Human Adenovirus Type Research Articles

Immunostimulatory Profile of Cancer Cell Death by the AdV-Lumc007-Derived Oncolytic Virus 'GoraVir' in Cultured Pancreatic Cancer Cells.

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy which shows unparalleled therapeutic resistance. Oncolytic viruses have emerged as a new treatment approach and convey their antitumor activity through lysis of cancer cells. The therapeutic efficacy of oncolytic viruses is largely dependent on the induction of immunogenic cell death (ICD) and the subsequent antitumor immune responses. However, the concurrent generation of antiviral immune responses may also limit the a virus' therapeutic window. GoraVir is a new oncolytic adenovirus derived from the Human Adenovirus B (HAdV-B) isolate AdV-lumc007 which was isolated from a gorilla and has demonstrated excellent lytic activity in both in vitro and in vivo models of PDAC. In this study, we characterized the immunostimulatory profile of cancer cell death induced by GoraVir and the concerted cellular antiviral responses in three conventional pancreatic cancer cell lines. While GoraVir was shown to induce late apoptotic/necrotic cell death at earlier time points post infection than the human adenovirus type 5 (HAdV-C5), similar levels of ICD markers were expressed. Moreover, GoraVir was shown to induce ICD not dependent on STING expression and regardless of subsequent antiviral responses. Together, these data demonstrate that GoraVir is an excellent candidate for use in oncolytic virotherapy.

Evaluation of Human Mesenchymal Stromal Cells as Carriers for the Delivery of Oncolytic HAdV-5 to Head and Neck Squamous Cell Carcinomas.

Human multipotent mesenchymal stromal cells (hMSCs) are of significant therapeutic interest due to their ability to deliver oncolytic adenoviruses to tumors. This approach is also investigated for targeting head and neck squamous cell carcinomas (HNSCCs). HAdV-5-HexPos3, a recently reported capsid-modified vector based on human adenovirus type 5 (HAdV-5), showed strongly improved infection of both hMSCs and the HNSCC cell line UM-SCC-11B. Given that, we generated life cycle-unmodified and -modified replication-competent HAdV-5-HexPos3 vector variants and analyzed their replication within bone marrow- and adipose tissue-derived hMSCs. Efficient replication was detected for both life cycle-unmodified and -modified vectors. Moreover, we analyzed the migration of vector-carrying hMSCs toward different HNSCCs. Although migration of hMSCs to HNSCC cell lines was confirmed in vitro, no homing of hMSCs to HNSCC xenografts was observed in vivo in mice and in ovo in a chorioallantoic membrane model. Taken together, our data suggest that HAdV-5-HexPos3 is a potent candidate for hMSC-based oncolytic therapy of HNSCCs. However, it also emphasizes the importance of generating optimized in vivo models for the evaluation of hMSC as carrier cells.

Human Adenovirus and Influenza A Virus Exacerbate SARS-CoV-2 Infection in Animal Models.

In this study, we investigated the features of the infectious process by simulating co-infection with SARS-CoV-2 and human adenovirus type 5 (HAdV-5) or influenza A virus (IAV) in vitro and in vivo. The determination of infectious activity of viruses and digital PCR demonstrated that during simultaneous and sequential HAdV-5 followed by SARS-CoV-2 infection in vitro and in vivo, the HAdV-5 infection does not interfere with replication of SARS-CoV-2. The hamsters co-infected and mono-infected with SARS-CoV-2 exhibited nearly identical viral titers and viral loads of SARS-CoV-2 in the lungs. The hamsters and ferrets co-infected by SARS-CoV-2- and IAV demonstrated more pronounced clinical manifestations than mono-infected animals. Additionally, the lung histological data illustrate that HAdV-5 or IAV and SARS-CoV-2 co-infection induces more severe pathological changes in the lungs than mono-infection. The expression of several genes specific to interferon and cytokine signaling pathways in the lungs of co-infected hamsters was more upregulated compared to single infected with SARS-CoV-2 animals. Thus, co-infection with HAdV-5 or IAV and SARS-CoV-2 leads to more severe pulmonary disease in animals.

Development of Oncolytic Vectors Based on Human Adenovirus Type 6 for Cancer Treatment.

Human Adenovirus type 6 (HAdV-C6) is a promising candidate for the development of oncolytic vectors as it has low seroprevalence and the intrinsic ability to evade tissue macrophages. However, its further development as a therapeutic agent is hampered by the lack of convenient cloning methods. We have developed a novel technology when a shuttle plasmid carrying the distal genome parts with modified E1A and E3 regions is recombined in vitro with the truncated HAdV-C6 genome. Using this approach, we have constructed a novel Ad6-hT-GM vector controlled by the hTERT promoter and expressing granulocyte-macrophage colony-stimulating factor (GM-CSF) instead of 6.7K and gp19K E3 proteins. We have demonstrated that control by the hTERT promoter may result in delayed viral replication, which nevertheless does not significantly change the cytotoxic ability of recombinant viruses. The insertion of the transgene by displacing the E3-6.7K/gp19K region does not drastically change the expression patterns of E3 genes; however, mild changes in expression from major late promoter were observed. Finally, we have demonstrated that the treatment of human breast cancer xenografts in murine models with Ad6-hT-GM significantly decreased the tumor volume and improved survival time compared to mock-treated mice.

Highly Sensitive Multiplex Detection of Molecular Biomarkers Using Hybridization Chain Reaction in an Encoded Particle Microfluidic Platform

In the continuous combat against diseases, there is the need for tools that enable an improved diagnostic efficiency towards higher information density combined with reduced time-to-result and cost. Here, a novel fully integrated microfluidic platform, the Evalution™, is evaluated as a potential solution to this need. Encoded microparticles combined with channel-based microfluidics allow a fast, sensitive and simultaneous detection of several disease-related biomarkers. Since the binary code is represented by physically present holes, 210 different codes can be created that will not be altered by light or chemically induced degradation. Exploiting the unique features of this multiplex platform, hybridization chain reaction (HCR) is explored as a generic approach to reach the desired sensitivity. Compared to a non-amplified reference system, the sensitivity was drastically improved by a factor of 104, down to low fM LOD values. Depending on the HCR duration, the assay can be tuned for sensitivity or total assay time, as desired. The huge potential of this strategy was further demonstrated by the successful detection of a multiplex panel of six different nucleic acid targets including viruses and bacteria. The ability to not only discriminate these two categories but, with the same effort, also virus strains (human adenovirus and human bocavirus), virus subtypes (human adenovirus type B and D) and antibiotic-resistant bacteria (Streptococcus pneumonia), exemplifies the specificity of the developed approach. The effective, yet highly simplified, isothermal and protein-enzyme-free signal amplification tool reaches an LOD ranging from as low as 33 ± 4 to 151 ± 12 fM for the different targets. Moreover, direct detection in a clinically relevant sample matrix was verified, resulting in a detection limit of 309 ± 80 fM, approximating the low fM levels detectable with the gold standard analysis method, PCR, without the drawbacks related to protein enzymes, thermal cycling and elaborate sample preparation steps. The reported strategy can be directly transferred as a generic approach for the sensitive and specific detection of various target molecules in multiplex. In combination with the high-throughput capacity and reduced reagent consumption, the Evalution™ demonstrates immense potential in the next generation of diagnostic tools towards more personalized medicine.

Sustained heterologous gene expression in pancreatic islet organoids using adeno-associated virus serotype 8.

Genetic modification of pancreatic islet organoids, assembled in vitro prior to transplantation is an emerging alternative to direct in vivo genetic manipulations for a number of clinical and research applications. We have previously shown that dispersion of islet cells followed by re-aggregation into islet organoids, or pseudoislets, allows for efficient transduction with viral vectors, while maintaining physiological functions of native islets. Among viruses currently used for genetic manipulations, adeno-associated viruses (AAVs) have the most attractive safety profile making them suitable for gene therapy applications. Studies reporting on pseudoislet transduction with AAVs are, however, lacking. Here, we have characterized in detail the performance of AAV serotype 8 in transduction of islet cells during pseudoislet formation in comparison with human adenovirus type 5 (AdV5). We have assessed such parameters as transduction efficiency, expression kinetics, and endocrine cell tropism of AAV8 alone or in combination with AdV5. Data provided within our study may serve as a reference point for future functional studies using AAVs for gene transfer to islet cell organoids and will facilitate further development of engineered pseudoislets of superior quality suitable for clinical transplantation.

Acute liver failure and unique challenges of pediatric liver transplantation amidst a worldwide cluster of adenovirus-associated hepatitis

Investigation into a recent cluster of acute hepatitis in children from the southeastern United States identified human adenovirus (HAdV) DNAemia in all 9 cases. Molecular genotyping in 5 of 9 (56%) children identified HAdV type 41 in all cases (100%). Importantly, 2 children from this cluster progressed rapidly to pediatric acute liver failure (PALF) and required liver transplantation. HAdV type 41, a known cause of self-limited gastroenteritis, has not previously been associated with severe cholestatic hepatitis and liver failure in healthy children. Adenovirus polymerase chain reaction assay and sequencing of amplicons performed on DNA extracted from formalin-fixed, paraffin-embedded liver tissue also identified adenovirus species F (HAdV type 40 or 41) in these 2 children with PALF. Transplant considerations and successful liver transplantation in such situations remain scarce. In this report, we describe the clinical course, laboratory results, liver pathology, and treatment of 2 children with PALF associated with HAdV type 41, one of whom developed secondary hemophagocytic lymphohistiocytosis. Their successful posttransplant outcomes demonstrate the importance of early multidisciplinary medical management and the feasibility of liver transplantation in some children with PALF and HAdV DNAemia.

Uptake without inactivation of human adenovirus type 2 by Tetrahymena pyriformis ciliates.

Human adenoviruses are ubiquitous contaminants of surface water. Indigenous protists may interact with adenoviruses and contribute to their removal from the water column, though the associated kinetics and mechanisms differ between protist species. In this work, we investigated the interaction of human adenovirus type 2 (HAdV2) with the ciliate Tetrahymena pyriformis. In co-incubation experiments in a freshwater matrix, T. pyriformis was found to efficiently remove HAdV2 from the aqueous phase, with ≥4 log10 removal over 72 hours. Neither sorption onto the ciliate nor secreted compounds contributed to the observed loss of infectious HAdV2. Instead, internalization was shown to be the dominant removal mechanism, resulting in the presence of viral particles inside food vacuoles of T. pyriformis, as visualized by transmission electron microscopy. The fate of HAdV2 once ingested was scrutinized and no evidence of virus digestion was found over the course of 48 hours. This work shows that T. pyriformis can exert a dual role in microbial water quality: while they remove infectious adenovirus from the water column, they can also accumulate infectious viruses.

Abstract 2234: CD46 is a protein receptor for Human Adenovirus Type 64

Abstract 2234: CD46 is a protein receptor for Human Adenovirus Type 64

Seroprevalence of Binding and Neutralizing Antibodies against 39 Human Adenovirus Types in Patients with Neuromuscular Disorders.

High pre-existing antibodies against viral vectors reduce their functionality and may lead to adverse complications. To circumvent this problem in future gene therapy approaches, we tested the seroprevalence of a large range of human adenovirus types in patients with neuromuscular disorders (NMDs) to find appropriate viral vector candidates for gene replacement therapy for NMDs. Binding and neutralizing antibodies against 39 human adenovirus types were tested in the sera of 133 patients with NMDs and 76 healthy controls aged 17-92 years. The influence of age, sex, and NMDs on antibody levels was analyzed. The seroprevalence of different adenoviruses in the cohort varied widely. The highest levels of binding antibodies were detected against HAdV-D27, -C1, -D24, -D70, -B14, -C6, -D13, -B34, and -E4, whereas the lowest reactivity was detected against HAdV-F41, -A31, -B11, -D75, -D8, -D65, -D26, -D80, and -D17. The highest neutralizing reactivity was observed against HAdV-B3, -C2, -E4, -C1, -G52, -C5, and -F41, whereas the lowest neutralizing reactivity was observed against HAdV-D74, -B34, -D73, -B37, -D48, -D13, -D75, -D8, -B35, and -B16. We detected no influence of sex and only minor differences between different age groups. Importantly, there were no significant differences between healthy controls and patients with NMDs. Our data show that patients with NMDs have very similar levels of binding and neutralizing antibodies against HAdV compared to healthy individuals, and we identified HAdV-A31, -B16, -B34, -B35, -D8, -D37, -D48, -D73, -D74, -D75, and -D80 as promising candidates for future vector development due to their low binding and neutralizing antibody prevalence.

Influence of Heparan Sulfate Proteoglycans and Factor X on species D Human Adenovirus Uptake and Transduction.

More than 100 human adenovirus (Ad) types were identified, of which species D comprises the largest group. Heparan sulfate proteoglycans (HSPGs) were shown to function as cell surface receptors for cell binding and uptake of some Ads, but a systematic analysis of species D Ads is lacking. Previous research focused on Ad5 and blood coagulation factor X (FX) complexes, which revealed that Ad5 can transduce cells with low expression levels of its main coxsackievirus-adenovirus receptor in the presence of high HSPG expression levels in a FX dependent manner. Based on our reporter gene-tagged Ad-library, we explored for the first time a broad spectrum of species D Ads to study the role of HSPG on their cellular uptake. This study was performed on three Chinese Hamster Ovary (CHO) cell lines with different forms of HSPG (only proteoglycan (745), non-sulfated HSPG (606) or sulfated HSPG (K1)). The effect of Ad:FX complexes on Ad uptake was explored in the presence of physiological levels of FX in blood (6-10 µg/mL). We found that sulfation of HSPG plays an important role in cellular uptake and transduction of FX-bound Ad5 but neither HSPG nor FX influenced uptake of all tested species D Ads. Because FX has no influence on transduction efficiencies of species D Ads and therefore may not bind to them, these Ads may not be protected from attack by neutralizing IgM antibodies or the complement pathway, which may have implications for species D Ads used as vaccine and gene therapy vectors.

Measurement of Adenovirus-Based Vector Heterogeneity

Adenovirus vectors have become an important class of vaccines with the recent approval of Ebola and COVID-19 products. In-process quality attribute data collected during Adenovirus vector manufacturing has focused on particle concentration and infectivity ratios (based on viral genome: cell-based infectivity), and data suggest only a fraction of viral particles present in the final vaccine product are efficacious. To better understand this product heterogeneity, lab-scale preparations of two Adenovirus viral vectors, (Chimpanzee adenovirus (ChAdOx1) and Human adenovirus Type 5 (Ad5), were studied using transmission electron microscopy (TEM). Different adenovirus morphologies were characterized, and the proportion of empty and full viral particles were quantified. These proportions showed a qualitative correlation with the sample's infectivity values. Liquid chromatography-mass spectrometry (LC-MS) peptide mapping was used to identify key adenovirus proteins involved in viral maturation. Using peptide abundance analysis, a ∼5-fold change in L1 52/55k abundance was observed between low-(empty) and high-density (full) fractions taken from CsCl ultracentrifugation preparations of ChAdOx1 virus. The L1 52/55k viral protein is associated with DNA packaging and is cleaved during viral maturation, so it may be a marker for infective particles. TEM and LC-MS peptide mapping are promising higher-resolution analytical characterization tools to help differentiate between relative proportions of empty, non-infectious, and infectious viral particles as part of Adenovirus vector in-process monitoring, and these results are an encouraging initial step to better differentiate between the different product-related impurities.

Molecular Mechanism of Adenovirus Late Protein L4-100K Chaperones the Trimerization of Hexon.

Assembly of the adenovirus capsid protein hexon depends on the assistance of the molecular chaperone L4-100K. However, the chaperone mechanisms remain unclear. In this study, we found that L4-100K was involved in the hexon translation process and could prevent hexon degradation by the proteasome in cotransfected human cells. Two nonadjacent domains, 84-133 and 656-697, at the N-terminal and C-terminal regions of human adenovirus type 5 L4-100K, respectively, were found to be crucial and cooperatively responsible for hexon trimer expression and assembly. These two chaperone-related domains were conserved in the sequence of L4-100K and in the function of hexon assembly across different adenovirus serotypes. Different degrees of cross-activity of hexon trimerization with different serotypes were detected in subgroups B, C, and D, which were proven to be controlled by the interaction between the C-terminal chaperone-related domain of L4-100K and hypervariable regions (HVR) of hexon. Additionally, HVR-chimeric hexon mutants were successfully assembled with the assistance of the 1-697 mutant. Structural analysis of 656-697 by nuclear magnetic resonance and structural prediction of L4-100K using Robetta showed that the two conserved domains are mainly composed of α-helices and are located on the surface of the highly folded core region. Our research provides a more complete understanding of hexon assembly and guidance for the development of hexon-chimeric adenovirus vectors that will be safer, smarter, and more efficient. IMPORTANCE Adenovirus vectors have been widely used in clinical trials of vaccines and gene therapy, although some deficiencies remain. Chimeric modification of the hexon was expected to improve the potency of preexisting immune evasion and targeting, but in many cases, viral packaging is prevented by the inability of the chimeric hexon to assemble correctly. So far, few studies have examined the mechanisms of hexon trimer assembly. Here, we show how the chaperone protein L4-100K contributes to the assembly of the adenovirus capsid protein hexon, and these data will provide a guide for novel adenovirus vector design and development, as we desired.

Ranpirnase (OKG-0301), a Novel Ribonuclease, Demonstrates Antiviral Activity against Adenovirus in the Ad5/NZW Rabbit Ocular Replication Model.

Adenovirus ocular infections are common ocular viral infections seen worldwide, for which there is no approved antiviral therapy available. Ranpirnase is a novel ribonuclease which preferentially degrades tRNA resulting in an inhibition of protein synthesis. The study goal was to determine the anti-adenoviral activity of topical formulations of ranpirnase (OKG-0301) on adenoviral replication in the Ad5/NZW rabbit ocular replication model. NZW rabbits were inoculated in both eyes with human adenovirus type 5 (HAdV5) after corneal scarification. A day later, topical therapy was initiated in both eyes with 0.03% OKG-0301, 0.003% OKG-0301, saline or 0.5% cidofovir. Eyes were cultured to determine HAdV5 eye titers over 2 weeks. OKG-0301 (0.03% and 0.003%) and 0.5% cidofovir decreased viral titers compared to saline. Furthermore, both OKG-0301 formulations and 0.5% cidofovir shortened the duration of the HAdV5 infection compared to saline. Both 0.03% OKG-0301 and 0.003% OKG-0301 demonstrated increased antiviral activity compared to saline in the Ad5/NZW rabbit ocular replication model. The antiviral activity of the OKG-0301 groups was similar to that of the positive antiviral control, 0.5% cidofovir. Ranpirnase (OKG-0301) may be a potential candidate for a topical antiviral for adenoviral eye infections. Further clinical development is warranted.

An efficient capture strategy for the purification of human adenovirus type 5 from cell lysates

An efficient capture step for human adenovirus type 5 from cell lysate was developed as an initial virus purification step from cell debris supernatant. Organosilane-based polymer particles were synthesized and experimental monomer screening allowed the selection of appropriate functionalities for the development of particles for virus binding. After elution, virus recoveries of 83 % were obtained with significant reduction of matrix proteins and residual host cell DNA. Therefore, the implemented capture strategy for adenovirus via polymer particles provides a scalable and reproducible approach to reduce time and cost during virus purification processes.

95P A phase II study of combination of H101 (a recombinant human adenovirus type 5) and nivolumab for advanced hepatocellular carcinoma (HCC) after systemic therapy failure

HCC has a mortality/morbidity ratio of 0.98 and a five-year survival rate of only about 5%-6%, indicating a very poor prognosis. Nivolumab is a programmed death receptor-1 (PD-1) inhibitor. H101, an E1B gene deleted oncolytic adenovirus, is known to have significant antitumor activity. In addition, local injection of H101 might enhance the effect of antitumor therapies (chemotherapy and radiotherapy). We report on the safety and efficacy of H101 in combination with nivolumab in patients (pts) with advanced HCC.

54P Oncolytic virus combined PD-1 antibody toripalimab in advanced lung cancer with liver metastases: An early stage, single arm, study (TROJAN 2201)

The efficacy of checkpoint inhibitors are far from satisfied in lung cancer patients with liver metastases. Oncolytic virus can enhance the efficacy of PD-1/PD-L1 antibody in vitro/vivo. In this study, we evaluate the safety and efficacy of oncolytic virus H101 plus PD-1 antibody Toripalimab for liver metastasis-lung cancer advanced patients who have progressed and failed after EGFR-TKIs, chemotherapy or checkpoint inhibitors treatment. The patients refractory to previous several lines of standard treatment were injected with recombinant human adenovirus 5 (1012 vp or 2×1012vp) locally for liver metastases plus toripalimab (3mg/kg) systemic therapy every 2 weeks until progression or intolerable toxicity. The two primary end points were investigator-assessed safety and objective response rate (ORR) and the secondary end points included progression-free survival (PFS) and disease control rate (DCR). Efficacy was assessed every 2 months by investigators according to mRECIST v1.1 criteria. Blood samples were collected from patients prospectively. From January 26, 2021 to July 15, 2022, ten patients were enrolled and received at least 1 cycle of the combination regimen. The most common treatment-related adverse events (TRAEs) were grade 1-2 fever, which was occurred in 9 (90%) of 10 patients. No deaths and other SAE were judged to be treatment-related. Six among the 10 patients received at least 3 cycles of the combination regimen and 5 were evaluable for efficacy analyses as one patient was lost to follow-up. Two of five (40%) patients (one small cancer and one adenocarcinoma) acquired partial remission (PR) after 3 cycles of the combination therapy, including one patient remained remission for 11 months. Two patients (40%) (one small cancer and one adenocarcinoma) achieved stable disease (SD) and the other one adenocarcinoma patent (20%) had progressive diseases (PD). Our results confirm that the combination of recombinant human adenovirus type 5 plus toripalimab has shown an acceptable safety profile and the preliminary efficacy in those who refractory to previous several lines of standard treatment, deserved further investigation in randomized trials.

Affilin-based retargeting of adenoviral vectors to the epidermal growth factor receptor

IntroductionTreatment of head and neck squamous cell carcinomas (HNSCC) by oncolytic adenoviral vectors holds promise as an efficient anti-cancer therapy. The epidermal growth factor receptor (EGFR) represents an attractive target receptor since it is frequently overexpressed in many types of HNSCC. MethodsTo achieve EGFR-specific targeting by human adenovirus type 5 (HAdV-5) based vectors, the EGFR affinity ligand Affilin was covalently attached in a position specific manner either to the fiber or the hexon protein of the vector capsid. In vitro and in vivo studies investigated EGFR-specific cancer cell transduction, susceptibility to natural sequestration mechanisms, pharmacokinetics and biodistribution profiles of Affilin-decorated vectors. ResultsAffilin-decorated vectors showed strongly enhanced and EGFR-specific cancer cell transduction in vitro and less susceptibility to known sequestration mechanisms of HAdV-5 particles. However, in vivo neither systemic nor intratumoral vector administration resulted in an improved transduction of EGFR-positive tumors. Comprehensive analyses indicated hampered EGFR-targeting by Affilin-decorated vectors was caused by rapid vector particle consumption due to binding to the murine EGFR, insufficient tumor vascularization and poor target accessibility for Affilin in the solid tumor caused by a pronounced tumor stroma. ConclusionIn vitro studies yielded proof-of-concept results demonstrating that covalent attachment of a receptor-specific Affilin to the adenoviral capsid provides an effective and versatile tool to address cancer-specific target receptors by adenoviral vectors. Regarding EGFR as the vector target, off-target tissue transduction and low receptor accessibility within the tumor tissue prevented efficient tumor transduction by Affilin-decorated vectors, rendering EGFR a difficult-to-target receptor for adenoviral vectors.

Analysis of the Prevalence of Binding and Neutralizing Antibodies against 39 Human Adenovirus Types in Student Cohorts Reveals Low-Prevalence Types and a Decline in Binding Antibody Levels during the SARS-CoV-2 Pandemic.

Human adenoviruses (HAdVs) are important tools for vector development for applications such as immunization, oncolytic therapy, or gene therapy. However, their potential is limited by preexisting immunity against HAdV; therefore, it is important for future vector design to identify HAdV types of low seroprevalence. To provide such data, we performed an analysis of both binding and neutralizing antibodies in sera from three student cohorts. Among these young adults, we found the highest levels of binding antibodies against HAdV-C1, -D33, -A31, -B35, -C5, -D26, -E4, and -B7. The highest levels of neutralizing antibodies were detected against HAdV-C2, -B3, -C1, -F41, -G52, -C5, -A31, -E4, and -C6. While binding and neutralizing antibody levels were not different in males and females or in samples collected before and after the cold season, we found significantly lower levels of binding antibodies in sera collected 20 months after the beginning of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, indicating a waning of HAdV-specific antibody responses on that time scale. Our data indicate that mainly HAdV types of species A, B, and D show low seroprevalence with regard to both binding and neutralizing antibodies and may represent good candidates for further characterization and future development as novel vector systems. IMPORTANCE Vectors based on human adenoviruses (HAdVs) are important for the development of novel immunizations, oncolytic therapies, and gene therapies. The use of HAdV-based vaccines against Ebola virus, the rapid adaptation of the vector technology for vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and their very good efficacy have shown the great potential of HAdV-based vaccines. Preexisting immunity against HAdV-based vectors can limit their efficacy significantly; therefore, it is highly desirable to identify HAdV types with low seroprevalence. The identification of new suitable HAdV types for vector development will broaden the repertoire and contribute to future epidemic preparedness.

Severe pneumonia caused by human adenovirus type 55 in children.

BackgroundEmerging human adenovirus type 55 (HAdV-55) causes fatal pneumonia in adults. There is a lack of studies on severe pneumonia caused by HAdV-55 in children.MethodsWe conducted a retrospective review of pediatric patients hospitalized at Guangzhou Women and Children’s Medical Center with severe pneumonia from 2013 to 2020 who had human adenovirus (HAdV) detected in throat samples or bronchoalveolar lavage fluid using RT-PCR. The presence of HAdV-55 was determined by PCR amplification of the hypervariable regions of the hexon gene. Demographic, clinical, etiological, and outcome data were collected and analyzed.ResultsOver the eight-year period, HAdV-55 was detected in three severe and six critical pediatric pneumonia patients. None of the patients had any underlying diseases, and had a median age of 18 months (range, 6–108 months). The male to female ratio was 2:1. All patients presented with fever and cough, and three patients presented with wheezing and diarrhea. Six patients had coinfections with other respiratory pathogens, such as bacteria, Mycoplasma pneumoniae and fungi. Three critical patients developed plastic bronchitis (PB). The median lengths of invasive mechanical ventilation and hospital stay of the critical patients were 10 (8, 28.75) days and 25 (13, 32.25) days, respectively. Three critical patients died, although two of them received extracorporeal membrane oxygenation (ECMO) and blood purification. Three surviving patients developed post-infectious bronchiolitis obliterans (PIBO) at the follow-up.ConclusionsHAdV-55 can cause fatal pneumonia in children, and shows a high rate of co-infection with other respiratory pathogens and a poorer prognosis combined with PB. Thus, HAdV-55 may be an important subtype in patients with HAdV-induced pneumonia who develop PIBO.