Biology subjects

Arnberg, N.

Publications and source records attributed to Arnberg, N..

8 recordsLinked to original sources

bioRxiv2026

Anthracyclines inhibit -1 programmed ribosomal frameshifting and restrict HCoV-OC43 infection

Human coronavirus OC43 (HCoV-OC43) constitutes one of the most common causes of the seasonal cold but can also cause severe disease among elderly and immuno-compromised. Currently, there are no approved antiviral drugs to combat HCoV-OC43 infection. Coronaviruses are positive-sense single-stranded RNA (+ssRNA) viruses and utilize -1 programmed ribosomal frameshifting (-1 PRF) to produce the correct stoichiometry of viral protein components. Due to its high conservation, the ribosomal frameshifting stimulation element (FSE) is a promising target for antiviral drug discovery. Aminoglycosides and anthracyclines interact with structured nucleic acids and some of these compounds affect -1 PRF in SARS-CoV-2. To get a comprehensive view of their putative efficacy, we examined all commercially available aminoglycosides and anthracyclines for their ability to affect -1 PRF in HCoV-OC43 and their potential to reduce HCoV-OC43 infection. Of 25 candidates tested, we identified 3 anthracyclines (Idarubicin, Nogalamycin and Daunorubicin) to reduce HCoV-OC43 -1 PRF using in vitro assays. We further demonstrate that the active anthracyclines, but not the inactive anthracycline, bind to the HCoV-OC43 FSE. The active anthracyclines did not significantly affect -1 PRF in SARS-CoV-2, suggesting differences in the interactions of the anthracyclines and FSEs, despite being relatively conserved in HCoV-OC43 and SARS-CoV-2 RNAs. Interestingly, these potent anthracyclines also significantly reduced HCoV-OC43 infection in human host cells. Although, the anthracyclines show some toxicity and introduce lesions in cellular DNA they could constitute an important scaffold for further antiviral development, with the aim to increase efficacy and reduce toxicity. Author summaryThe recent Covid-19 pandemic caused by SARS-CoV-2 showed the need for functional antivirals to immediately combat infections at the onset of future pandemics. In addition to SARS-CoV-2, four other human coronaviruses can cause mild to severe infection. Among those is HCoV-OC43, a coronavirus particularly troublesome for immunocompromised patients. Despite this clinical relevance, no approved antiviral therapies are currently available for the prevention or treatment of HCoV-OC43 infections. In this work, we have identified a subset of anthracyclines (Idarubicin, Nogalamycin and Daunorubicin) that selectively and significantly reduce HCoV-OC43 infection. In contrast to a non-active anthracycline, the same anthracyclines that reduce infection also reduce ribosomal frameshifting and interact with a structured RNA in the viral RNA-genome. Interestingly, Idarubicin, a clinically used anticancer drug, shows selectivity for HCoV-OC43, but not for SARS-CoV-2 RNA. Our work demonstrates that anthracyclines could be important for pandemic preparedness and serve as attractive scaffolds when developing new antivirals targeting coronaviruses.

microbiology↗

bioRxiv2025

Development of an ex vivo model to study the zoonotic transmission of noroviruses

Human noroviruses are the most common cause of viral gastroenteritis worldwide, causing sporadic cases and outbreaks. Genetically related animal noroviruses infect wild and domestic animals including pigs and dogs. To investigate the potential of noroviruses to jump the species barrier, we used porcine, canine, and avian precision-cut intestinal slices. We show that human norovirus can bind to pig and dog intestinal tissue and be taken up with a similar efficiency as the porcine and canine noroviruses, respectively. In contrast, no binding or internalization of human, porcine, or canine noroviruses was detected in chicken tissue. We further showed that human norovirus can replicate to some degree in pig intestinal tissue, infecting single cells. In contrast, while animal noroviruses attached to human intestinal cells, intracellular uptake was limited. This suggests that human-to-animal transmission is more likely than animal-to-human transmission and that viral uptake likely presents a species barrier.

microbiology↗

bioRxiv2024

Alpha-defensin binding expands human adenovirus tropism

Mammalian -defensins are a family of abundant effector peptides of the mucosal innate immune system. Although primarily considered to be antimicrobial, -defensins can increase rather than block infection by certain prominent bacterial and viral pathogens in cell culture and in vivo. We have shown previously that exposure of mouse and human adenoviruses (HAdVs) to -defensins is able to overcome competitive inhibitors that block cell binding, leading us to hypothesize a defensin-mediated binding mechanism that is independent of known viral receptors. To test this hypothesis, we used genetic approaches to demonstrate that none of several primary receptors nor integrin co-receptors are needed for human -defensin-mediated binding of HAdV to cells; however, infection remains integrin dependent. Thus, our studies have revealed a novel pathway for HAdV binding to cells that bypasses viral primary receptors. We speculate that this pathway functions in parallel with receptor-mediated entry and contributes to -defensin-enhanced infection of susceptible cells. Remarkably, we also found that in the presence of -defensins, HAdV tropism is expanded to non-susceptible cells, even when viruses are exposed to a mixture of both susceptible and non-susceptible cells. Therefore, we propose that in the presence of sufficient concentrations of -defensins, such as in the lung or gut, integrin expression rather than primary receptor expression will dictate HAdV tropism in vivo. In summary, -defensins may contribute to tissue tropism not only through the neutralization of susceptible viruses but also by allowing certain defensin-resistant viruses to bind to cells independently of previously described mechanisms. Author SummaryIn this study, we demonstrate a novel mechanism for binding of human adenoviruses (HAdVs) to cells that is dependent upon interactions with -defensin host defense peptides but is independent of known viral receptors and co-receptors. To block normal receptor-mediated HAdV infection, we made genetic changes to both host cells and HAdVs. Under these conditions, -defensins restored cell binding; however, infection still required the function of HAdV integrin co-receptors. This was true for multiple types of HAdVs that use different primary receptors and for cells that are either naturally devoid of HAdV receptors or were engineered to be receptor deficient. These observations suggest that in the presence of concentrations of -defensins that would be found naturally in the lung or intestine, there are two parallel pathways for HAdV binding to cells that converge on integrins for productive infection. Moreover, these binding pathways function independently, and both operate in mixed culture. Thus, we have found that viruses can co-opt host defense molecules to expand their tropism.

microbiology↗

bioRxiv2023

Structural Insights into the Interaction Between Adenovirus C5 Hexon and Human Lactoferrin

Adenovirus (AdV) infection of the respiratory epithelium is common, but poorly understood. Human AdV species C types, such as HAdV-C5, utilize the Coxsackie-adenovirus receptor (CAR) for attachment and subsequently integrins for entry. CAR and integrins are however located deep within the tight junctions in the mucosa where they would not be easily accessible. Recently, a model for CAR-independent AdV entry was proposed. In this model, human lactoferrin (hLF), an innate immune protein, aids the viral uptake into epithelial cells by mediating interactions between the major capsid protein, hexon, and yet unknown host cellular receptor(s). However, a detailed understanding of the molecular interactions driving this mechanism is lacking. Here, we present a new cryo-EM structure of HAdV-5C hexon at high resolution alongside a hybrid structure of HAdV-5C hexon complexed with human lactoferrin (hLF). These structures reveal the molecular determinants of the interaction between hLF and HAdV-C5 hexon. hLF engages hexon primarily via its N-terminal lactoferricin (Lfcin) region, interacting with hexons hypervariable region 1 (HVR-1). Mutational analyses pinpoint critical Lfcin contacts and also identify additional regions within hLF that critically contribute to hexon binding. Our study sheds more light on the intricate mechanism by which HAdV-C5 utilizes soluble hLF/Lfcin for cellular entry. These findings hold promise for advancing gene therapy applications and inform vaccine development.

biochemistry↗

bioRxiv2023

Bile acids accumulate norovirus-like particles and enhance binding to and entry into human enteric epithelial cells

Human norovirus (HuNoV) is a leading cause of acute viral gastroenteritis, but despite high impact on public health and health care, the mechanisms of viral attachment to and entry into target cells are not yet fully understood. It is well known that body fluids such as blood can transmit unrelated viruses, but recent reports also indicate that saliva and bile contribute to transmission of HuNoV. For example, human bile acids increase cell surface ceramide levels in human enteroids, which improves norovirus entry into cells resulting in enhanced replication. Bile acids can also interact directly with the norovirus capsid, but it is not known whether bile or other gastrointestinal body fluids directly affect HuNoV attachment to host cells. In this study, we investigated the effects of patient-derived gastric juice, pancreatic juice, and bile on HuNoV GII.4 virus-like particle (VLP) attachment to and entry into a human duodenal cell line, HuTu-80. We show that while gastric juice and pancreatic juice do not affect viral attachment or entry, bile - in particular hydrophobic bile acids - significantly enhance cellular attachment and subsequent entry of GII.4 VLPs into cells. In addition, we show that hydrophobic bile acids induce accumulation of viral particles in the vicinity of cells. Our results suggest the presence of a new en masse infection mechanism, where bile acids aggregate virions, and allow direct and more efficient attachment to and entry into target cells. ImportanceViruses transmitted by the fecal-oral route encounter secreted host factors in gastrointestinal fluids. Some host factors can be exploited by the virus to facilitate infection. Human bile acids indirectly promote norovirus entry into and infection of human enteroids, but the direct effect of bile acids on attachment and uptake, along with the impact of other gastrointestinal fluids, remain unknown. Here, we investigated the direct effects of human body fluids on cellular attachment of norovirus VLPs. We show that human bile and hydrophobic bile acids induce an accumulation of norovirus VLPs, which is associated with significantly enhanced attachment and entry into human duodenal cell lines. These results highlight the differential effects of gastrointestinal body fluids on viral attachment and entry, while providing useful information into the complex HuNoV-host interactions that facilitate infection.

microbiology↗

bioRxiv2023

Efficient clathrin-mediated entry of enteric adenoviruses in human duodenal cells

Enteric adenovirus types F40 and 41 (EAdVs) are a leading cause of diarrhea and diarrhea-associated death in young children and have recently been proposed to cause acute hepatitis in children. Unlike other adenoviruses, EAdVs exhibit hitherto a strict tropism for gastrointestinal tissues with, to date, unknown infection mechanism and target cells. In this study, we turn to potentially limiting host factors by comparison of EAdV entry in cell lines with respiratory and intestinal origin by cellular perturbation, virus particle tracking and transmission electron microscopy. Our analyses highlight kinetic advantages in duodenal HuTu80 cell infection and reveal a larger fraction of mobile particles, faster virus uptake and infectious particle entry in intestinal cells. Moreover, EAdVs display a dependence on clathrin- and dynamin-dependent pathways in intestinal cells. Detailed knowledge of virus entry routes and host factor requirements is essential to understand pathogenesis and develop new countermeasures. Hence, this study provides novel insights into the entry mechanisms of a medically important virus with emerging tropism in a physiologically relevant cell line. Author SummaryEnteric adenoviruses have historically been difficult to grow in cell culture, which resulted in lack of knowledge of host factors and pathways required for infection of these medically relevant viruses. Previous studies in non-intestinal cell lines showed slow infection kinetics and generated comparatively low virus yields compared to other adenovirus types. We suggest duodenum derived HuTu80 cells as a superior cell line for studies to complement efforts using complex intestinal tissue models. We show that viral host cell factors required for virus entry differ between cell lines from distinct origins and demonstrate the importance of clathrin-mediated endocytosis.

microbiology↗

bioRxiv2021

Human AdV-20-42-42, a promising novel adenoviral vector for gene therapy and vaccine product development

Pre-existing immune responses towards adenoviral vector limit the use of a vector based on particular serotypes and its clinical applicability for gene therapy and/or vaccination. Therefore, there is a significant interest to vectorize novel adenoviral types that have low seroprevalence in the human population. Here, we describe the discovery and vectorization of a chimeric human adenovirus, which we call HAdV-20-42-42. Full genome sequencing revealed that this virus is closely related to human serotype 42, except for the penton-base which is derived from serotype 20. The HAdV-20-42-42 vector could be propagated stably to high titers on existing E1-complementing packaging cell lines. Receptor binding studies revealed that the vector utilized both CAR and CD46 as receptors for cell entry. Furthermore, the HAdV-20-42-42 vector was potent in transducing human and murine cardiovascular cells and tissues, irrespective of the presence of blood coagulation factor X. In addition, the vector did not sequester in the liver upon intravenous administration in rodents. Finally, we demonstrate that potent T-cell responses against vector-delivered antigens could be induced upon vaccination. In summary, from the data obtained we conclude that HAdV-20-42-42 provides a valuable addition to the portfolio of adenoviral vectors available to develop safe and efficacious products in the fields of gene therapy and vaccination. IMPORTANCEAdenoviral vectors are currently under investigation for a broad range of therapeutic indications in diverse fields, such as oncology and gene therapy, as well as for vaccination both for human and veterinary use. A wealth of data shows that pre-existing immune responses may limit the use of a vector. Particularly in the current climate of global pandemic, there is a need to expand the toolbox with novel adenoviral vectors for vaccine development. Our data demonstrates that we have successfully vectorized a novel adenovirus serotype with low seroprevalence. The cell transduction data and antigen-specific immune responses induced in vivo demonstrate that this vector is highly promising for the development of gene therapy and vaccine products.

immunology↗

bioRxiv2020

The structure of enteric human adenovirus 41 - a leading cause of diarrhoea in children

Human adenovirus (HAdV) types F40 and F41 are a prominent cause of diarrhea and diarrhea-associated mortality in young children worldwide. These enteric HAdVs differ strikingly in tissue tropism and pathogenicity from respiratory and ocular adenoviruses, but the structural basis for this divergence has been unknown. Here we present the first structure of an enteric HAdV - HAdV-F41 - determined by cryo-EM to a resolution of 3.8[A]. The structure reveals extensive alterations to the virion exterior as compared to non-enteric HAdVs, including a unique arrangement of capsid protein IX. The structure also provides new insights into conserved aspects of HAdV architecture such as a proposed location of protein V, which links the viral DNA to the capsid, and assembly-induced conformational changes in the penton base protein. Our findings provide the structural basis for adaptation to a fundamentally different tissue tropism of enteric HAdVs.

microbiology↗