent this outcome, many DNA viruses evolved ways to limit the DDR. As part of its attack on the DDR, adenovirus utilizes various viral proteins to cause degradation of DDR proteins and to sequester the MRN damage sensor outside virus replication centers. Here we show that adenovirus evolved yet another novel mechanism to inhibit the DDR. The E4orf4 protein, together with its cellular partner PP2A, reduces phosphorylation of ATM and ATR substrates in virus-infected cells and in cells treated with DNA damaging drugs, and causes accumulation of damaged DNA in the drug-treated cells. ATM and ATR are not mutually required for inhibition of their signaling pathways by E4orf4. ATM and ATR deficiency as well as E4orf4 expression enhance infection efficiency. Furthermore, E4orf4, previously reported to induce cancer-specific cell death when expressed alone, sensitizes cells to killing by sub-lethal concentrations of DNA damaging drugs, likely because it inhibits DNA damage repair. These findings provide one explanation for the cancer-specificity of E4orf4-induced cell death as many cancers have DDR deficiencies leading to increased reliance on the remaining intact DDR pathways and to enhanced susceptibility to DDR inhibitors such as E4orf4. Thus DDR inhibition by E4orf4 contributes both to the efficiency of adenovirus replication and to the ability of E4orf4 to kill cancer cells.

Evaluation of a New Device for Simplifying and Standardizing Stool Sample Preparation for Viral Molecular Testing with Limited Hands-On Time

Sensitive molecular assays have greatly improved the diagnosis of viral gastroenteritis. However, the proper preparation of stool samples for clinical testing remains an issue. bioMérieux has developed a stool preprocessing device (SPD) that includes a spoon for calibrated sampling and a vial containing buffer, glass beads, and two filters. The resulting stool filtrate is used for nucleic acid extraction. The purpose of this study was to evaluate the performance of the SPD for the quantification of human adenovirus (HAdV) DNA in stool samples collected from hematopoietic stem cell transplant (HSCT) recipients. HAdV DNA was quantified with the Adenovirus R-gene kit. The suitability of the device to reproducibly quantify HAdV DNA in stools using different extraction platforms (easyMAG and QIAsymphony) was determined using archived HAdV-positive stool samples. Coefficients of variation of HAdV DNA quantifications ranged from 1.79% to 1.83%, and no difference in quantification was observed between the two extraction systems. The HAdV DNA limit of quantification using the SPD was 3.75 log10copies/g of stool. HAdV DNA quantification using the SPD was then compared to that of the routine preprocessing technique on 75 fresh stool samples collected prospectively from pediatric HSCT recipients at risk for HAdV infections. Thirty-eight samples were HAdV DNA positive with both the SPD and routine preprocessing methods. HAdV DNA loads were on average 1.14-log10copies/g of stool higher with the SPD (P< 0.0001) than with routine methods. This new device enabled a standardized preparation of stool samples in <5 min and a reproducible and sensitive quantification of HAdV DNA. The use of the SPD for the detection of other gastrointestinal infections warrants further evaluation.

Antiviral Host Defence Peptides

The ongoing global mortality and morbidity associated with viral pathogens highlights the need for the continued development of effective, novel antiviral molecules. The antiviral activity of cationic host defence peptides is of significant interest as novel therapeutics for treating viral infection and predominantly due to their broad spectrum antiviral activity. These peptides also display powerful immunomodulatory activity and are key mediators of inflammation. Therefore, they offer a significant opportunity to inform the development of novel therapeutics for treating viral infections by either directly targeting the pathogen or by enhancing the innate immune response. In this chapter, we review the antiviral activity of cathelicidins and defensins, and examine the potential for these peptides to be used as novel antiviral agents.