Clinical Features, Replication Competence, and Innate Immune Responses of Human Adenovirus Type 7 Infection

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.

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.

Higher affinities of fibers with cell receptors increase the infection capacity and virulence of human adenovirus type 7 and type 55 compared to type 3

IMPORTANCE

HAdV-3, -7, and -55 are the predominant types causing acute respiratory disease outbreaks and can lead to severe and fatal pneumonia in children and adults. In recent years, emerging or re-emerging strains of HAdV-7 and HAdV-55 have caused multiple outbreaks globally in both civilian and military populations, drawing increased attention. Clinical studies have reported that HAdV-7 and HAdV-55 cause more severe pneumonia than HAdV-3. This study aimed to investigate the mechanisms explaining the higher severity of HAdV-7 and HAdV-55 infection compared to HAdV-3 infection. Our findings provided evidence linking the receptor-binding protein fiber to stronger infectivity of the strains mentioned above by comparing several fiber-chimeric or fiber-replaced adenoviruses. Our study improves our understanding of adenovirus infection and highlights potential implications, including in novel vector and vaccine development.

Comparative analysis of the impact of 40 adenovirus types on dendritic cell activation and CD8+ T cell proliferation capacity for the identification of favorable immunization vector candidates

For the development of new adenovirus (AdV)-based vectors, it is important to understand differences in immunogenicity. In a side-by-side in vitro analysis, we evaluated the effect of 40 AdV types covering human AdV (HAdV) species A through G on the expression of 11 activation markers and the secretion of 12 cytokines by AdV-transduced dendritic cells, and the effect on CD8+ T cell proliferation capacity. We found that the expression of activation markers and cytokines differed widely between the different HAdV types, and many types were able to significantly impair the proliferation capacity of CD8+ T cells. Univariate and multivariate regression analyses suggested an important role of type I interferons in mediating this suppression of CD8+ T cells, which we confirmed experimentally in a proliferation assay using a type I interferon receptor blocking antibody. Using Bayesian statistics, we calculated a prediction model that suggests HAdV types HAdV-C1, -D8, -B7, -F41, -D33, -C2, -A31, -B3 and -D65 as the most favorable candidates for vaccine vector development.

Abnormal liver function in children hospitalized with acute respiratory infection of adenoviruses: a retrospective study

Human adenoviruses (HAdVs) can cause acute hepatitis in immunocompromised patients. However, it is unclear whether HAdVs are contributors to hepatitis in immunocompetent children. In this study, the liver function test (LFT) results were retrospectively analyzed among children hospitalized (age <14 years) between January 2016 and October 2019 for acute respiratory infection caused by adenoviruses. Alanine transaminase (ALT) and aspartate aminotransferase (AST) levels were elevated in 7.74% and 46.89% of patients, respectively. All patients with >2 folds of the upper limit of ALT or AST levels were infected with HAdV-7 or HAdV-55. Significantly higher levels of ALT, AST, γ-glutamyl transpeptidase (γ-GT), and lower albumin levels were observed in the HAdV-7 infection group than in the HAdV-3 infection group. HAdV-55 infection led to significantly higher γ-GT, total bilirubin, and direct bilirubin levels than the other infection types. The records of four patients with serial monitoring of the LFT results were further analyzed. Multiple indicators remained abnormal during the entire hospitalization in these patients. These results indicate that HAdV infection is often accompanied by abnormal liver function, and HAdV-7 and HAdV-55 might be under-recognized contributors to hepatitis among children.

Computational insights into pediatric adenovirus inhibitors: in silico strategies for drug repurposing

Human adenovirus (HADV) infection can pose a serious threat to children, leading to a variety of respiratory illnesses and other complications. Particularly, children with weak immune systems are vulnerable to severe adenovirus infections with high mortality. The main focus of this study is to propose new antiviral agents as lead HADV inhibitors for children. So, several antiviral agents used in children were subjected to finding new HADV inhibitors using important computational methods of molecular docking, molecular dynamics (MD) simulation, Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) binding free energy calculations, density functional theory (DFT), and pharmacokinetic analysis. Molecular docking of standard cidofovir along with other ligands, suggested that sofosbuvir has the highest binding energy (-10.8 kcal/mol), followed by baloxavir marboxil (-10.36 kcal/mol). Further, the analysis of molecular interactions using MD simulation (100 ns) and MM-PBSA indicated that baloxavir marboxil has formed the most stable protein-ligand complex with HADV, followed by sofosbuvir. The binding free energies of baloxavir marboxil and sofosbuvir were found to be -61.724 kJ/mol and -48.123 kJ/mol, respectively. The DFT and drug-likeness properties of these compounds were also investigated. Overall, two antiviral agents, such as baloxavir marboxil, and sofosbuvir are suggested as lead repurposed candidates against HADV.Communicated by Ramaswamy H. Sarma.

Abnormal liver function in children hospitalized with acute respiratory infection of adenoviruses: a retrospective study

Human adenoviruses (HAdVs) can cause acute hepatitis in immunocompromised patients. However, it is unclear whether HAdVs are contributors to hepatitis in immunocompetent children. In this study, the liver function test (LFT) results were retrospectively analyzed among children hospitalized (age < 14 years) between January 2016 and October 2019 for acute respiratory infection caused by adenoviruses. Alanine transaminase (ALT) and aspartate aminotransferase (AST) levels were elevated in 7.74% and 46.89% of patients, respectively. All patients with > 2 folds of the upper limit of ALT or AST levels were infected with HAdV-7 or HAdV-55. Significantly higher levels of ALT, AST, γ-glutamyl transpeptidase (γ-GT), and lower albumin levels were observed in the HAdV-7 infection group than in the HAdV-3 infection group. HAdV-55 infection led to significantly higher γ-GT, total bilirubin, and direct bilirubin levels than the other infection types. The records of four patients with serial monitoring of the LFT results were further analyzed. Multiple indicators remained abnormal during the entirehospitalization in these patients. These results indicate that HAdV infection is often accompanied by abnormal liver function, and HAdV-7 and HAdV-55 might be under-recognized contributors to hepatitis among children.

A novel humanized tri-receptor transgenic mouse model of HAdV infection and pathogenesis

Human adenovirus (HAdV) is a highly virulent respiratory pathogen that poses clinical challenges in terms of diagnostics and treatment. Currently, no effective therapeutic drugs or prophylactic vaccines are available for HAdV infections. One factor contributing to this deficiency is that existing animal models, including wild-type and single-receptor transgenic mice, are unsuitable for HAdV proliferation and pathology testing. In this study, a tri-receptor transgenic mouse model expressing the three best-characterized human cellular receptors for HAdV (hCAR, hCD46, and hDSG2) was generated and validated via analysis of transgene insertion, receptor mRNA expression, and protein abundance distribution. Following HAdV-7 infection, the tri-receptor mice exhibited high transcription levels at the early and late stages of the HAdV gene, as well as viral protein expression. Furthermore, the tri-receptor mice infected with HAdV exhibited dysregulated cytokine responses and multiple tissue lesions. This transgenic mouse model represents human HAdV infection and pathogenesis with more accuracy than any other reported animal model. As such, this model facilitates the comprehensive investigation of HAdV pathogenesis as well as the evaluation of potential vaccines and therapeutic modalities for HAdV.

Metabolic bioprofiling of different Glycyrrhiza glabra solvent fractions for the identification of anti-adenoviral compounds using LC-HRMS/MS and in-vitro cytopathic assay coupled with chemometry

Human adenovirus type-7 (HAdV-7) is a common pathogen that may cause significant morbidity as well as severe complications. Currently, there is no approved drug for the treatment of HAdV-7 infections and the contemporary strategy mainly rely on nonspecific antivirals. Glycyrrhiza glabra; (licorice), is a well-recognized edible plant used in food and beverages. The plant is renowned for its pharmacological and biological activities including antiviral activities against wide range of viruses. The following study reported for the first time the anti-adenoviral activity of licorice extract using in-vitro cytopathic inhibitory assay. Different solvent fractions showed promising activity with IC₅₀ reaching 1.431 μg/ml. Certain fractions had selectivity index (SI) greater than 10 indicating their efficacy together with relatively low cytotoxic effect. Metabolic profiling using LC-HRMS/MS resulted in identification of 41 compounds from licorice fractions. Chemometric modeling using Orthogonal Projections to Latent Structures (OPLS) suggested the compounds; kaempferol-3-O-rutinoside, violanthin, rhamnoliquiritin, isoliquiritigenin isomer, licoagroside B and liquiritin apioside as potential markers against (HAdV-7). Finally, kaempferol-3-O-rutinoside was further confirmed via in-vitro adenovirus inhibitory assay to possess strong antiviral activity with IC₅₀ and CC₅₀ of 54.7 ± 1.93 μM and 655.7 ± 2.22 μM, respectively.

Generation of Human Embryonic Stem Cell-Derived Lung Organoids for Modeling Infection and Replication Differences between Human Adenovirus Types 3 and 55 and Evaluating Potential Antiviral Drugs

Human adenoviruses type 3 (HAdV-3) and type 55 (HAdV-55) are frequently encountered, highly contagious respiratory pathogens with high morbidity rate. In contrast to HAdV-3, one of the most predominant types in children, HAdV-55 is a reemergent pathogen associated with more severe community-acquired pneumonia (CAP) in adults, especially in military camps. However, the infectivity and pathogenicity differences between these viruses remain unknown as in vivo models are not available. Here, we report a novel system utilizing human embryonic stem cells-derived 3-dimensional airway organoids (hAWOs) and alveolar organoids (hALOs) to investigate these two viruses. Firstly, HAdV-55 replicated more robustly than HAdV-3. Secondly, cell tropism analysis in hAWOs and hALOs by immunofluorescence staining revealed that HAdV-55 infected more airway and alveolar stem cells (basal and AT2 cells) than HAdV-3, which may lead to impairment of self-renewal functions post-injury and the loss of cell differentiation in lungs. Additionally, the viral life cycles of HAdV-3 and -55 in organoids were also observed using Transmission Electron Microscopy. This study presents a useful pair of lung organoids for modeling infection and replication differences between respiratory pathogens, illustrating that HAdV-55 has relatively higher replication efficiency and more specific cell tropism in human lung organoids than HAdV-3, which may result in relatively higher pathogenicity and virulence of HAdV-55 in human lungs. The model system is also suitable for evaluating potential antiviral drugs, as demonstrated with cidofovir. IMPORTANCE Human adenovirus (HAdV) infections are a major threat worldwide. HAdV-3 is one of the most predominant respiratory pathogen types found in children. Many clinical studies have reported that HAdV-3 causes less severe disease. In contrast, HAdV-55, a reemergent acute respiratory disease pathogen, is associated with severe community-acquired pneumonia in adults. Currently, no ideal in vivo models are available for studying HAdVs. Therefore, the mechanism of infectivity and pathogenicity differences between human adenoviruses remain unknown. In this study, a useful pair of 3-dimensional (3D) airway organoids (hAWOs) and alveolar organoids (hALOs) were developed to serve as a model. The life cycles of HAdV-3 and HAdV-55 in these human lung organoids were documented for the first time. These 3D organoids harbor different cell types, which are similar to the ones found in humans. This allows for the study of the natural target cells for infection. The finding of differences in replication efficiency and cell tropism between HAdV-55 and -3 may provide insights into the mechanism of clinical pathogenicity differences between these two important HAdV types. Additionally, this study provides a viable and effective in vitro tool for evaluating potential anti-adenoviral treatments.

Identification of functional pathways and potential genes associated with interferon signaling during human adenovirus type 7 infection by weighted gene coexpression network analysis

Human adenovirus type 7 (HAdV-7) can cause severe pneumonia and complications in children. However, the mechanism of pathogenesis and the genes involved remain largely unknown. We collected HAdV-7-infected and mock-infected A549 cells at 24, 48, and 72 hours postinfection (hpi) for RNA sequencing (RNA-Seq) and identified potential genes and functional pathways associated with HAdV-7 infection using weighted gene coexpression network analysis (WGCNA). Based on bioinformatics analysis, 12 coexpression modules were constructed by WGCNA, with the blue, tan, and brown modules significantly positively correlated with adenovirus infection at 24, 48, and 72 hpi, respectively. Functional enrichment analysis indicated that the blue module was mainly enriched in DNA replication and viral processes, the tan module was largely enriched in metabolic pathways and regulation of superoxide radical removal, and the brown module was predominantly enriched in regulation of cell death. qPCR was used to determine transcript abundance of some identified hub genes, and the results were consistent with those from RNA-Seq. Comprehensively analyzing hub genes and differentially expressed genes in the GSE68004 dataset, we identified SOCS3, OASL, ISG15, and IFIT1 as potential candidate genes for use as biomarkers or drug targets in HAdV-7 infection. We propose a multi-target inhibition of the interferon signaling mechanism to explain the association of HAdV-7 infection with the severity of clinical consequences. This study has allowed us to construct a framework of coexpression gene modules in A549 cells infected with HAdV-7, thus providing a basis for identifying potential genes and pathways involved in adenovirus infection and for investigating the pathogenesis of adenovirus-associated diseases.

Roles of Interleukin-6-mediated immunometabolic reprogramming in COVID-19 and other viral infection-associated diseases

Interleukin-6 (IL-6) is a highly pleiotropic glycoprotein factor that can modulate innate and adaptive immunity as well as various aspects of metabolism, including glycolysis, fatty acid oxidation and oxidative phosphorylation. Recently, the expression and release of IL-6 is shown to be significantly increased in numerous diseases related to virus infection, and this increase is positively correlated with the disease severity. Immunity and metabolism are two highly integrated and interdependent systems, the balance between them plays a pivotal role in maintaining body homeostasis. IL-6-elicited inflammatory response is found to be closely associated with metabolic disorder in patients with viral infection. This brief review summarizes the regulatory role of IL-6 in immunometabolic reprogramming among seven viral infection-associated diseases.

Predictive Value of Adenoviral Load for Bronchial Mucus Plugs Formation in Children with Adenovirus Pneumonia

Background. The study aimed to explore risk factors for bronchial mucus plugs (BMP) formation in children with adenovirus (AdV) pneumonia. Methods. A retrospective study was conducted on children with AdV pneumonia who underwent bronchoscopy from January 2019 to December 2019. Children were divided into the BMP group and the control group, depending on whether BMP was formed or not. The clinical information and treatment proposals of the two groups of children were counted and analyzed via multiple logistic regression analysis, ROC curve analysis, and correlation analysis. Results. Among 453 patients with AdV pneumonia, 185 (40.84%) were in the BMP group. Among all the cases, there were 188 patients with a single AdV infection, including 64 (34.04%) in the BMP group and 124 (65.96%) in the control group. The incidence of dyspnea, poor spirits, mixed infections, and other symptoms in the BMP group was higher than in the control group. Children in the BMP group had a longer heat range. C-reactive protein (CRP), lactate dehydrogenase (LDH), D-dimer (DD), and AdV load levels were higher in the MBP group. AdV load, Mycoplasma coinfection, DD, heat range, and LDH were independent risk factors for BMP, among which AdV load was the most significant (AUC = 0.819). AdV load was positively correlated with other risk factors, respectively. AdV load and heat range were independent risk factors for BMP patients with a single AdV infection. Conclusion. AdV load might have important clinical value in predicting BMP development in AdV pneumonia.

Cytokine Responses to Adenovirus and Adenovirus Vectors

The expression of cytokines and chemokines in response to adenovirus infection is tightly regulated by the innate immune system. Cytokine-mediated toxicity and cytokine storm are known clinical phenomena observed following naturally disseminated adenovirus infection in immunocompromised hosts as well as when extremely high doses of adenovirus vectors are injected intravenously. This dose-dependent, cytokine-mediated toxicity compromises the safety of adenovirus-based vectors and represents a critical problem, limiting their utility for gene therapy applications and the therapy of disseminated cancer, where intravenous injection of adenovirus vectors may provide therapeutic benefits. The mechanisms triggering severe cytokine response are not sufficiently understood, prompting efforts to further investigate this phenomenon, especially in clinically relevant settings. In this review, we summarize the current knowledge on cytokine and chemokine activation in response to adenovirus- and adenovirus-based vectors and discuss the underlying mechanisms that may trigger acute cytokine storm syndrome. First, we review profiles of cytokines and chemokines that are activated in response to adenovirus infection initiated via different routes. Second, we discuss the molecular mechanisms that lead to cytokine and chemokine transcriptional activation. We further highlight how immune cell types in different organs contribute to synthesis and systemic release of cytokines and chemokines in response to adenovirus sensing. Finally, we review host factors that can limit cytokine and chemokine expression and discuss currently available and potential future interventional approaches that allow for the mitigation of the severity of the cytokine storm syndrome. Effective cytokine-targeted interventional approaches may improve the safety of systemic adenovirus delivery and thus broaden the potential clinical utility of adenovirus-based therapeutic vectors.

Human adenovirus (HAdV) infection in children with acute respiratory tract infections in Guangzhou, China, 2010-2021: a molecular epidemiology study

BACKGROUND

Human adenovirus (HAdV) infection can cause a variety of diseases. It is a major pathogen of pediatric acute respiratory tract infections (ARIs) and can be life-threatening in younger children. We described the epidemiology and subtypes shifting of HAdV among children with ARI in Guangzhou, China.

METHODS

We conducted a retrospective study of 161,079 children diagnosed with acute respiratory illness at the Guangzhou Women and Children's Medical Center between 2010 and 2021. HAdV specimens were detected by real-time PCR and the hexon gene was used for phylogenetic analysis.

RESULTS

Before the COVID-19 outbreak in Guangzhou, the annual frequency of adenovirus infection detected during this period ranged from 3.92% to 13.58%, with an epidemic peak every four to five years. HAdV demonstrated a clear seasonal distribution, with the lowest positivity in March and peaking during summer (July or August) every year. A significant increase in HAdV cases was recorded for 2018 and 2019, which coincided with a shift in the dominant HAdV subtype from HAdV-3 to HAdV-7. The latter was associated with a more severe disease compared to HAdV-3. The average mortality proportion for children infected with HAdV from 2016 to 2019 was 0.38% but increased to 20% in severe cases. After COVID-19 emerged, HAdV cases dropped to 2.68%, suggesting that non-pharmaceutical interventions probably reduced the transmission of HAdV in the community.

CONCLUSION

Our study provides the foundation for the understanding of the epidemiology of HAdV and its associated risks in children in Southern China.

Clinical and Immunological Characteristics of Patients With Adenovirus Infection at Different Altitude Areas in Tibet, China

Background

The severities of human adenovirus (HAdV) infection are diverse in different areas of Tibet, China, where a large altitude span emerges. Serious consequences may be caused by medical staff if the clinical stages and immunological conditions of patients in high-altitude areas are misjudged. However, the clinical symptoms, immunological characteristics, and environmental factors of HAdV infection patients at different altitude areas have not been well described.

Methods

In this retrospective, multicenter cohort study, we analyzed the data of patients who were confirmed HAdV infection by PCR tests in the General Hospital of Tibet Military Command or CDC (the Center for Disease Control and Prevention) of Tibet Military Command from January 1, 2019, to December 31, 2020. Demographic, clinical, laboratory, radiological, and epidemiological data were collected from medical records system and compared among different altitude areas. The inflammatory cytokines as well as the subsets of monocytes and regulatory T cells of patients were also obtained and analyzed in this study.

Results

Six hundred eighty-six patients had been identified by laboratory-confirmed HAdV infection, including the low-altitude group (n = 62), medium-altitude group (n = 206), high-altitude group (n = 230), and ultra-high-altitude group (n = 188). Referring to the environmental factors regression analysis, altitude and relative humidity were tightly associated with the number of infected patients (P < 0.01). A higher incidence rate of general pneumonia (45.7%) or severe pneumonia (8.0%) occurred in the ultra-high-altitude group (P < 0.05). The incubation period, serial interval, course of the disease, and PCR-positive duration were prolonged to various extents compared with the low-altitude group (P < 0.05). Different from those in low-altitude areas, the levels of IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, G-CSF, GM-CSF, IFN-γ, IP-10, MCP-1, TNF-α, TNF-β, and VEGF in the plasma of the ultra-high-altitude group were increased (P < 0.05), while the proportion of non-classical monocytes and regulatory T cells was decreased (P < 0.05).

Conclusions

The findings of this research indicated that patients with HAdV infection in high-altitude areas had severe clinical symptoms and a prolonged course of disease. During clinical works, much more attention should be paid to observe the changes in their immunological conditions. Quarantine of patients in high-altitude areas should be appropriately extended to block virus shedding.

The Epidemiology, Molecular, and Clinical of Human Adenoviruses in Children Hospitalized With Acute Respiratory Infections

Introduction

Human adenovirus (HAdV) is a common pathogen in children with acute respiratory infections (ARIs). The aim was to describe the epidemiology, molecular, and clinical characteristics of HAdV among children hospitalized with ARIs in Wenzhou in southeastern China.

Methodology

From January 2018 to December 2019, nasopharyngeal swab or sputum specimens were prospectively collected from hospitalized children with ARIs. HAdV was detected using direct immunofluorescence. We used a multiplex PCR assay combined with capillary electrophoresis targeting the hexon gene’s hypervariable region to identify HAdV types 1, 2, 3, 4, 5, 7, 14, 21, 37, 40, 41, and 55. We analyzed the epidemiological, molecular, and clinical data according to the HAdV type.

Results

HAdVs were detected in 1,059 (3.5%) of the total of 30,543 children tested. A total of 947 cases with monotype HAdV identified by the PCR assay were included in the analysis. HAdV-3 (415/947, 43.8%), HAdV-7 (318/947, 33.6%), HAdV-2 (108/947, 11.4%), and HAdV-1 (70/947, 7.4%) were the predominant types. Of the 550 (58.1%) cases detected from December 2018 to August 2019, HAdV-3, and HAdV-7 were the main types. The main diagnoses included 358 cases of pneumonia, 232 cases of tonsillitis, 198 cases of bronchitis, and 159 cases of upper respiratory tract infection (URTI). Among children with pneumonia the main types were HAdV-7 (51.1%), HAdV-3 (36.9%), and HAdV-1 (2.2%). Among children with bronchitis, the main types were HAdV-3 (48.0%), HAdV-7 (28.3%), and HAdV-2 (10.6%). Among children with URTIs, the main types were HAdV-3 (49.7%), HAdV-7 (22.6%), and HAdV-2 (13.2%). Among children with tonsillitis, the main types were HAdV-3 (47.4%), HAdV-2 (22.4%), and HAdV-7 (18.5%). In total, 101 (55.2%) patients required supplemental oxygen, 15 (8.2%) required critical care, and 1 child (0.5%) with HAdV-7 pneumonia died.

Conclusion

HAdV-3 -7, -2, and -1 were the predominant types identified in hospitalized children with ARIs in Wenzhou. From December 2018 to August 2019, there were outbreaks of HAdV-3 and -7. There were significant differences in HAdV types among children with pneumonia, tonsillitis, bronchitis, and URTI. HAdV-7 can cause more severe pneumonia in children than HAdV-3.