A significant outbreak of respiratory human adenovirus infections among children aged 3-6 years in Hokkaido, Japan, in 2023.

Human adenovirus (HAdV) infections present diverse clinical manifestations upon infecting individuals, with respiratory infections predominating in children. We surveyed pediatric hospitalizations due to respiratory HAdV infections across 18 hospitals in Hokkaido Prefecture, Japan, from July 2019 to March 2024, recording 473 admissions. While hospitalizations remained below five cases per week from July 2019 to September 2023, a notable surge occurred in late October 2023, with weekly admissions peaking at 15-20 cases from November to December. There were dramatic shifts in the age distribution of hospitalized patients: during 2019-2021, 1-year-old infants and children aged 3-6 years represented 51.4%-54.8% and 4.1%-13.3%, respectively; however, in 2023-2024, while 1-year-old infants represented 19.0%-20.1%, the proportion of children aged 3-6 years increased to 46.2%-50.0%. Understanding the emergence of significant outbreaks of respiratory HAdV infections and the substantial changes in the age distribution of hospitalized cases necessitates further investigation into the circulating types of HAdV in Hokkaido Prefecture and changes in children's neutralizing antibody titers against HAdV.

Association between adeno-associated virus 2 and severe acute hepatitis of unknown etiology in Japanese children.

INTRODUCTION: Outbreaks of acute hepatitis of unknown etiology (AHUE) in children were reported in Western countries in 2022. Previous studies found that adeno-associated virus 2 (AAV2) and its helper viruses, such as human adenovirus (HAdV) and human herpesvirus-6 (HHV-6), are frequently detected in patients with AHUE. However, the existence of hepatitis associated with AAV2 prior to AHUE outbreaks in 2022 had not yet been investigated. We aimed to investigate the association between AAV2 and pediatric acute hepatitis in Japanese children, as well as the incidence of AAV2-related hepatitis prior to 2022. METHODS: Preserved blood samples obtained from 49 pediatric patients with acute hepatitis between 2017 and 2023 were retrospectively analyzed. Blood samples from 50 children with acute illnesses and 50 children with chronic conditions were used as controls. Viral DNA loads were quantitated using real-time PCR. RESULTS: AAV2 DNA was detected in 12 % (6/49) of acute hepatitis cases but in only one acute illness and none of the chronic-condition control cases. The concentration of AAV2 DNA in the six acute hepatitis cases was higher than that in the acute-illness control case. Co-infection with one or more helper viruses, including HAdV, HHV-6, cytomegalovirus, and Epstein-Barr virus, was observed in five AAV2-positive cases. CONCLUSIONS: Our results indicated the sporadic occurrence of pediatric severe hepatitis associated with AAV2 infection in Japan prior to the AHUE outbreaks in 2022. Our findings suggest that co-infection with AAV2 and helper viruses plays a role in developing severe hepatitis.

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.

Genotypes and Phylogenetic Analysis of Human Adenovirus in Hospitalized Pneumonia and Influenza-Like Illness Patients in Jiangsu Province, China (2013-2021).

Background: Human adenovirus (HAdV) is common pathogens that cause various respiratory diseases. The genetic diversity of viruses caused by recombination is considered to be the main source of emerging outbreaks. The aim of this study is to explore the evolutionary relationship and recombination events of HAdV genome in respiratory tract infections in Jiangsu Province. Methods: Whole-genome sequencing (WGS) technology was used to sequence 66 patients with HAdV infection (37 patients with influenza-like illness (ILI) and 29 hospitalized patients with pneumonia) from Jiangsu Province. Epidemiological analysis was performed on hospitalized pneumonia and ILI patients infected with HAdV. Subsequently, phylogenetic, recombination, and nucleotide and amino acid identity analyses were performed. Results: Epidemiological analysis of patients undergoing WGS showed that 75.7% of ILI patients were infected with the HAdVB strain and 69.0% of hospitalized pneumonia patients were infected with the HAdVC strain. Moreover, the hospitalized pneumonia and ILI patients infected with HAdV were different in region and time. The strains of HAdVB3 and HAdVB7 genotypes were mainly infected in 2015 and 2017, and the strains of HAdVC1 and HAdVC2 genotypes were mainly infected in 2020. The results of histogram analysis showed that the HAdV strain mainly infected children under 5 years old. In addition, 36 novel recombinant strains were identified. The discovery of these recombinant strains may contribute to understanding the epidemiology of HAdV and research on related vaccines. Furthermore, the percentage of nucleotide and amino acid identities revealed a high level of genetic conservation within isolates from HAdVB3, HAdVB7, HAdVC1, HAdVC2 and HAdVC5 genotypes. Conclusion: The WGS analysis reveals the evolutionary relationships and recombination events of HAdV strains in Jiangsu Province, which is helpful to deepen the understanding of HAdV epidemiology and evolution. In addition, it provides a basis for the formulation of public health strategies in Jiangsu Province.

Prevalence of human adenovirus type 3 associated with pharyngoconjunctival fever in children in Osaka, Japan during and after the COVID-19 pandemic.

Since the COVID-19 pandemic has affected the epidemiological pattern of pharyngoconjunctival fever (PCF) caused by human adenovirus (HAdV), the prevalence and type distribution of HAdVs associated with PCF among children in Osaka, Japan, between 2019 and 2023 have been analyzed. The number of reported PCF cases in Osaka decreased from 2020 to 2022, followed by an unprecedented increase in 2023. HAdV-C strains, including types C1, C2, and C5, were annually detected in pathogen surveillance in Osaka. HAdV-B3 was not detected for 2 years and 9 months from March 2020, and the number of detections increased from July 2023. In total, HAdV-B3 was the most frequently detected (27 of 52 strains), and genetic analysis of its hexon hypervariable regions showed that, except for one strain, the HAdV-B3 strains identified after 2022 had different amino acid substitutions compared to those identified in 2019 and 2020. These results suggest that the PCF epidemic in 2023 was predominantly caused by variant strains of HAdV-B3, and children who have not acquired immunity against HAdV-B3 between 2020 and 2022 were thought to be infected. The impact of COVID-19 on the prevalence of HAdV infections needs to be continuously evaluated through surveillance.

Global investigation of the presence of adenovirus in different types of water resources: a systematic review.

Waterborne viruses such as adenoviruses cause major health problems in the world. Human adenoviruses are the second leading cause of childhood gastroenteritis worldwide. In recent years, the presence of the virus in aquatic resources has been shown in several studies. In this paper, the global presence of adenovirus in different types of water resources are reviewed through studying several surveys conducted in different countries worldwide. We designed one search study to collect the maximum number of related articles to this subject in international databases search engine via relevant keywords. After reviewing the articles, the most relevant ones were selected, and after classification and extracting the required information, they were reported in the tables presented in this study. In general, it was found that the highest rate of the presence of adenoviruses has been reported in sewage water, inlet, and outlet of the treatment plant while the lowest rate of the presence of adenovirus in the dam water. These findings demonstrate that treatment plant system has weakness in removing the adenovirus and are strongly recommended for treatment plants to use new and better protocols to remove this virus. In addition, appropriate diagnostic methods that combines molecular biological technique with infectivity assay should be implemented for detection of adenoviruses in water resources.

Oncolytic Adenovirus for the Targeting of Paclitaxel-Resistant Breast Cancer Stem Cells.

Adjuvant systemic therapies effectively reduce the risk of breast cancer recurrence and metastasis, but therapy resistance can develop in some patients due to breast cancer stem cells (BCSCs). Oncolytic adenovirus (OAd) represents a promising therapeutic approach as it can specifically target cancer cells. However, its potential to target BCSCs remains unclear. Here, we evaluated a Cox-2 promoter-controlled, Ad5/3 fiber-modified OAd designed to encode the human sodium iodide symporter (hNIS) in breast cancer models. To confirm the potential of OAds to target BCSCs, we employed BCSC-enriched estrogen receptor-positive (ER+) paclitaxel-resistant (TaxR) cells and tumorsphere assays. OAd-hNIS demonstrated significantly enhanced binding and superior oncolysis in breast cancer cells, including ER+ cells, while exhibiting no activity in normal mammary epithelial cells. We observed improved NIS expression as the result of adenovirus death protein deletion. OAd-hNIS demonstrated efficacy in targeting TaxR BCSCs, exhibiting superior killing and hNIS expression compared to the parental cells. Our vector was capable of inhibiting tumorsphere formation upon early infection and reversing paclitaxel resistance in TaxR cells. Importantly, OAd-hNIS also destroyed already formed tumorspheres seven days after their initiation. Overall, our findings highlight the promise of OAd-hNIS as a potential tool for studying and targeting ER+ breast cancer recurrence and metastasis.

In Silico Intensive Analysis for the E4 Gene Evolution of Human Adenovirus Species D.

Adenovirus (Ad) is a ubiquitous pathogen capable of infecting a wide range of animals and humans. Human Adenovirus (HAdV) can cause severe infection, particularly in individuals with compromised immune systems. To date, over 110 types of HAdV have been classified into seven species from A to G, with the majority belonging to the human adenovirus species D (HAdV-D). In the HAdV-D, the most significant factor for the creation of new adenovirus types is homologous recombination between viral genes involved in determining the virus tropism or evading immune system of host cells. The E4 gene, consisting of seven Open Reading Frames (ORFs), plays a role in both the regulation of host cell metabolism and the replication of viral genes. Despite long-term studies, the function of each ORF remains unclear. Based on our updated information, ORF2, ORF3, and ORF4 have been identified as regions with relatively high mutations compared to other ORFs in the E4 gene, through the use of in silico comparative analysis. Additionally, we managed to visualize high mutation sections, previously undetectable at the DNA level, through a powerful amino acid sequence analysis tool known as proteotyping. Our research has revealed the involvement of the E4 gene in the evolution of human adenovirus, and has established accurate sequence information of the E4 gene, laying the groundwork for further research.

Combining CRISPR-Cas-mediated terminal resolution with a novel genetic workflow to achieve high-diversity adenoviral libraries.

While recombinant adenoviruses (rAds) are widely used in both laboratory and medical gene transfer, library-based applications using this vector platform are not readily available. Recently, we developed a new method, the CRISPR-Cas9 mediated in vivo terminal resolution aiding high-efficiency rescue of rAds from recombinant DNA. Here we report on a genetic workflow that allows construction of bacterial artificial chromosome-based rAd libraries reconstituted using highly efficient terminal resolution. We utilized frequent, pre-existing genomic sequences to allow the insertion of a selection marker, complementing two selected target sites into novel endonuclease recognition sites. In the second step, this selection marker is replaced with a transgene or mutation of interest via Gibson assembly. Our approach does not cause unwanted genomic off-target mutations while providing substantial flexibility for the site and nature of the genetic modification. This new genetic workflow, which we termed half site-directed fragment replacement (HFR) allows the introduction of more than 106 unique modifications into rAd encoding BACs using laboratory scale methodology. To demonstrate the power of HFR, we rescued barcoded viral vector libraries yielding a diversity of approximately 2.5 × 104 unique rAds per cm2 of transfected cell culture.

Human adenovirus outbreak at a university campus monitored by wastewater and clinical surveillance.

Areas of dense population congregation are prone to experience respiratory virus outbreaks. We monitored wastewater and clinic patients for the presence of respiratory viruses on a large, public university campus. Campus sewer systems were monitored in 16 locations for the presence of viruses using next generation sequencing over 22 weeks in 2023. During this period, we detected a surge in human adenovirus (HAdV) levels in wastewater. Hence, we initiated clinical surveillance at an on-campus clinic from patients presenting with acute respiratory infection. From whole genome sequencing of 123 throat and/or nasal swabs collected, we identified an outbreak of HAdV, specifically of HAdV-E4 and HAdV-B7 genotypes overlapping in time. The temporal dynamics and proportions of HAdV genotypes found in wastewater were corroborated in clinical infections. We tracked specific single nucleotide polymorphisms (SNPs) found in clinical virus sequences and showed that they arose in wastewater signals concordant with the time of clinical presentation, linking community transmission of HAdV to the outbreak. This study demonstrates how wastewater-based epidemiology can be integrated with surveillance at ambulatory healthcare settings to monitor areas prone to respiratory virus outbreaks and provide public health guidance.

Remarkable increase in the detection and molecular characterization of adenovirus F41 in children with acute gastroenteritis in Japan, 2017-2023.

Human adenovirus (HAdV) is one of the causative viruses of acute gastroenteritis (AGE) in children worldwide. Species F is known to be enteric adenovirus (genotypes 40 and 41) detected in stool samples. In Japan, we conducted an epidemiological study and molecular characterization of HAdV before and after the COVID-19 pandemic from 2017 to 2023. Among 821 patients, HAdV was detected in 118 AGE cases (14.4%). During a period of 6 years, the HAdV detection rates for each year were relatively low at 3.7% and 0%, in 2017-2018, and 2020-2021, respectively. However, the detection rate increased to remarkably high rates, ranging from 13.3% to 27.3% in the other 4-year periods. Of these HAdV-positive strains, 83.1% were F41 genotypes and 16.9% were other genotypes (A31, B3, C1, C2/C6, and C5). Phylogenetic analyses of the nucleotide and deduced amino acid sequences of the full-length hexon gene demonstrated that HAdV-F41 strains were comprised of three clades, and each clade was distributed across the study period from 2017 to 2023. Analysis of deduced amino acid sequences of the hexon gene of the representative HAdV-F41 strains from each clade revealed numerous amino acid substitutions across hypervariable regions (HVRs) from HVR-1 to HVR-7, two insertions in HVR-1 and HVR-7, and two deletions in HVR-1 and HVR-2 of the hexon gene compared to those of the prototype strain, particularly, those of clade 3 HAdV-F41 strains. The findings suggested that the HAdV-F41 of each clade was stable, conserved, and co-circulated for over two decades in Japan.

Genetic characterization of pediatric SARI-associated human adenoviruses in eight Chinese provinces during 2017-2021.

Human adenovirus (HAdV) is a significant viral pathogen causing severe acute respiratory infections (SARIs) in children. To improve the understanding of type distribution and viral genetic characterization of HAdV in severe cases, this study enrolled 3404 pediatric SARI cases from eight provinces of China spanning 2017-2021, resulting in the acquisition of 112 HAdV strains. HAdV-type identification, based on three target genes (penton base, hexon, and fiber), confirmed the diversity of HAdV types in SARI cases. Twelve types were identified, including species B (HAdV-3, 7, 55), species C (HAdV-1, 2, 6, 89, 108, P89H5F5, Px1/Ps3H1F1, Px1/Ps3H5F5), and E (HAdV-4). Among these, HAdV-3 exhibited the highest detection rate (44.6%), followed by HAdV-7 (19.6%), HAdV-1 (12.5%), and HAdV-108 (9.8%). All HAdV-3, 7, 55, 4 in this study belonged to dominant lineages circulating worldwide, and the sequences of the three genes demonstrated significant conservation and stability. Concerning HAdV-C, excluding the novel type Px1/Ps3H1F1 found in this study, the other seven types were detected both in China and abroad, with HAdV-1 and HAdV-108 considered the two main types of HAdV-C prevalent in China. Two recombinant strains, including P89H5F5 and Px1/Ps3H1F1, could cause SARI as a single pathogen, warranting close monitoring and investigation for potential public health implications. In conclusion, 5 years of SARI surveillance in China provided crucial insights into HAdV-associated respiratory infections among hospitalized pediatric patients.

DMSO and Its Role in Differentiation Impact Efficacy of Human Adenovirus (HAdV) Infection in HepaRG Cells.

Differentiated HepaRG cells are popular in vitro cell models for hepatotoxicity studies. Their differentiation is usually supported by the addition of dimethyl sulfoxide (DMSO), an amphipathic solvent widely used in biomedicine, for example, in potential novel therapeutic drugs and cryopreservation of oocytes. Recent studies have demonstrated drastic effects, especially on epigenetics and extracellular matrix composition, induced by DMSO, making its postulated inert character doubtful. In this work, the influence of DMSO and DMSO-mediated modulation of differentiation on human adenovirus (HAdV) infection of HepaRG cells was investigated. We observed an increase in infectivity of HepaRG cells by HAdVs in the presence of 1% DMSO. However, this effect was dependent on the type of medium used for cell cultivation, as cells in William's E medium showed significantly stronger effects compared with those cultivated in DMEM. Using different DMSO concentrations, we proved that the impact of DMSO on infectability was dose-dependent. Infection of cells with a replication-deficient HAdV type demonstrated that the mode of action of DMSO was based on viral entry rather than on viral replication. Taken together, these results highlight the strong influence of the used cell-culture medium on the performed experiments as well as the impact of DMSO on infectivity of HepaRG cells by HAdVs. As this solvent is widely used in cell culture, those effects must be considered, especially in screening of new antiviral compounds.

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.

Activation of the NLRP3 inflammasome by human adenovirus type 7 L4 100-kilodalton protein.

Human adenovirus type 7 (HAdV-7) is a significant viral pathogen that causes respiratory infections in children. Currently, there are no specific antiviral drugs or vaccines for children targeting HAdV-7, and the mechanisms of its pathogenesis remain unclear. The NLRP3 inflammasome-driven inflammatory cascade plays a crucial role in the host's antiviral immunity. Our previous study demonstrated that HAdV-7 infection activates the NLRP3 inflammasome. Building upon this finding, our current study has identified the L4 100 kDa protein encoded by HAdV-7 as the primary viral component responsible for NLRP3 inflammasome activation. By utilizing techniques such as co-immunoprecipitation, we have confirmed that the 100 kDa protein interacts with the NLRP3 protein and facilitates the assembly of the NLRP3 inflammasome by binding specifically to the NACHT and LRR domains of NLRP3. These insights offer a deeper understanding of HAdV-7 pathogenesis and contribute to the development of novel antiviral therapies.

Genomic Evolution and Recombination Dynamics of Human Adenovirus D Species: Insights from Comprehensive Bioinformatic Analysis.

Human adenoviruses (HAdVs) can infect various epithelial mucosal cells, ultimately causing different symptoms in infected organ systems. With more than 110 types classified into seven species (A-G), HAdV-D species possess the highest number of viruses and are the fastest proliferating. The emergence of new adenovirus types and increased diversity are driven by homologous recombination (HR) between viral genes, primarily in structural elements such as the penton base, hexon and fiber proteins, and the E1 and E3 regions. A comprehensive analysis of the HAdV genome provides valuable insights into the evolution of human adenoviruses and identifies genes that display high variation across the entire genome to determine recombination patterns. Hypervariable regions within genetic sequences correlate with functional characteristics, thus allowing for adaptation to new environments and hosts. Proteotyping of newly emerging and already established adenoviruses allows for prediction of the characteristics of novel viruses. HAdV-D species evolved in a direction that increased diversity through gene recombination. Bioinformatics analysis across the genome, particularly in highly variable regions, allows for the verification or re-evaluation of recombination patterns in both newly introduced and pre-existing viruses, ultimately aiding in tracing various biological traits such as virus tropism and pathogenesis. Our research does not only assist in predicting the emergence of new adenoviruses but also offers critical guidance in regard to identifying potential regulatory factors of homologous recombination hotspots.

Genetic Diversity of the Human Adenovirus C Isolated from Hospitalized Children in Russia (2019-2022).

The human adenovirus (HAdV) is a common pathogen in children that can cause acute respiratory virus infection (ARVI). However, the molecular epidemiological and clinical information relating to HAdV among hospitalized children with ARVI is rarely reported in Russia. A 4-year longitudinal (2019-2022) study among hospitalized children (0-17 years old) with ARVI in Novosibirsk, Russia, was conducted to evaluate the epidemiological and molecular characteristics of HAdV. Statistically significant differences in the detection rates of epidemiological and virological data of all positive viral detections of HAdV were analyzed using a two-tailed Chi-square test. The incidence of HAdV and other respiratory viruses such as human influenza A and B viruses, respiratory syncytial virus, coronavirus, parainfluenza virus, metapneumovirus, rhinovirus, bocavirus, and SARS-CoV-2 was investigated among 3190 hospitalized children using real-time polymerase chain reaction. At least one of these respiratory viruses was detected in 74.4% of hospitalized cases, among which HAdV accounted for 4%. A total of 1.3% co-infections with HAdV were also registered. We obtained full-genome sequences of 12 HAdVs, which were isolated in cell cultures. Genetic analysis revealed the circulation of adenovirus of genotypes C1, C2, C5, C89, and 108 among hospitalized children in the period from 2019-2022.

Wastewater-Based Epidemiology for Viral Surveillance from an Endemic Perspective: Evidence and Challenges.

Wastewater-based epidemiology (WBE) is currently used to monitor not only the spread of the viral SARS-CoV-2 pandemic but also that of other viruses in endemic conditions, particularly in the absence of syndromic surveillance. The continuous monitoring of sewage requires high expenditure and significant time investments, highlighting the need for standardized methods and structured monitoring strategies. In this context, we conducted weekly wastewater monitoring in northwestern Tuscany (Italy) and targeted human adenovirus (HAdV), norovirus genogroup II (NoVggII), enterovirus (EV), and SARS-CoV-2. Samples were collected at the entrances of treatment plants and concentrated using PEG/NaCl precipitation, and viral nucleic acids were extracted and detected through real-time reverse transcription qPCR. NoVggII was the most identified target (84.4%), followed by HAdV, SARS-CoV-2, and EV. Only HAdV and EV exhibited seasonal peaks in spring and summer. Compared with data that were previously collected in the same study area (from February 2021 to September 2021), the results for SARS-CoV-2 revealed a shift from an epidemic to an endemic pattern, at least in the region under investigation, which was likely due to viral mutations that led to the spreading of new variants with increased resistance to summer environmental conditions. In conclusion, using standardized methods and an efficient monitoring strategy, WBE proves valuable for viral surveillance in pandemic and epidemic scenarios, enabling the identification of temporal-local distribution patterns that are useful for making informed public health decisions.

Enteric viruses other than rotavirus and norovirus in children under 5 years of age with gastroenteritis in Argentina, 2010-2021. A descriptive study. / Virus entéricos distintos de rotavirus y norovirus en menores de 5 años con gastroenteritis en Argentina, 2010-2021. Estudio descriptivo.

Introduction. Data on the frequency of enteric adenoviruses, sapoviruses, and astroviruses in cases of sporadic acute gastroenteritis in Argentina are scarce. Methods. Descriptive design of a selection of fecal samples of children with diarrhea younger than 5 years referred between 2010 and 2021, with a previous negative result for rotavirus and norovirus. The presence of enteric adenovirus, sapovirus, and astrovirus was tested by molecular methods, with subsequent genotyping of positive samples. Results. At least 1 of the tested viruses was detected in 226 (39.4%) of the 574 selected samples. Specifically, adenovirus, sapovirus, and astrovirus were detected in 30.7%, 5.6%, and 3.1% of the samples, respectively. The most frequent viruses detected were adenovirus 41, sapoviruses GI.1 and GI.2, and astrovirus 1. Non-classic astroviruses were detected in 2 samples. Conclusions. Despite being less frequent, these enteropathogens are responsible for a large number of sporadic diarrhea events. Therefore, their study and surveillance contribute significantly to reduce the gap of undiagnosed cases.

Introducción. Los datos de frecuencia de los adenovirus entéricos, sapovirus y astrovirus en casos de gastroenteritis aguda esporádica en Argentina son escasos. Métodos. Diseño descriptivo sobre una selección de muestras de heces de menores de 5 años con diarrea remitidas durante el período 2010-2021, con resultado previo negativo para rotavirus y norovirus. Se estudió la presencia de adenovirus entéricos, sapovirus y astrovirus por métodos moleculares, con posterior genotipificación de las muestras positivas. Resultados. De 574 muestras seleccionadas, en 226 (39,4 %) se identificó al menos uno de los virus estudiados. En particular, se detectaron adenovirus, sapovirus y astrovirus en el 30,7 %, el 5,6 % y el 3,1 %, respectivamente. El adenovirus 41, los sapovirus GI.1 y GI.2, y el astrovirus 1 fueron los más frecuentemente detectados. Se identificaron dos muestras con astrovirus no clásicos. Conclusiones. A pesar de ser menos frecuentes, estos enteropatógenos son responsables de un número considerable de episodios de diarrea esporádica. Por lo tanto, su estudio y vigilancia contribuye significativamente a reducir la brecha de casos no diagnosticados.

Isolation of a recombinant simian adenovirus encoding the human adenovirus G52 hexon suggests a simian origin for human adenovirus G52.

Human adenoviruses (HAdVs) are causative agents of morbidity and mortality throughout the world. These double-stranded DNA viruses are phylogenetically classified into seven different species (A-G). HAdV-G52, originally isolated in 2008 from a patient presenting with gastroenteritis, is the sole human-derived member of species G. Phylogenetic analysis previously suggested that HAdV-G52 may have a simian origin, indicating a potential zoonotic spillover into humans. However, evidence of HAdV-G52 in either human or simian populations has not been reported since. Here, we describe the isolation and in vitro characterization of rhesus (rh)AdV-69, a novel simian AdV with clear evidence of recombination with HAdV-G52, from the stool of a rhesus macaque. Specifically, the rhAdV-69 hexon capsid protein is 100% identical to that of HAdV-G52, whereas the remainder of the genome is most similar to rhAdV-55, sharing 95.36% nucleic acid identity. A second recombination event with an unknown adenovirus (AdV) is evident at the short fiber gene. From the same sample, we also isolated a second, highly related recombinant AdV (rhAdV-68) that harbors a distinct hexon gene but nearly identical backbone compared to rhAdV-69. In vitro, rhAdV-68 and rhAdV-69 demonstrate comparable growth kinetics and tropisms in human cell lines, nonhuman cell lines, and human enteroids. Furthermore, we show that coinfection of highly related AdVs is not unique to this sample since we also isolated coinfecting rhAdVs from two additional rhesus macaque stool samples. Our data collectively contribute to elucidating the origins of HAdV-G52 and provide insights into the frequency of coinfections and subsequent recombination in AdV evolution.IMPORTANCEUnderstanding the host origins of adenoviruses (AdVs) is critical for public health as transmission of viruses from animals to humans can lead to emergent viruses. Recombination between animal and human AdVs can also produce emergent viruses. HAdV-G52 is the only human-derived member of the HAdV G species. It has been suggested that HAdV-G52 has a simian origin. Here, we isolated from a rhesus macaque, a novel rhAdV, rhAdV-69, that encodes a hexon protein that is 100% identical to that of HAdV-G52. This observation suggests that HAdV-G52 may indeed have a simian origin. We also isolated a highly related rhAdV, differing only in the hexon gene, from the same rhesus macaque stool sample as rhAdV-69, illustrating the potential for co-infection of closely related AdVs and recombination at the hexon gene. Furthermore, our study highlights the critical role of whole-genome sequencing in understanding AdV evolution and monitoring the emergence of pathogenic AdVs.