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The adenovirus vector platform remains one of the most efficient toolboxes for generation of transfer vehicles used in gene therapy and virotherapy to treat tumors, as well as vaccines to protect from infectious diseases. The adenovirus genome and capsids can be modified using highly efficient techniques, and vectors can be produced at high titers, which facilitates their rapid adaptation to current needs and disease applications. Over recent years, the adenovirus vector platform has been in the center of attention for vaccine development against the ongoing coronavirus SARS-CoV-2/COVID-19 pandemic. The worldwide deployment of these vaccines has greatly deepened the knowledge on virus-host interactions and highlighted the need to further improve the effectiveness and safety not only of adenovirus-based vaccines but also of gene therapy and oncolytic virotherapy vectors. Based on the current evidence, we discuss here how adenoviral vectors can be further improved by intelligent molecular design. This review covers the full spectrum of state-of-the-art strategies to avoid vector-induced side effects ranging from the vectorization of non-canonical adenovirus types to novel genome engineering techniques. [ABSTRACT FROM AUTHOR]

Rhinoviruses (RV) account for a significant number of asthma exacerbations, and RV species C may be associated with a severe course in vulnerable patient groups. Despite important evidence on the role of RV reported by clinicians and life scientists, there are still unanswered questions regarding their influence on asthma exacerbation in young patients. Thus, we measured the RVspecies-specific IgG titers in our German pediatric exacerbation cohort using a microarray-based technology. For this approach, human sera of patients with exacerbated asthma and wheeze, as well as healthy control subjects (n = 136) were included, and correlation analyses were performed. Concordantly with previously published results, we observed significantly higher cumulative levels of RV species A-specific IgG (p = 0.011) and RV-C-specific IgG (p = 0.051) in exacerbated asthma group compared to age-matched controls. Moreover, atopic wheezers had increased RV-specific IgG levels for species A (p = 0.0011) and species C (p = 0.0009) compared to non-atopic wheezers. Hypothesizing that bacterial infection positively correlates with immune memory against RV, we included nasopharyngeal swab results in our analyses and detected limited correlations. Interestingly, the eosinophil blood titer positively correlated with RV-specific IgG levels. With these observations, we add important observations to the existing data regarding exacerbation in pediatric and adolescent medicine. We propose that scientists and clinicians should pay more attention to the relevance of RV species in susceptible pediatric patients. [ABSTRACT FROM AUTHOR]

Respiratory viruses play an important role in asthma exacerbation, and early exposure can be involved in recurrent bronchitis and the development of asthma. The exact mechanism is not fully clarified, and pathogen-to-host interaction studies are warranted to identify biomarkers of exacerbation in the early phase. Only a limited number of international exacerbation cohorts were studied. Here, we have established a local pediatric exacerbation study in Germany consisting of children with asthma or chronic, recurrent bronchitis and analyzed the viriome within the nasopharyngeal swab specimens derived from the entire cohort (n = 141). Interestingly, 41% of exacerbated children had a positive test result for human rhinovirus (HRV)/human enterovirus (HEV), and 14% were positive for respiratory syncytial virus (RSV). HRV was particularly prevalent in asthmatics (56%), wheezers (50%), and atopic (66%) patients. Lymphocytes were decreased in asthmatics and in HRV-infected subjects, and patients allergic to house dust mites were more susceptible to HRV infection. Our study thus confirms HRV infection as a strong 'biomarker' of exacerbated asthma. Further longitudinal studies will show the clinical progress of those children with a history of an RSV or HRV infection. Vaccination strategies and novel treatment guidelines against HRV are urgently needed to protect those high-risk children from a serious course of disease. [ABSTRACT FROM AUTHOR]

GABAA receptors are ligand-gated chloride channels and ionotropic receptors of GABA, the main inhibitory neurotransmitter in vertebrates. In this review, we discuss the major and diverse roles GABAA receptors play in the regulation of neuronal communication and the functioning of the brain. GABAA receptors have complex electrophysiological properties that enable them to mediate different types of currents such as phasic and tonic inhibitory currents. Their activity is finely regulated by membrane voltage, phosphorylation and several ions. GABAA receptors are pentameric and are assembled from a diverse set of subunits. They are subdivided into numerous subtypes, which differ widely in expression patterns, distribution and electrical activity. Substantial variations in macroscopic neural behavior can emerge from minor differences in structure and molecular activity between subtypes. Therefore, the diversity of GABAA receptors widens the neuronal repertoire of responses to external signals and contributes to shaping the electrical activity of neurons and other cell types. [ABSTRACT FROM AUTHOR]

SARS-CoV-2 is a new human coronavirus (CoV), which emerged in China in late 2019 and is responsible for the global COVID-19 pandemic that caused more than 97 million infections and 2 million deaths in 12 months. Understanding the origin of this virus is an important issue, and it is necessary to determine the mechanisms of viral dissemination in order to contain future epidemics. Based on phylogenetic inferences, sequence analysis and structure–function relationships of coronavirus proteins, informed by the knowledge currently available on the virus, we discuss the different scenarios on the origin—natural or synthetic—of the virus. The data currently available are not sufficient to firmly assert whether SARS-CoV2 results from a zoonotic emergence or from an accidental escape of a laboratory strain. This question needs to be solved because it has important consequences on the risk/benefit balance of our interactions with ecosystems, on intensive breeding of wild and domestic animals, on some laboratory practices and on scientific policy and biosafety regulations. Regardless of COVID-19 origin, studying the evolution of the molecular mechanisms involved in the emergence of pandemic viruses is essential to develop therapeutic and vaccine strategies and to prevent future zoonoses. This article is a translation and update of a French article published in Médecine/Sciences, August/September 2020 (https://doi.org/10.1051/medsci/2020123). [ABSTRACT FROM AUTHOR]

Type 1 interferons have a broad antiviral activity in vitro and are currently evaluated in a clinical trial to treat MERS-CoV. In this review, we discuss preliminary data concerning the potential activity of type 1 interferons on SARS-CoV-2, and the relevance of evaluating these molecules in clinical trials for the treatment of COVID-19. • Interferon treatment has shown mixed efficiency against SARS-CoV and MERS-CoV. • SARS-CoV-2 is probably more sensitive to interferon than the other coronaviruses. • The IFNβ subtype appears to be the most suited for COVID-19 treatment. • Interferon treatment should be performed in the early stages of the infection. • Investigation on interferon-based COVID-19 treatment is warranted. [ABSTRACT FROM AUTHOR]

As the MHC-I-pathway is key to antigen presentation to cytotoxic T-cells and, therefore, recognition by the host adaptive immune system, we hypothesized that SARS-CoV-2 including its Variants of Concern (VOCs), influences MHC-I expression on epithelial cell surfaces as an immune evasion strategy. We conducted an in vitro time course experiment with the human airway epithelial cell line Calu-3 and the human colorectal adenocarcinoma cell line Caco-2. Cells were infected with SARS-CoV-2 strains non-VOC/B.1.1, Alpha/B.1.1.7, Beta/B.1.351, Gamma/P.1, and Delta/B.1.617.2. At 2, 24, 48 and 72 h post-infection we performed RT-qPCR to track viral replication. Simultaneously, we performed intracellular staining with a serum of a double-vaccinated healthy adult containing a high amount of spike protein antibody. In flow cytometry experiments, we differentiated between infected (spike protein positive) and bystander (spike protein negative) cells. To compare their HLA expression levels, cells were stained extracellularly with anti-HLA-A-IgG and anti-HLA-B,C-IgG. While HLA-A expression was stable on infected Calu-3 cells for all variants, it increased to different degrees on bystander cells in samples infected with VOCs Beta, Gamma, Delta, or non-VOC over the time course analyzed. In contrast, HLA-A levels were stable in bystander Calu-3 cells in samples infected with the Alpha variant. The upregulation of MHC-I on spike protein negative bystander cells in Calu-3 cell cultures infected with Beta, Gamma, Delta, and partly non-VOC might suggest that infected cells are still capable of secreting inflammatory cytokines like type-I interferons stimulating the MHC-I expression on bystander cells. In comparison, there was no distinct effect on HLA expression level on Caco-2 cells of any of the VOCs or non-VOC. Further investigations of the full range of immune evasion strategies of SARS-CoV-2 variants are warranted. [ABSTRACT FROM AUTHOR]

Oncolytic viruses are a promising technology to attack cancer cells and to recruit immune cells to the tumor site. Since the Lipocalin-2 receptor (LCN2R) is expressed on most cancer cells, we used its ligand LCN2 to target oncolytic adenoviruses (Ads) to cancer cells. Therefore, we fused a Designed Ankyrin Repeat Protein (DARPin) adapter binding the knob of Ad type 5 (knob5) to LCN2 to retarget the virus toward LCN2R with the aim of analyzing the basic characteristics of this novel targeting approach. The adapter was tested in vitro with Chinese Hamster Ovary (CHO) cells stably expressing the LCN2R and on 20 cancer cell lines (CCLs) using an Ad5 vector encoding luciferase and green fluorescent protein. Luciferase assays with the LCN2 adapter (LA) showed 10-fold higher infection compared with blocking adapter (BA) in CHO cells expressing LCN2R and in cells not expressing the LCN2R. Most CCLs showed an increased viral uptake of LA-bound virus compared with BA-bound virus and for five CCLs viral uptake was comparable to unmodified Ad5. Flow cytometry and hexon immunostainings also revealed increased uptake of LA-bound Ads compared with BA-bound Ads in most tested CCLs. Virus spread was studied in 3D cell culture models and nine CCLs showed increased and earlier fluorescence signals for LA-bound virus compared with BA-bound virus. Mechanistically, we show that the LA increases viral uptake only in the absence of its ligand Enterobactin (Ent) and independently of iron. Altogether, we characterized a novel DARPin-based system resulting in enhanced uptake demonstrating potential for future oncolytic virotherapy. [ABSTRACT FROM AUTHOR]

The power of adeno-associated viral (AAV)-directed evolution for identifying novel vector variants with improved properties is well established, as evidenced by numerous publications reporting novel AAV variants. However, most capsid variants reported to date have been identified using either replication-competent (RC) selection platforms or polymerase chain reaction-based capsid DNA recovery methods, which can bias the selection toward efficient replication or unproductive intracellular trafficking, respectively. A central objective of this study was to validate a functional transduction (FT)-based method for rapid identification of novel AAV variants based on AAV capsid mRNA expression in target cells. We performed a comparison of the FT platform with existing RC strategies. Based on the selection kinetics and function of novel capsids identified in an in vivo screen in a xenograft model of human hepatocytes, we identified the mRNA-based FT selection as the most optimal AAV selection method. Lastly, to gain insight into the mRNA-based selection mechanism driven by the native AAV-p40 promoter, we studied its activity in a range of in vitro and in vivo targets. We found AAV-p40 to be a ubiquitously active promoter that can be modified for cell-type-specific expression by incorporating binding sites for silencing transcription factors, allowing for cell-type-specific library selection. [ABSTRACT FROM AUTHOR]