Adenovirus: Epidemiology, Global Spread of Novel Types, and Approach to Treatment

Surveillance of Human Adenovirus Types and the Impact of the COVID-19 Pandemic on Reporting - United States, 2017-2023

Human adenoviruses (HAdVs) are typically associated with mild respiratory illnesses, although severe disease and outbreaks in congregate settings occur. The National Adenovirus Type Reporting System (NATRS) is a passive, laboratory-based surveillance system that monitors trends in circulation of HAdV types in the United States. This report summarizes the distribution of HAdV types reported to NATRS during 2017-2023. During this 7-year period, 2,241 HAdV specimens with typing results were reported to NATRS. The number of specimens with HAdV typing results reported varied annually during 2017-2019 (range = 389-562) and declined during 2020-2023 (range = 58-356). During 2017-2023, six HAdV types (1-4, 7, and 14) accounted for 88.3% of typed specimens reported; 17.0% of specimens were identified as outbreak-related. An increase in type 41 reporting was associated with a hepatitis cluster during 2021-2022. Reporting to NATRS has declined since the COVID-19 pandemic, despite continued HAdV circulation reported through passive laboratory surveillance to the National Respiratory and Enteric Virus Surveillance System. Enhanced participation in NATRS is needed to improve monitoring of circulating HAdV types.

Human adenovirus type 7 (HAdV-7) infection induces pulmonary vascular endothelial injury through the activation of endothelial autophagy

BACKGROUND

HAdV-7 is a prevalent pathogen that can cause severe pneumonia in children. Previous studies have shown a significant increase in serum levels of vascular permeability factor (VPF/VEGF) and viral load in pediatric patients with fatal HAdV-7 infection, suggesting potential damage to the pulmonary vascular endothelium. Further research is necessary to elucidate the underlying mechanism.

METHODS

The human lung microvascular endothelial cell line-5a and human CD46 mice were used for in vitro and in vivo experiments, respectively. RNA-seq was employed for correlative omics analysis. Viral infection and copy status were examined using transmission electron microscopy to observe virus particles, immunofluorescence to detect the viral protein Hexon, and qPCR to assess HAdV-7 fiber gene copies. Various methods, including ELISAs for VEGF and other injury markers, the CCK8 assay for cell viability, and flow cytometry for endothelium numbers, were employed to evaluate endothelial damage. Acute lung injury severity was evaluated by scoring pathological inflammation and measuring pulmonary vascular permeability. Autophagy activation was assessed by observing autophagosomes and validating marker proteins.

RESULTS

GSEA analysis showed significant enrichment of gene sets related to endothelial functions (barrier, defense, and regeneration) and ALI in the HAdV-7-infected group. GO analysis indicated an enrichment of autophagy-related pathways linked to cell death. Subsequently, successful signs of HAdV-7 infection and replication were observed in the endothelium, including cytopathic effects, intracellular virions, and increased HAdV-7 fiber gene copies. Endothelial injury, including mitochondrial damage, decreased endothelium, and elevated levels of endothelial injury markers such as VEGF, sICAM-1, sVCAM-1, E-selectin, ESM1, MCP1, and IL1β were observed after HAdV-7 infection. Additionally, evidence of leaky lung blood vessels and ALI was observed, including progressive weight loss, elevated pulmonary vascular permeability, and severe lung consolidation. Furthermore, HAdV-7 infection induced autophagosome formation in the endothelium and triggered complete cell autophagy. Importantly, inhibiting autophagic flux reduced VEGF levels and other endothelial injury markers, decreased viral load, improved cell survival rate, alleviated pulmonary vessel leakage, and mitigated lung inflammation.

CONCLUSIONS

HAdV-7 successfully infects pulmonary vascular endothelium and replicates effectively, causing injury to the endothelium, high VEGF expression and viral load in the serum, as well as ALI/ARDS. Autophagy inhibitors can alleviate endothelial injury, inhibit viral replication, relieve leakage from the vasculature, and reduce lung inflammation.

Screening and verification of differentially expressed serum proteins in children with severe adenovirus pneumonia

Background

Human adenoviruses are prevalent pathogens that cause severe acute respiratory infections. The clinical presentation of the adenoviral pneumonia is varied; in severe cases, they may cause systemic multi-system damages. Currently, early clinical differential diagnosis is difficult under the existing testing methods, the study identified potential biomarkers by screening and validating differentially expressed proteins (DEPs), and aimed at distinguishing between severe and non-severe adenovirus pneumonia in children aged <14 years.

Methods

DEPs were identified using data-independent acquisition (DIA) quantitative proteomics technology, and potential biomarkers were further validated using an enzyme-linked immunosorbent assay (ELISA).

Results

Twenty-seven identical DEPs were found in patients with severe adenovirus pneumonia. Among these, 10 were downregulated, and 17 were upregulated. In the protein-protein interaction network, five proteins were located at the center of the functional network. Among these, E-selectin showed significantly higher serum expression levels in the severe adenoviral pneumonia group than in adenoviral pneumonia and control groups (p < 0.001). ELISA results were consistent with the proteomic analyses. The receiver operating characteristic (ROC) curve for E-selectin revealed a sensitivity of 79.31% and a specificity of 96.55%, with an area under the curve (AUC) of 0.92.

Conclusion

E-selectin has potential as a novel biomarker for severe adenoviral pneumonia, and offers insights for improved diagnosis and clinical management.

A humanized neutralizing antibody protects against human adenovirus type 7 infection in humanized desmoglein-2 and CD46 double-receptor transgenic mice

BACKGROUND

Human adenovirus type 7 (HAdV7) has become a major public health threat due to its widespread transmission, severe associated pneumonia, and a lack of effective anti-HAdV7 drugs. The aim of the current study is to design a humanized monoclonal antibody (mAb) demonstrating efficacy against HAdV-7 infections in vitro and in vivo.

METHODS

The humanized neutralizing antibody, 3G5-hu, was derived from the murine mAb 3G5. Antibody activity was evaluated using a flow cytometry-based neutralization (FCN) assay to identify humanized mAbs retaining potent neutralizing activity. Additionally, a humanized hDSG2/hCD46 dual-receptor transgenic mouse model was developed to simulate HAdV-7 infection.

RESULTS

Using recombinant HAdV-7 expressing enhanced green fluorescent protein and clinically isolated wild-type HAdV-7, the half-maximal effective concentration of 3G5-hu against HAdV-7 was determined to be < 30 ng/mL. Notably, 3G5-hu exhibits high specificity for the hexon protein of the HAdV-7 capsid (affinity: KD = 9.02 × 10- 11 M). Microneutralization studies with wild-type HAdV-7 and rAd7EGFP confirmed that humanized mAb 3G5-hu neutralizes 10-30 ng/mL HAdV-7 (approximately 67-200 pM). Furthermore, hDSG2/hCD46 double-receptor transgenic mice are more susceptible to HAdV-7 infection than single-receptor transgenic mice. Meanwhile, the humanized mAb 3G5-hu provides good protection against HAdV-7 infection in hDSG2/hCD46 knock-in transgenic mice.

CONCLUSIONS

The newly designed humanized mAb 3G5-hu specifically neutralizes HAdV-7 in vitro and in vivo. 3G5-hu elicits protection against HAdV-7 infection in hDSG2/hCD46 knock-in transgenic mice. The findings of this study provide insights to guide the future development of preventative and therapeutic treatments for HAdV-7 infection.

Synthesis of USC-093 and comparison with its promoiety enantiomer USC-093D against adenovirus in vitro and in a Syrian hamster model

Adenovirus infections of immunocompromised humans are a significant source of morbidity and mortality. At present, no drug has been approved by FDA for the treatment of adenovirus infections. A current treatment of such infections is off-label use of an antiviral acyclic nucleotide phosphonate, cidofovir (CDV, ( S )-HPMPC), which requires i.v. administration and has dose-limiting kidney toxicity. We recently reported that USC-093, a homoserinamide analogue of the tyrosinamide ( S )- HPMPA prodrug USC-087, was orally effective at a 10 mg/kg against disseminated human adenovirus infection (HAdV-C6) in a Syrian hamster model, although their efficacy was marginal after respiratory infection. Neither prodrug manifested GI toxicity. Unlike USC-087, USC-093 showed no significant nephrotoxicity at the effective dose. Here, we describe in detail the synthesis of USC-093 and also its D-homoserinamide analogue, USC-093D, in four steps (20-40% overall yield) starting from Boc-protected L-homoserine or D-homoserine lactone, respectively. The two stereoisomeric prodrugs had EC 50 30-70 nM vs. Ad5 or 1-6 nM vs. Ad6 in HFF cells, with USC-093D giving the lower values. The prodrugs were 30-59x more potent vs. Ad5 and 82-332x more potent than Ad6 relative to the positive control, CDV. To ascertain whether D-chirality in the promoiety could enhance the performance of the prodrug in vivo, USC-093D and USC-093 were compared in the Syrian hamster model (treated from day 1 q.d at an experimentally determined maximum tolerated oral dose of 20 mg/kg)). In this study, the hamsters were instilled i.n. with vehicle or 4X10 10 PFU/kg of HAdV-C6 to promote lung infection. Oral valganciclovir (VGCV) at 200 mg/kg b.i.d. was used as the positive control. The body weights were recorded daily, and at 3 days post challenge, gross pathological observation was performed. Lung samples were collected, and the virus burden was determined by TCID 50 assay. The results show that altering homoserine stereochemistry did not markedly improve the efficacy of the orally administered prodrug, consistent with the premise that its mechanism of transport is likely not dependent on stereoselective pathways, such as hPEPT1-mediated uptake.

Epidemiological and clinical characteristics of adenovirus-associated respiratory tract infection in children in Hangzhou, China, 2019-2024

This study aimed to assess the impact of COVID-19 on the prevalence of adenovirus (AdV) infection in children. This study retrospectively analyzed the changes in the epidemiological and clinical features of AdV-associated respiratory infections in children in Hangzhou, China, between January 2019 and July 2024. A total of 771 316 samples were included in the study, and the positive rate was 6.10% (47 050/771 316). Among them, the positive rate of AdV infection was highest in 2019, reaching 11.29% (26 929/238 333), while the positive rates in the remaining years were between 2% and 9%. In terms of seasonal epidemic characteristics, the summer of 2019 was the peak of AdV incidence, with the positive rate peaking at around 16.95% (7275/45 268), followed by a gradual decline and a low-level epidemic in winter, with a positive rate of 8.79% (8094/92 060). However, during the period 2020-2024, the AdV epidemic season did not show any significant regularity. Gender analysis revealed that the positive rate of male patients was generally greater than that of female patients. In different age groups, the population susceptible to AdV changed before and after the epidemic. In the early and middle stages of the COVID-19 epidemic, the susceptible population was mainly 2-5 years old, whereas in the later stages of the epidemic, the susceptible population was 5-18 years old. In addition, the main clinical symptoms of AdV-positive children from 2019-2024 were respiratory tract symptoms and fever. In summary, the COVID-19 epidemic has had a certain impact on the prevalence of AdV. These findings provide an important basis and reference for the prevention and diagnosis of AdV, especially in the context of increasing age- and gender-specific public health strategies.

Evolution of Treatment Modalities for Disseminated HAdV Infection in Neonates

Human adenovirus (HAdV) infection in newborns is a rare condition that typically affects multiple organ systems and has a high mortality rate. We report a case of neonatal HAdV-D37 infection that presented with fever and respiratory distress that was confirmed by metagenomic next-generation sequencing using blood and bronchoalveolar lavage fluid. We treated the patient with intravenous immunoglobulin, methylprednisolone, and anticoagulants, and the patient recovered. Our review of 41 cases of HAdV found that treatment with intravenous immunoglobin might have improved the outcome of HAdV-D infection. We further suggest that glucocorticoid therapy may have additional therapeutic validity in the setting of severe or disseminated disease and that monitoring coagulation function and timely anticoagulation treatment should be considered to prevent complications associated with disseminated intravascular coagulation.

Viral etiologies of acute liver failure

Acute liver failure (ALF) is a rare cause of liver-related mortality worldwide, with an estimated annual global incidence of more than one million cases. While drug-induced liver injury, including acetaminophen toxicity, is the leading cause of ALF in the Western world, viral infections remain a significant cause of ALF and the most common cause in many developing nations. Given the high mortality rates associated with ALF, healthcare providers should be aware of the broad range of viral infections that have been implicated to enable early diagnosis, rapid treatment initiation when possible, and optimal management, which may include liver transplantation. This review aims to provide a summary of viral causes of ALF, diagnostic approaches, treatment options, and expected outcomes.

Adenovirus infections: new insights for the clinical laboratory

Since their discovery in 1953, research on human adenoviruses (HAdVs) has had diverse foci, resulted in groundbreaking discoveries, such as gene splicing, and generated powerful oncolytic constructs and expression vectors for vaccine development and gene therapy. In contrast, virologists working in this field have made relatively little progress toward the prevention and treatment of the wide spectrum of HAdV-associated diseases. The understanding of species-specific features of viral pathogenesis, or of the mechanisms underlying the establishment of latency and reactivation, is still limited. This group of viruses currently comprises 7 species, 51 serotypes, and 116 unique genotypes. This complexity manifests with a challenging pathophenotypic diversity. Some types are highly virulent, and others do not seem to cause disease in immunocompetent hosts. The assessment of viral load in blood and respiratory specimens has well-acknowledged clinical utility, but the lack of virus typing capabilities easily implementable in clinical laboratories represents a lingering major limitation to the interpretation of positive tests. Some HAdV infections do have severe consequences for both immunocompetent and immunocompromised patients, and the understanding of why this is the case will require more research. Clinical isolates and collections of positive specimens can provide unique resources to investigate the molecular bases of viral virulence and fitness and also help gather information of spatial-temporal patterns of viral circulation in susceptible communities, but they are extremely scarce. Clinical laboratories are underutilized interfaces between patients and academic scientists and have, therefore, a high potential to become valuable collaborators in research moving forward.

Proportions and Seasonal Patterns of Respiratory Viruses via Rapid Tests in Adults at a Greek Hospital (Oct. 2023-Mar. 2024)

BACKGROUND

Respiratory infections pose a major public health threat. The predominant viruses causing viral respiratory infections are influenza A and B (Flu-A, Flu-B), coronaviruses, respiratory syncytial virus (RSV), and adenovirus. This study aims to investigate the proportion of these cases via rapid antigen tests and assess seasonal patterns.

METHODS

Clinical samples were collected from symptomatic adults presenting to the Emergency and Respiratory Medicine Departments of the University Hospital of Larissa (UHL), Greece from 16 October 2023 to 31 March 2024. Nasal specimens were antigen-tested for Flu-A/B, SARS-CoV-2, RSV, and adenovirus.

RESULTS

The total sample of specimens collected was 1434, of which 739 (51.5%) were female and 695 were male (48.5%). The mean age of participants was 57 ± 5.5 years. Among the positive results, we recorded a proportion of 40.18% and 11.40% for influenza A and B, respectively, followed by 35.79% for SARS-CoV-2, 10.70% for RSV, and 1.93% for adenovirus.

CONCLUSIONS

In Greece, surveillance systems in infection control are underutilized. Rapid tests via multiple antigens can quickly identify viral infections, making them a valuable tool with financial benefits for health systems. Early detection of respiratory infections helps allocate resources efficiently, ensures adequate staff and facilities are available, and improves patient care through refined clinical management.

Trends in Viral Vector-Based Vaccines for Tuberculosis: A Patent Review (2010-2023)

Tuberculosis (TB) is an ancient global public health problem. Several strategies have been applied to develop new and more effective vaccines against TB, from attenuated or inactivated mycobacteria to recombinant subunit or genetic vaccines, including viral vectors. This review aimed to evaluate patents filed between 2010 and 2023 for TB vaccine candidates. It focuses on viral vector-based strategies. A search was carried out in Espacenet, using the descriptors "mycobacterium and tuberculosis" and the classification A61K39. Of the 411 patents preliminarily identified, the majority were related to subunit vaccines, with 10 patents based on viral vector platforms selected in this study. Most of the identified patents belong to the United States or China, with a concentration of patent filings between 2013 and 2023. Adenoviruses were the most explored viral vectors, and the most common immunodominant Mycobacterium tuberculosis (Mtb) antigens were present in all the selected patents. The majority of patents were tested in mouse models by intranasal or subcutaneous route of immunization. In the coming years, an increased use of this platform for prophylactic and/or therapeutic approaches for TB and other diseases is expected. Along with this, expanding knowledge about the safety of this technology is essential to advance its use.

Longitudinal Monitoring of the Effects of Anti-Adenoviral Treatment Regimens in a Permissive In Vivo Model

Adenovirus infections of immunocompromised patients can cause life-threatening disseminated disease. While there are presently no drugs specifically approved to treat these infections, there are several compounds that showed efficacy against adenovirus in preclinical studies. For any such compound, low toxicity is an essential requirement. As cumulative drug effects can accentuate pathology, especially in patients with other morbidities, it is important to limit antiviral exposure to what is absolutely necessary. This is achievable by monitoring the virus burden of the patients and administering antivirals to suppress virus replication to a non-pathogenic level. We modeled such a system using Syrian hamsters infected with a replication-competent adenovirus vector, in which luciferase expression is coupled to virus replication. We found that virus replication could be followed in vivo in the same animal by repeated measurement of luciferase expression. To test the utility of an interrupted treatment regimen, we used NPP-669 and valganciclovir, two antiviral compounds with high and moderate anti-adenoviral efficacy, respectively. We found that short-term treatment of adenovirus-infected hamsters at times of peak virus replication can prevent virus-associated pathology. Thus, we believe that this animal model can be used to model different treatment regimens for anti-adenoviral compounds.

Retrospective analysis of hospital electronic health records reveals unseen cases of acute hepatitis with unknown aetiology in adults in Oxfordshire

BACKGROUND

An outbreak of acute severe hepatitis of unknown aetiology (AS-Hep-UA) in children during 2022 was subsequently linked to infections with adenovirus-associated virus 2 and other 'helper viruses', including human adenovirus. It is possible that evidence of such an outbreak could be identified at a population level based on routine data captured by electronic health records (EHR).

METHODS

We used anonymised EHR to collate retrospective data for all emergency presentations to Oxford University Hospitals NHS Foundation Trust in the UK, between 2016-2022, for all ages from 18 months and older. We investigated clinical characteristics and temporal distribution of presentations of acute hepatitis and of adenovirus infections based on laboratory data and clinical coding. We relaxed the stringent case definition adopted during the AS-Hep-UA to identify all cases of acute hepatitis with unknown aetiology (termed AHUA). We compared events within the outbreak period (defined as 1st Oct 2021-31 Aug 2022) to the rest of our study period.

RESULTS

Over the study period, there were 903,433 acute presentations overall, of which 391 (0.04%) were classified as AHUA. AHUA episodes had significantly higher critical care admission rates (p < 0.0001, OR = 41.7, 95% CI:26.3-65.0) and longer inpatient admissions (p < 0.0001) compared with the rest of the patient population. During the outbreak period, significantly more adults (≥ 16 years) were diagnosed with AHUA (p < 0.0001, OR = 3.01, 95% CI: 2.20-4.12), and there were significantly more human adenovirus (HadV) infections in children (p < 0.001, OR = 1.78, 95% CI:1.27-2.47). There were also more HAdV tests performed during the outbreak (p < 0.0001, OR = 1.27, 95% CI:1.17-1.37). Among 3,707 individuals who were tested for HAdV, 179 (4.8%) were positive. However, there was no evidence of more acute hepatitis or increased severity of illness in HadV-positive compared to negative cases.

CONCLUSIONS

Our results highlight an increase in AHUA in adults coinciding with the period of the outbreak in children, but not linked to documented HAdV infection. Tracking changes in routinely collected clinical data through EHR could be used to support outbreak surveillance.

NPP-669, a prodrug of cidofovir, is highly efficacious against human adenovirus infection in the permissive Syrian hamster model

Human adenoviruses can cause serious, disseminated infections in immunocompromised patients. For pediatric allogeneic stem cell transplant patients, the case fatality rate can reach 80%. Still, there is no available antiviral drug that is specifically approved by the Food and Drug Administration for the treatment of adenovirus infections. To fill this pressing medical need, we have developed NPP-669, a prodrug of cidofovir with broad activity against double-stranded DNA viruses, including adenoviruses. Here, we report on the in vivo anti-adenoviral efficacy of NPP-669. Using the immunosuppressed Syrian hamster as the model, we show that NPP-669 is highly efficacious when dosed orally at 1 mg/kg and 3 mg/kg. In a delayed administration experiment, NPP-669 was more effective than brincidofovir, a similar compound that reached Phase III clinical trials. Furthermore, parenteral administration of NPP-669 increased its efficacy approximately 10-fold compared to oral dosing without apparent toxicity, suggesting that this route may be preferable in a hospital setting. Based on these findings, we believe that NPP-669 is a promising new compound that needs to be further investigated.

High-Frequency Recombination of Human Adenovirus in Children with Acute Respiratory Tract Infections in Beijing, China

Recombination events in human adenovirus (HAdV) have led to some new highly pathogenic or infectious types. It is vital to monitor recombinant HAdVs, especially in children with acute respiratory tract infections (ARIs). In the retrospective study, HAdV positive specimens were collected from pediatric patients with ARIs during 2015 to 2021, then typed by sequence analysis of the penton base, hexon and fiber gene sequence. For those with inconsistent typing results, a modified method with species-specific primer sets of a fiber gene sequence was developed to distinguish co-infections of different types from recombinant HAdV infections. Then, plaque assays combined with meta-genomic next-generation sequencing (mNGS) were used to reveal the HAdV genomic characteristics. There were 466 cases positive for HAdV DNA (2.89%, 466/16,097) and 350 (75.11%, 350/466) successfully typed with the most prevalent types HAdV-B3 (56.57%, 198/350) and HAdV-B7 (32.00%, 112/350), followed by HAdV-C1 (6.00%, 21/350). Among 35 cases (7.51%, 35/466) with inconsistent typing results, nine cases were confirmed as co-infections by different types of HAdVs, and 26 cases as recombinant HAdVs in six genetic patterns primarily clustered to species C (25 cases) in pattern 1-5, or species D (1 case) in pattern 6. The novel recombinant HAdV of species D was identified with multiple recombinant events among HAdV-D53, HAdV-D64, and HAdV-D8, and officially named as HAdV-D115. High-frequency recombination of HAdVs in six genetic recombination patterns were identified among children with ARIs in Beijing. Specifically, there is a novel Adenovirus D human/CHN/S8130/2023/115[P22H8F8] designed as HAdV D115.

Approach for defining human adenovirus infection and disease for central review adjudication in clinical studies

BACKGROUND

Pediatric allogeneic hematopoietic cell transplant (allo-HCT) recipients are at risk for morbidity and mortality from human adenovirus (HAdV). HAdV can be detected in an asymptomatic state, referred to as infection or with signs or symptoms of illness, referred to as disease. Standardized case definitions are needed to distinguish infection from disease and allow for consistent reporting in both observational cohort studies and therapeutic clinical trials.

METHODS

A working group of experts in virology, transplant infectious disease, and HCT was assembled to develop HAdV infection and disease definitions with the degree of certainty (i.e., possible, probable, and proven). Definitions were further refined through an iterative process and independently applied by two central review committees (CRCs) to 20 pediatric allo-HCT recipients with at least one HAdV-positive PCR.

RESULTS

Initial HAdV infection and disease definitions were developed and updated through an iterative process after reviewing clinical and virological details for 81 subjects with at least one positive HAdV PCR detected in a clinical specimen. Independent application of final definitions to 20 HAdV positive allo-HCT recipients by two CRCs yielded similar number of HAdV infection or disease events but with variation of degree of certainty for some events.

CONCLUSIONS

Application of definitions by a CRC for a study of HAdV infection and disease is feasible and can provide consistency in the assignment of outcomes. Definitions need further refinement to improve reproducibility and to provide guidance on determining clinical improvement or worsening after initial diagnosis of HAdV infection or disease.

Liver injury and prolonged hospitalization as indicators of severity in patients with adenovirus infections

BACKGROUND

Adenovirus (ADV) is a prevalent infective virus in children, accounting for around 5-10% of all cases of acute respiratory illnesses and 4-15% of pneumonia cases in children younger than five years old. Without treatment, severe ADV pneumonia could result in fatality rates of over 50% in cases of emerging strains or disseminated disease. This study aims to uncover the relationship of clinical indicators with primary ADV infection severity, regarding duration of hospitalization and liver injury.

METHODS

In this retrospective study, we collected and analyzed the medical records of 1151 in-patients who met the inclusion and exclusion criteria. According to duration of hospitalization, all patients were divided into three groups. Then the difference and correlation of clinical indicators with ADV infection were analyzed, and the relationship among liver injury, immune cells and cytokines was evaluated.

RESULTS

The study revealed that patients with a duration of hospitalization exceeding 14 days had the highest percentage of abnormalities across most indicators. This was in contrast to the patients with a hospitalization duration of either less than or equal to 7 days or between 7 and 14 days. Furthermore, correlation analysis indicated that a longer duration of body temperature of ≥ 39°C, bilateral lung lobes infiltration detected by X ray, abnormal levels of AST, PaO2, and SPO2, and a lower age were all predictive of longer hospital stays. Furthermore, an elevated AST level and reduced liver synthesis capacity were related with a longer hospital stay and higher ADV copy number. Additionally, AST/ALT was correlated positively with IFN-γ level and IFN-γ level was only correlated positively with CD4+ T cells.

CONCLUSIONS

The study provided a set of predicting indicators for longer duration of hospitalization, which responded for primary severe ADV infection, and elucidated the possible reason for prolonged duration of hospitalization attributing to liver injury via higher ADV copy number, IFN-γ and CD4+ T cells, which suggested the importance of IFN-γ level and liver function monitoring for the patients with primary severe ADV infection.

Clinical epidemiology of adenovirus pneumonia among Chinese hospitalized children

Adenovirus pneumonia is a prevalent form of community-acquired pneumonia among children. Research on the epidemiology and economic burden of this disease is crucial for public health, yet comprehensive data remains scarce, making it crucial to highlight on this topic. In this study, the data were extracted from the face sheet of discharge medical records collected from 26 tertiary children's hospitals from January 2016 to December 2021. In total, 1854 children with laboratory-confirmed adenovirus pneumonia were hospitalized, accounting for 0.13% of the total number of hospitalized for pneumonia in the database during the period. In addition, this figure represents a meager 0.027% when compared to the total number of hospitalized children. The male-to-female ratio was 1.78:1. The 1-3-year age group had the highest number of inpatients for adenoviral pneumonia and the largest proportion of the total hospitalizations in the same age group. Overall, winter is the primary season for the prevalence of adenovirus pneumonia, however, in southern China, there are two peak seasons, winter and summer. Although patients with 3/4 adenovirus pneumonia had no significant complications, some patients had complications such as respiratory failure, diarrhea, and myocardial damage. The median length of stay of adenovirus pneumonia was 8 d [interquartile range (IQR) 6-11], and the median hospitalization cost was 1293.83 United States dollars (IQR 811.81-2472.51). These valuable epidemiological insights into adenovirus pneumonia in Chinese children can help direct the development of targeted prevention and control strategies and surveillance measures for HAdV infections in this demographic.

Identification of a novel adenovirus in liver tissue sample of the Great Himalayan leaf-nosed bat (Hipposideros armiger)

Bats are important reservoirs for many zoonotic viruses. To explore and monitor potential novel viruses carried by bats, 21 liver samples of bats (Hipposideros armiger) were collected from Yunnan Province in southern China. Only one (4.8%) of all models was detected with adenovirus. The whole genome strain obtained by the viral metagenomics method combined with PCR was temporarily named YN01. The complete genome of YN01 was 37,676 bp, with a G + C content of 55.20% and 28 open reading frames. Phylogenetic analysis indicated that the strain YN01 can be classified as genus Mastadenovirus and was the most similar to the adenovirus isolated from Rhinolophus sinicus in China in 2016. The analysis is needed to verify the possibility of cross-species transmission. This virological investigation has increased our understanding of the ecology of bat-borne viruses in this area and provided a reference for possible future infectious diseases.

Risk factors and prediction models for bronchiolitis obliterans after severe adenoviral pneumonia

Severe adenoviral pneumonia (SAP) can cause post-infectious bronchiolitis obliterans (PIBO) in children. We aimed to investigate the relevant risk factors for PIBO and develop a predictive nomogram for PIBO in children with SAP. This prospective study analysed the clinical data of hospitalised children with SAP and categorised them into the PIBO and non-PIBO groups. Least absolute shrinkage and selection operator (LASSO) regressions were applied to variables that exhibited significant intergroup differences. Logistic regression was adopted to analyse the risk factors for PIBO. Additionally, a nomogram was constructed, and its effectiveness was assessed using calibration curves, C-index, and decision curve analysis. A total of 148 hospitalised children with SAP were collected in this study. Among them, 112 achieved favourable recovery, whereas 36 developed PIBO. Multivariable regression after variable selection via LASSO revealed that aged < 1 year (OR, 2.38, 95% CI, 0.82-6.77), admission to PICU (OR, 24.40, 95% CI, 7.16-105.00), long duration of fever (OR, 1.16, 95% CI, 1.04-1.31), and bilateral lung infection (OR, 8.78, 95% CI, 1.32-195.00) were major risk factors for PIBO. The nomogram model included the four risk factors: The C-index of the model was 0.85 (95% CI, 0.71-0.99), and the area under the curve was 0.85 (95% CI, 0.78-0.92). The model showed good calibration with the Hosmer-Lemeshow test (χ2 = 8.52, P = 0.38) and was useful in clinical settings with decision curve analysis.

CONCLUSION

Age < 1 year, PICU admission, long fever duration, and bilateral lung infection are independent risk factors for PIBO in children with SAP. The nomogram model may aid clinicians in the early diagnosis and intervention of PIBO.

WHAT IS KNOWN

• Adenoviruses are the most common pathogens associated with PIBO. • Wheezing, tachypnoea, hypoxemia, and mechanical ventilation are the risk factors for PIBO.

WHAT IS NEW

• Age < 1 year, admission to PICU, long duration of fever days, and bilateral lung infection are independent risk factors for PIBO in children with SAP. • A prediction model presented as a nomogram may help clinicians in the early diagnosis and intervention of PIBO.

Oral USC-093, a novel homoserinamide analogue of the tyrosinamide (S)-HPMPA prodrug USC-087 has decreased nephrotoxicity while maintaining antiviral efficacy against human adenovirus infection of Syrian hamsters

Adenovirus infections of immunocompromised humans are a significant source of morbidity and mortality. Presently, there is no drug specifically approved for the treatment of adenovirus infections by the FDA. The state-of-the-art treatment of such infections is the off-label use of cidofovir, an acyclic nucleotide phosphonate. While cidofovir inhibits adenovirus replication, it has dose-limiting kidney toxicity. There is an apparent need for a better compound to treat adenovirus infections. To this end, we have been developing acyclic nucleotide phosphonate prodrugs that utilize an amino acid scaffold equipped with a lipophilic modifier. Here, we compare the antiviral potential of two prodrugs of HPMPA that differ only in the amino acid-based promoiety: USC-087, based on an N-hexadecyl tyrosinamide, and USC-093, based on an N-hexadecyl serinamide. Oral administration of both compounds was very efficacious against disseminated HAdV-C6 infection in immunosuppressed Syrian hamsters, suppressing virus replication and mitigating pathology even when treatment was withheld until 4 days after challenge. We saw only marginal efficacy after respiratory infection of hamsters, which may reflect suboptimal distribution to the lung. Importantly, neither compound induced intestinal toxicity, which was observed as the major adverse effect in clinical trials of brincidofovir, a prodrug of cidofovir which also contains a C-16 modifier. Notably, we found that there was a significant difference in the nephrotoxicity of the two compounds: USC-087 caused significant kidney toxicity while USC-093 did not, at effective doses. These findings will be valuable guidepoints in the future evolution of this new class of potential prodrugs to treat adenovirus infections.

Adenovirus and Mycoplasma pneumoniae co-infection as a risk factor for severe community-acquired pneumonia in children

Background

To investigate the pathogenic characteristics and risk factors of pediatric severe community-acquired pneumonia (CAP).

Methods

We retrospectively analyzed the clinical data of hospitalized children with severe CAP from April 2014 to June 2019 in China. Data of age, sex and pathogenic results were collected: bacterial and fungal cultures, respiratory viruses from sputum or bronchoalveolar lavage fluid (BALF), serum Mycoplasma pneumoniae (MP)-IgM and Chlamydia Pneumoniae-IgM, and BALF or blood (1-3)-β-D-glucan/galactomannan test.

Results

A total of 679 children with severe CAP were included in the analysis. The number of cases infected with MP was higher in males than in females. There were significant differences between the ≤1-year and >1-year groups in terms of pathogen. The top three bacteria cultured were Haemophilus influenzae (57/679, 8.4%), Streptococcus pneumoniae (50/679, 7.4%), and Pseudomonas aeruginosa (25/679, 3.7%). The top three viruses detected were adenovirus (AdV, 124/679, 18.3%), respiratory syncytial virus (24/679, 3.5%), and parainfluenza virus (21/679, 3.1%). AdV and MP were the leading pathogens, detected in 18.3% and 32.6% cases, respectively. MP infection increased the risk of AdV infection (OR 3.77, p < 0.0001). MP infection was a risk factor for severe AdV-infected pneumonia, while sex, age, bacteria, Chlamydia Pneumoniae, fungal, and AdV infections were risk factors for severe MP-infected pneumonia.

Conclusions

AdV and MP were dominant pathogens in children with severe CAP. AdV and MP infection predisposed each other to develop severe illness. AdV-MP co-infection may lead to severe pneumonia.

A nationwide survey of adenovirus-associated encephalitis/encephalopathy in Japan

BACKGROUND

Adenovirus is a major pathogen causing febrile illness among children. It may also cause acute encephalitis/encephalopathy. This study aimed to elucidate the clinical features of adenovirus-associated encephalitis/encephalopathy (AdVE) among children in Japan.

METHODS

A nationwide survey of children with AdVE was conducted. An initial survey was distributed among pediatricians to obtain information about children with AdVE treated between January 2014 and March 2019. A second survey was used to obtain the clinical information of children with AdVE from hospitals that responded to the initial survey and those identified from a literature search of the reported cases. We collected demographic data and information about symptoms of infection, neurological symptoms, laboratory parameters, treatment, and outcomes. Outcomes were determined using the Pediatric Cerebral Performance Category Score.

RESULTS

Clinical information was available for 23 children with a median age of 39 months. Two had preexisting neurological disorders and six had a history of febrile seizures. The outcome was good in 15 patients and poor in eight patients. Serum lactate dehydrogenase, glucose, and ammonia levels were higher among children with a poor outcome compared to those with a good outcome. Clinically mild encephalitis/encephalopathy with a reversible splenial lesion was the most common type (n = 8), followed by acute encephalopathy with biphasic seizures and late reduced diffusion (n = 7).

CONCLUSION

A prior history of febrile seizures was frequent in children with AdVE. Several different subtypes of acute encephalopathy were seen in children with AdVE, and the outcome was poor in those with acute encephalopathy with biphasic seizures and late reduced diffusion and hemorrhagic shock and encephalopathy syndrome. Elevated lactate dehydrogenase, glucose, and ammonia levels on admission were found to correlate with a poor outcome.

Construction and application of adenoviral vectors

Adenoviral vectors have been widely used as vaccine candidates or potential vaccine candidates against infectious diseases due to the convenience of genome manipulation, their ability to accommodate large exogenous gene fragments, easy access of obtaining high-titer of virus, and high efficiency of transduction. At the same time, adenoviral vectors have also been used extensively in clinical research for cancer gene therapy and treatment of diseases caused by a single gene defect. However, application of adenovirus also faces a series of challenges such as poor targeting, strong immune response against the vector itself, and they cannot be used repeatedly. It is believed that these problems will be solved gradually with further research and technological development in related fields. Here, we review the construction methods of adenoviral vectors, including "gutless" adenovirus and discuss application of adenoviral vectors as prophylactic vaccines for infectious pathogens and their application prospects as therapeutic vaccines for cancer and other kinds of chronic infectious disease such as human papillomavirus, hepatitis B virus, and hepatitis C virus.

Pathogenicity and virulence of human adenovirus F41: Possible links to severe hepatitis in children

Over 100 human adenoviruses (HAdVs) have been isolated and allocated to seven species, A-G. Species F comprises two members-HAdV-F40 and HAdV-F41. As their primary site of infection is the gastrointestinal tract they have been termed, with species A, enteric adenoviruses. HAdV-F40 and HAdV-F41 are a common cause of gastroenteritis and diarrhoea in children. Partly because of difficulties in propagating the viruses in the laboratory, due to their restrictions on growth in many cell lines, our knowledge of the properties of individual viral proteins is limited. However, the structure of HAdV-F41 has recently been determined by cryo-electron microscopy. The overall structure is similar to those of HAdV-C5 and HAdV-D26 although with some differences. The sequence and arrangement of the hexon hypervariable region 1 (HVR1) and the arrangement of the C-terminal region of protein IX differ. Variations in the penton base and hexon HVR1 may play a role in facilitating infection of intestinal cells by HAdV-F41. A unique feature of HAdV-F40 and F41, among human adenoviruses, is the presence and expression of two fibre genes, giving long and short fibre proteins. This may also contribute to the tropism of these viruses. HAdV-F41 has been linked to a recent outbreak of severe acute hepatitis "of unknown origin" in young children. Further investigation has shown a very high prevalence of adeno-associated virus-2 in the liver and/or plasma of some cohorts of patients. These observations have proved controversial as HAdV-F41 had not been reported to infect the liver and AAV-2 has generally been considered harmless.

Genome and proteomic analysis of risk factors for fatal outcome in children with severe community-acquired pneumonia caused by human adenovirus 7

INTRODUCTION

Human adenovirus 7 (HAdV-7) is an important viral pathogen of severe pneumonia in children and a serious threat to health.

METHODS

A cohort of 45 pediatric patients diagnosed with HAdV-7-associated severe pneumonia and admitted to the Pediatric Intensive Care Unit at the Children's Hospital of Chongqing Medical University from May 2018 to January 2020 were included. Risk factors of death were analyzed by the Cox proportional risk mode with Clinical data, serum, and nasopharyngeal aspirate adenovirus load, Genome analysis, Olink proteomics, and cytokine profile between dead and surviving patients were also analyzed.

RESULTS

A total of 45 children with a median age of 12.0 months (interquartile range [IQR]: 6.5, 22.0) were included (female 14), including 14 (31.1%) who died. High serum viral load was an independent risk factor for mortality (hazard ratio [HR] = 2.16, 95% confidence interval [CI], 1.04-4.49, p = 0.039). BTB and CNC homology 1 (BACH1), interleukin-5 (IL-5), and IL-9 levels were significantly correlated with serum viral load (p = 0.0400, 0.0499, and 0.0290; r = 0.4663, 0.3339, and -0.3700, respectively), with significant differences between the dead and survival groups (p = 0.021, 0.001, and 0.021).

CONCLUSIONS

Severe cytokine storm-associated high serum viral load after HAdV-7 infection may be the main mechanism responsible for poor prognosis in children.

Molecular characterization of human adenovirus causing infantile acute gastroenteritis in Venezuela before and after rotavirus vaccine implementation

Human adenoviruses (HAdV) of species F are commonly involved in pediatric acute gastroenteritis (AGE). The real impact on Venezuelan health is unknown. To investigate the prevalence and molecular diversity of HAdV in Venezuela, 630 fecal samples collected from children with AGE in 3 cities, from 2001 to 2013, were tested by PCR. Species F and types F40/41 were identified by REA. HAdV was detected in 123 cases (19.5%), most from outpatient females under 24 months old. A progressive and substantial increase in the detection rate was observed over time, significantly higher in rotavirus vaccinated than unvaccinated children (28.4% vs. 9.5%, P = 0.00019). Phylogenetic analysis of 28 randomly selected genomes showed high similarity among HAdV-F40/41 and those worldwide. HAdV-F of type 41 prevailed (79.8%) and clustered into 2 intratypic major clades. The significant involvement of HAdV-F41 in AGE suggests the importance of actively monitoring viral agents other than rotavirus, especially after vaccine introduction.

Clinical Characteristics and Genotyping of Pediatric Adenovirus Pneumonia Disease and Coinfection in Southeast China

Introduction: Human adenovirus (HAdV) is a common pathogen that can cause acute respiratory infections (ARIs) in children. Adenovirus pneumonia is the most severe respiratory disease associated with HAdV. Objective: We aimed to investigate the clinical characteristics of children hospitalized with adenovirus pneumonia in Quanzhou, China, in 2019. We also sought to determine the viral genotype in these cases and explore cases associated with severe adenovirus pneumonia. Methods: We collected oropharyngeal swabs from 99 children who were hospitalized with pneumonia in Quanzhou Women and Children's Hospital, these samples were tested for the presence of HAdV. Genotyping of the viruses was performed by real-time polymerase chain reaction. Logistic regression analysis was employed to analyze risk factors related to severe adenovirus pneumonia. The epidemiological data were examined using the Statistical Package for Social Sciences software (SPSS). Results: Among the 99 patients in our study, the median age was 21 months. We observed a 4% mortality rate among those diagnosed with adenovirus pneumonia. Adenovirus pneumonia often presents as a coinfection. Lactate dehydrogenase and neutrophil percentages of WBC's were significantly increased in patients with severe adenovirus pneumonia compared with mild HAdV disease. The predominant viral genotypes identified were type 3 and type 7. Conclusions: In the Quanzhou area of southeast China, the incidence of adenovirus pneumonia was found to be high among children younger than two years old. Type 7 HAdV was identified as the primary pathogen. A long duration of fever, dyspnea and digestive system complications were risk factors for severe adenovirus pneumonia after HAdV infection. Clinical Trial Registration number: ChiCTR2200062358.

Molecular epidemiology and phylogenetic analyses of human adenovirus in pediatric patients with acute respiratory infections from Hangzhou during COVID-19 pandemic

Background

Acute Respiratory Infections (ARIs) are a major cause of morbidity and mortality worldwide. Human Adenovirus (HAdV), responsible for 5%-10% of children's ARIs, is one of the most prevalent pathogens. Our study aimed to analyze the epidemiology and phylogenesis of HAdV in pediatric patients with ARIs in Hangzhou during the COVID-19 pandemic.

Method

Between November 2020 and March 2021, we collected 1,442 nasopharyngeal swabs from children with ARIs at Children's Hospital, Zhejiang University School of Medicine. Epidemiological statistics, phylogenetic and amino acid (AA) mutation analysis were conducted.

Results

Our findings revealed that 386 (26.77%) samples tested positive for HAdV, with the highest rate in children aged 6-18 years and the lowest in children aged 0-1 year, indicating a different age preference of HAdV compared with pre-pandemic period. Outpatients had a significantly higher positive rate than inpatients. Moreover, patients with HAdV-coinfection exhibited more severe clinical symptoms than those with HAdV-single infection. Our phylogenetic analysis demonstrated that species HAdV-C (type 1, 2, 6) were the predominant circulating strains in Hangzhou during the COVID-19 pandemic. Further AA mutation analysis identified seventeen mutations of particular concern for biological characterization.

Conclusion

In conclusion, our study provides valuable epidemiological and molecular data that will aid in epidemiological surveillance, antiviral therapies and the development of specific vaccine types, leading to improve public health.

Dissemination and genome characterization of a human adenovirus F41 in a patient with B-Cell lymphoma

Adenovirus (HAdV) F41 is a common cause of gastroenteritis and has rarely been reported associated with disseminated disease. In this report, an adult patient with a history of ulcerative colitis, cryptogenic cirrhosis, stage III adenocarcinoma, high-grade diffuse large B-cell lymphoma on chemotherapy was diagnosed with disseminated adenovirus infection. HAdV DNA was quantified in stool, plasma, and urine with viral loads of 7, 4, and 3 log10 copies/mL, respectively. The patient's course was rapidly progressive and he passed away 2 days after initiation of antiviral therapy. The patient's infecting virus was characterized as HAdV-F41 by whole genome sequencing.

Pediatric adenovirus pneumonia: clinical practice and current treatment

Adenovirus pneumonia is common in pediatric upper respiratory tract infection, which is comparatively easy to develop into severe cases and has a high mortality rate with many influential sequelae. As for pathogenesis, adenoviruses can directly damage target cells and activate the immune response to varying degrees. Early clinical recognition depends on patients' symptoms and laboratory tests, including those under 2 years old, dyspnea with systemic toxic symptoms, atelectasis or emphysema in CT image, decreased leukocytes, and significantly increased C-reaction protein (CRP) and procalcitonin (PCT), indicating the possibility of severe cases. Until now, there is no specific drug for adenovirus pneumonia, so in clinical practice, current treatment comprises antiviral drugs, respiratory support and bronchoscopy, immunomodulatory therapy, and blood purification. Additionally, post-infectious bronchiolitis obliterans (PIBO), hemophagocytic syndrome, and death should be carefully noted. Independent risk factors associated with the development of PIBO are invasive mechanical ventilation, intravenous steroid use, duration of fever, and male gender. Meanwhile, hypoxemia, hypercapnia, invasive mechanical ventilation, and low serum albumin levels are related to death. Among these, viral load and serological identification are not only "gold standard" for adenovirus pneumonia, but are also related to the severity and prognosis. Here, we discuss the progress of pathogenesis, early recognition, therapy, and risk factors for poor outcomes regarding severe pediatric adenovirus pneumonia.

Gastrointestinal tract and viral pathogens

Viral gastroenteritis is the most common viral illness that affects the gastrointestinal (GI) tract, causing inflammation and irritation of the lining of the stomach and intestines. Common signs and symptoms associated with this condition include abdominal pain, diarrhea, and dehydration. The infections commonly involved in viral gastroenteritis are rotavirus, norovirus, and adenovirus, which spread through the fecal-oral and contact routes and cause non-bloody diarrhea. These infections can affect both immunocompetent and immunocompromised individuals. Since the pandemic in 2019, coronavirus gastroenteritis has increased in incidence and prevalence. Morbidity and mortality rates from viral gastroenteritis have declined significantly over the years due to early recognition, treatment with oral rehydration salts, and prompt vaccination. Improved sanitation measures have also played a key role in reducing the transmission of infection. In addition to viral hepatitis causing liver disease, herpes virus, and cytomegalovirus are responsible for ulcerative GI disease. They are associated with bloody diarrhea and commonly occur in im-munocompromised individuals. Hepatitis viruses, Epstein-Barr virus, herpesvirus 8, and human papillomavirus have been involved in benign and malignant diseases. This mini review aims to list different viruses affecting the GI tract. It will cover common symptoms aiding in diagnosis and various important aspects of each viral infection that can aid diagnosis and management. This will help primary care physicians and hospitalists diagnose and treat patients more easily.

Generation and Characterization of a Replication-Competent Human Adenovirus Type 55 Encoding EGFP

Human adenovirus 55 (HAdV-55) has recently caused outbreaks of acute respiratory disease (ARD), posing a significant public threat to civilians and military trainees. Efforts to develop antiviral inhibitors and quantify neutralizing antibodies require an experimental system to rapidly monitor viral infections, which can be achieved through the use of a plasmid that can produce an infectious virus. Here, we used a bacteria-mediated recombination approach to construct a full-length infectious cDNA clone, pAd55-FL, containing the whole genome of HadV-55. Then, the green fluorescent protein expression cassette was assembled into pAd55-FL to replace the E3 region to obtain a recombinant plasmid of pAd55-dE3-EGFP. The rescued recombinant virus rAdv55-dE3-EGFP is genetically stable and replicates similarly to the wild-type virus in cell culture. The virus rAdv55-dE3-EGFP can be used to quantify neutralizing antibody activity in sera samples, producing results in concordance with the cytopathic effect (CPE)-based microneutralization assay. Using an rAdv55-dE3-EGFP infection of A549 cells, we showed that the assay could be used for antiviral screening. Our findings suggest that the rAdv55-dE3-EGFP-based high-throughput assay provides a reliable tool for rapid neutralization testing and antiviral screening for HAdV-55.

Viral Pneumonia during the COVID-19 Pandemic, 2019-2021 Evoking Needs for SARS-CoV-2 and Additional Vaccinations

Coronaviruses can cause pneumonia, with clinical symptoms that may be similar to the symptoms of other viral pneumonias. To our knowledge, there have been no reports regarding cases of pneumonia caused by coronaviruses and other viruses among hospitalized patients in the past 3 years before and during coronavirus disease 2019 (COVID-19). Here, we analysed the causes of viral pneumonia among hospitalized patients during the coronavirus disease 2019 (COVID-19) pandemic (2019-2021). Between September 2019 and April 2021, patients hospitalized at Shuang Ho Hospital in north Taiwan with a diagnosis of pneumonia were enrolled in this study. Age, sex, onset date, and season of occurrence were recorded. Respiratory tract pathogens were identified with molecular detection using the FilmArray^® platform from nasopharyngeal swabs. In total, 1147 patients (128 patients aged <18 years and 1019 patients aged ≥18 years) with pneumonia and identified respiratory tract pathogens were assessed. Among the 128 children with pneumonia, the dominant viral respiratory pathogen was rhinovirus (24.2%), followed by respiratory syncytial virus (RSV; 22.7%), parainfluenza virus (1 + 2 + 3 + 4) (17.2%), adenovirus (12.5%), metapneumovirus (9.4%), coronavirus (1.6%), and influenza virus (A + B) (1.6%). Among the 1019 adults with pneumonia, the dominant viral respiratory pathogen was rhinovirus (5.0%), followed by RSV (2.0%), coronavirus (2.0%), metapneumovirus (1.5%), parainfluenza virus (1 + 2 + 3 + 4) (1.1%), adenovirus (0.7%), and influenza virus (A + B) (0%). From 2019-2021, older patients (aged >65 years) with pneumonia tested positive for coronavirus most commonly in autumn. Coronavirus was not detected during summer in children or adults. Among children aged 0-6 years, RSV was the most common viral pathogen, and RSV infection occurred most often in autumn. Metapneumovirus infection occurred most often in spring in both children and adults. In contrast, influenza virus was not detected in patients with pneumonia in any season among children or adults from January 2020 to April 2021. Among all patients with pneumonia, the most common viral pathogens were rhinovirus in spring, adenovirus and rhinovirus in summer, RSV and rhinovirus in autumn, and parainfluenza virus in winter. Among children aged 0-6 years, RSV, rhinovirus, and adenovirus were detected in all seasons during the study period. In conclusion, the proportion of pneumonia cases caused by a viral pathogen was higher in children than the proportion in adults. The COVID-19 pandemic period evoked a need for SARS-CoV-2 (severe acute respiratory disease coronavirus 2) vaccination to prevent the severe complications of COVID-19. However, other viruses were also found. Vaccines for influenza were clinically applied. Active vaccines for other viral pathogens such as RSV, rhinovirus, metapneuomoccus, parainfluenza, and adenovirus may need to be developed for special groups in the future.

Immunogenicity Differences of the ChAdOx1 nCoV-19 Vaccine According to Pre-Existing Adenovirus Immunity

This study investigated the immunogenicity of, and reactogenicity to, the ChAdOx1 nCoV-19 vaccine according to pre-existing adenovirus immunity. Individuals scheduled for COVID-19 vaccination were prospectively enrolled in a tertiary hospital with 2400 beds from March 2020 onwards. Pre-existing adenovirus immunity data was obtained before ChAdOx1 nCoV-19 vaccination. A total of 68 adult patients administered two doses of the ChAdOx1 nCoV-19 vaccine were enrolled. Pre-existing adenovirus immunity was identified in 49 patients (72.1%), but not in the remaining 19 patients (27.9%). The geometric mean titer of S-specific IgG antibodies was statistically higher in individuals without pre-existing adenovirus immunity at several time points: before the second ChAdOx1 nCoV-19 dose (56.4 (36.6–125.0) vs. 51.0 (17.9–122.3), p = 0.024), 2–3 weeks after the second ChAdOx1 nCoV-19 dose (629.5 (451.5–926.5) vs. 555.0 (287.3–926.0), p = 0.049), and 3 months after the second ChAdOx1 nCoV-19 dose (274.5 (160.5–655.3) vs. 176.0 (94.3–255.3), p = 0.033). In the absence of pre-existing adenovirus immunity, systemic events were observed with higher frequency, especially chills (73.7% vs. 31.9%, p = 0.002). In conclusion, individuals without pre-existing adenovirus immunity showed a higher immune response to ChAdOx1 nCoV-19 vaccination and a higher frequency of reactogenicity to ChAdOx1 nCoV-19 vaccination was observed.

Emerging viral infections in immunocompromised patients: A great challenge to better define the role of immune response

The immune response to invading pathogens is characterized by the rapid establishment of a complex network of cellular interactions and soluble signals. The correct balancing of activating and regulating pathways and tissue-homing signals determines its effectiveness and persistence over time. Emerging viral pathogens have always represented a great challenge to the immune system and an often uncontrolled/imbalanced immune response has been described (e.g. cytokine storm, immune paralysis), contributing to the severity of the disease. Several immune biomarkers and cell subsets have been identified as major players in the cascade of events leading to severe diseases, highlighting the rationale for host-directed intervention strategy. There are millions of immunocompromised pediatric and adult patients worldwide (e.g. transplant recipients, hematologic patients, subjects with primary immune-deficiencies), experiencing an impaired immune reactivity, due to diseases and/or to the medical treatments. The reduced immune reactivity could have two paradoxical non-exclusive effects: a weak protective immunity on one hand, and a reduced contribution to immune-mediated pathogenetic processes on the other hand. In these sensitive contexts, the impact of emerging infections represents a still open issue to be explored with several challenges for immunologists, virologists, physicians and epidemiologists. In this review, we will address emerging infections in immunocompromised hosts, to summarize the available data concerning the immune response profile, its influence on the clinical presentation, the possible contribution of persistent viral shedding in generating new viral variants with improved immune escape features, and the key role of vaccination.

Clustered cases of human adenovirus types 4, 7, and 14 infections in US Department of Defense Beneficiaries during the 2018-2019 season

Human adenoviruses (HAdV) are genetically diverse and can infect a number of tissues with severities varied from mild to fatal. HAdV types 3, 4, 7, 11, 14, 21, and 55 were associated with acute respiratory illnesses outbreaks in the United States and in other countries. The risk of outbreaks can be effectively controlled by HAdV vaccination or mitigated by screening and preventive measures. During the influenza season 2018-2019, the DoD Global Respiratory Pathogen Surveillance Program (DoDGRS) received 24 300 respiratory specimens. HAdV samples that produced positive cytopathic effects in viral cultivation were subjected to next-generation sequencing for genome sequence assembly, genome typing, whole genome phylogeny, and sequence comparative analyses. A variety of HAdV types were identified in this study, including HAdV types 1-7, 14, 55, and 56. HAdV types 4, 7, and 14 were found in clustered cases in Colorado, Florida, New York, and South Carolina. Comparative sequence analyses of these isolates revealed the emergence of novel genetic mutations despite the stability of adenovirus genomes. Genomic surveillance of HAdV suggested possible undetected outbreaks and shed light on prevalence, genetic divergence, and viral evolution of HAdV. Continued surveillance will inform risk assessment and countermeasures.

Adenoviruses in medicine: innocuous pathogen, predator, or partner

The consequences of human adenovirus (HAdV) infections are generally mild. However, despite the perception that HAdVs are harmless, infections can cause severe disease in certain individuals, including newborns, the immunocompromised, and those with pre-existing conditions, including respiratory or cardiac disease. In addition, HAdV outbreaks remain relatively common events and the recent emergence of more pathogenic genomic variants of various genotypes has been well documented. Coupled with evidence of zoonotic transmission, interspecies recombination, and the lack of approved AdV antivirals or widely available vaccines, HAdVs remain a threat to public health. At the same time, the detailed understanding of AdV biology garnered over nearly 7 decades of study has made this group of viruses a molecular workhorse for vaccine and gene therapy applications.

Comparison of clinical, laboratory and radiological characteristics between Chlamydia psittaci and adenovirus pneumonias: a multicenter retrospective study

OBJECTIVES

Pneumonia caused by Chlamydia psittaci is a significant global public health issue. Symptom onset and laboratory characteristics may be confused with those of other respiratory viral infections, including adenovirus pneumonia. We aimed to determine differences in clinical presentations and establish a simple nomogram to differentiate C. psittaci and adenovirus pneumonias.

METHODS

We conducted a multicenter retrospective study in 10 tertiary general hospitals to compare patients with either C. psittaci (n = 78) or adenovirus (n = 102) pneumonia. A multivariable logistic regression model was used to identify risk factors of C. psittaci pneumonia that were used to establish a nomogram.

RESULTS

C. psittaci and adenovirus pneumonia showed certain similar clinical symptoms, including fever, dyspnea, and fatigue, but differed in other characteristics. The multivariate logistic regression showed that age, sex, nervous system symptoms, lymphocyte count, C-reactive protein level, and bilateral lung lesions were risk factors for C. psittaci pneumonia. After incorporating these six factors, the established nomogram achieved a good concordance value (0.949 [95% CI 0.917-0.982]) in differentiating the types of pneumonia, with well-fitting calibration curves.

CONCLUSION

Despite having similar clinical features, the variables of age, sex, nervous system symptoms, lymphocytes, C-reactive protein levels, and bilateral lung lesions were combined into a clinically useful nomogram for the rapid and early differentiation of C. psittaci pneumonia from adenovirus pneumonia. This nomogram may help improve treatments and clinical outcomes.

[(Rare) infectious hepatitis as an important differential diagnosis of unclear hepatopathy]

BACKGROUND

Liver biopsies to determine the cause of unclear hepatopathy and acute liver failure represent a diagnostic hallmark and require close cooperation between clinicians and pathologists. The commonly acute presentation of hepatic dysfunction warrants a rapid diagnosis. Infectious causes of hepatitis may be identified by the pathologist, supporting further diagnostic and therapeutic steps.

OBJECTIVES

Rare infectious causes of hepatic dysfunction with distinct histomorphological features are presented.

MATERIALS AND METHODS

Retrospective cases of liver biopsies for evaluation of hepatic dysfunction with infection confirmed by laboratory tests were selected from the archive of the institute of pathology of TUM and evaluated for morphologic diagnostic criteria.

RESULTS AND CONCLUSIONS

Infections with adenovirus, Herpes simplex virus, Hepatitis A virus, and coxiella burnettii are rare findings in liver core biopsies but able to cause hepatic dysfunction that present with distinct histomorphologic alterations that can contribute to the identification of the causative agent. Rare infectious causes should be considered in any patient presenting with hepatic dysfunction of unknown etiology. Knowledge of the histomorphologic criteria by the pathologist is crucial to initiate further diagnostic testing and treatment.

Acute severe hepatitis outbreak in children: A perfect storm. What do we know, and what questions remain?

During the first half of 2022, the World Health Organization reported an outbreak of acute severe hepatitis of unknown aetiology (AS-Hep-UA) in children, following initial alerts from the United Kingdom (UK) where a cluster of cases was first observed in previously well children aged <6 years. Sporadic cases were then reported across Europe and worldwide, although in most countries incidence did not increase above the expected baseline. There were no consistent epidemiological links between cases, and microbiological investigations ruled out known infectious causes of hepatitis. In this review, we explore the evidence for the role of viral infection, superimposed on a specific host genetic background, as a trigger for liver pathology. This hypothesis is based on a high prevalence of Human Adenovirus (HAdV) 41F in affected children, together with metagenomic evidence of adeno-associated virus (Adeno-associated viruses)-2, which is a putative trigger for an immune-mediated liver injury. Roles for superantigen-mediated pathology have also been explored, with a focus on the potential contribution of SARS-CoV-2 infection. Affected children also had a high frequency of the MHC allele HLA-DRB1*04:01, supporting an immunological predisposition, and may have been vulnerable to viral coinfections due to disruption in normal patterns of exposure and immunity as a result of population lockdowns during the COVID-19 pandemic. We discuss areas of ongoing uncertainty, and highlight the need for ongoing scrutiny to inform clinical and public health interventions for this outbreak and for others that may evolve in future.

Severe acute hepatitis in children with unknown aetiology, etiology analysis and the next action

•MIS-C and severe acute hepatitis might share the common pathogenic mechanism. •SARS-CoV-2 persistence throughout multiorgan and tissues. •Relationship between COVID-19 vaccines and severe acute hepatitis worth investigating.

Change on the Circulation of Respiratory Viruses and Pediatric Healthcare Utilization during the COVID-19 Pandemic in Asturias, Northern Spain

(1) Background: The COVID-19 pandemic and the implementation of restrictions and nonpharmaceutical interventions (NPIs) changed the trends in respiratory viral circulation and the pattern in pediatric healthcare utilization; (2) Methods: A retrospective, multicenter observational study designed to analyze the impact of the pandemic on pediatric healthcare utilization and the viral circulation pattern in children in a region in Northern Spain was carried out. Viral diagnostics data from all nasal or pharyngeal swabs collected in children in Asturias during the periods of March 2018−September 2019 and March 2020−September 2021 were analyzed, as well as the number of pediatric hospitalizations and emergency visits; (3) Results: A total of 14,640 samples were collected during the pandemic period. Of these, at least one respiratory virus was detected in 2940 (20.1%) while 5568/10,298 samples were positive in the pre-pandemic period (54.1%); p < 0.001. The detection of both enveloped and non-enveloped viruses decreased among periods (p < 0.001). After week 14, 2020, enveloped viruses were no longer detected until one year later, while non-enveloped viruses continued to be detected in children. Overall, a mean of 4946.8 (95% CI 4519.1−5374.4) pediatric emergency visits per month during the period 2018−2019 as compared to 2496.5 (95% CI 2086.4−2906.5) for 2020−2021 occurred (p < 0.001). The mean of pediatric hospitalizations also significantly decreased between periods, as follows: 346.6 (95% CI 313−380.2) in 2018−2019 vs. 161.1 (95% CI 138.4−183.8); p < 0.001; (4) Conclusions: Our study showed a remarkably reduction in pediatric hospitalizations and emergency visits and a change in the pattern of viral circulation during the COVID-19 pandemic in Asturias. The usual seasonal respiratory viruses, namely influenza or RSV were nearly absent in the pediatric population during the pandemic.

Acute hepatitis of unknown origin in Europe—Adding fuel to already burning pandemic

The rise in the cases of acute hepatitis of unknown aetiology in the paediatric population is a public health concern worldwide and investigations to ascertain the exact cause of this outbreak are being carried out extensively by the concerned authorities. In early April 2022, the World Health Organisation (WHO) issued a warning on acute hepatitis of unknown origin in children. Since then, there have been continuing additional reports of the cases globally. The recent cases of acute hepatitis of unknown aetiology are more prevalent in children aged <10 years, are more clinically severe, and a high percentage of infected individuals develop acute liver failure in contrast to the previous cases. The aetiology of this disease and its complete pathogenesis is still unclear. This review critically focuses on the current leading hypothesis and provides comprehensive information regarding this recent outbreak that can help in handling the situation by a better understanding of its aetiology.

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Various cases of acute hepatitis of unknown origin have been reported to WHO from different countries.

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Most of the cases reported were of the children from one month to 16 years and majority of them were infected with adenovirus.

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The diseases is challenging due to its unknown aetiology, insufficient data to establish management plans and its severity.

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International health organizations have teamed up and set up surveillance systems and investigations to help identify the aetiology.

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WHO and CDC have recommended general preventive measures including hand and respiratory hygiene.

Severe acute hepatitis of unknown aetiology in children-what is known?

The ongoing investigations into clusters of children affected by severe acute hepatitis of unknown aetiology have put our global capacity for a coordinated, effective response to the test. The global health community have rapidly convened to share data and inform the response. In the UK, where most cases were initially identified, a coordinated public health and clinical research response was rapidly initiated. Since then, cases have been reported from other countries, predominantly from higher-income countries. While agencies are keeping an open mind to the cause, the working hypothesis and case notifications raise important questions about our capacity to detect emerging cases in lower-resourced settings with a recognised lack of access to diagnostics even for commonly circulating viruses such as hepatitis A. The limited capability to generate integrated global pathogen surveillance data is a challenge for the outbreak investigations, highlighting an urgent need to strengthen access to diagnostics, with a focus on lower-resourced settings, to improve the capacity to detect emerging diseases to inform care and to improve outcomes and outbreak control.

Soluble Receptor for Advanced Glycation End Product Is Involved in the Inflammatory Response of Human Adenovirus-Infected Patients

Human adenovirus (HAdV) infection causes excessive inflammation associated with severe tissue injury, such as pneumonia. The molecules involved in the underlying inflammatory mechanisms remain to be elucidated. Receptor for advanced glycation end product (RAGE) is mainly expressed on immune cells and lung tissues, and it is a key factor in the initiation and development of inflammation. RAGE can be cleaved by metalloprotease 9 (MMP9) to release the extracellular segment, which is named soluble RAGE (sRAGE), into the intercellular space, where it can bind to RAGE ligands and block RAGE activation and subsequent inflammation. In our study, we enrolled HAdV-infected patients and their contacts to examine the relationship between sRAGE and inflammation induced by HAdV infection. The results showed that HAdV infection stimulated inflammatory cytokine secretion, increased such as high mobility group box 1 (HMGB1) levels, and suppressed sRAGE expression. sRAGE levels were significantly different between patients with or without pneumonia. We also found that MMP9 was significantly lower in patients with pneumonia, and it was positively correlated with sRAGE levels over 7 days after disease onset. The mitogen-activated protein kinase (MAPK) pathway is an important immune activation signaling pathway that is regulated by RAGE. We observed the activation of the MAPK pathway in the peripheral blood mononuclear cells (PBMCs) of patients. Negative correlations between sRAGE and phosphorylated JNK and p38 were observed. These results suggest that sRAGE is involved in HAdV-induced inflammatory responses, and might be a potential therapeutic target to alleviate the HAdV-induced excessive inflammation.

Acute, Severe Hepatitis of Unknown Origin: Should We Really Be Afraid of Another Obscure Enemy of Our Children?

On 31 March 2022, Public Health Scotland was alerted to five children aged 3-5 years, presenting to the Glasgow children's hospital with severe hepatitis of unknown etiology within a 3-week period [...].

Study on the Anti-Adenovirus Mechanism of Sargassum fusiforme

Human adenovirus (HAdV) has a worldwide distribution and remains a major pathogen that leads to infections of the respiratory tract. No specific treatments or vaccines are yet available for HAdV infection. Sargassum fusiforme, an edible seaweed, has attracted a lot of attention for its various bioactivities. S. fusiforme has been reported to exhibit antiviral activity. However, research studies about its anti-HAdV activity are few. In this research, we found that S. fusiforme had low cytotoxicity and possessed anti-human adenovirus type 7 (HAdV7) activity in vitro, and the most effective ingredient was alginate. The time of addition assay demonstrated inhibitory effects that were observed in all life stages of the virus. In addition, we observed that the antiviral activity of alginate against HAdV7 infection might be closely related to the endoplasmic reticulum stress (ERS) pathway. Taken together, these results suggest that S. fusiforme extracts have potential application in the prevention and treatment of HAdV infection.