Biology subjects

Conca, D. V.

Publications and source records attributed to Conca, D. V..

3 recordsLinked to original sources

bioRxiv2024

Variant-specific interactions at the plasma membrane: Heparan sulfate's impact on SARS-CoV-2 binding kinetics

The worldwide spread of SARS-CoV-2 has been characterised by the emergence of several variants of concern (VOCs) presenting an increasing number of mutations in the viral genome. The spike glycoprotein, responsible for engaging the viral receptor ACE2, exhibits the highest density of mutations, suggesting an ongoing evolution to optimize viral entry. However, previous studies focussed on isolated molecular interactions, neglecting the intricate composition of the plasma membrane and the interplay between viral attachment factors. Our study explores the role of avidity and of the complexity of the plasma membrane composition in modulating the virus-host binding kinetics during the early stages of viral entry for the original Wuhan strain and three VOCs: Omicron BA.1, Delta, and Alpha. We employ fluorescent liposomes decorated with spike from several VOCs as virion mimics in single-particle tracking studies on native supported lipid bilayers derived from pulmonary Calu-3 cells. Our findings reveal an increase in the affinity of the multivalent bond to the cell surface for Omicron driven by an increased association rate. We show that heparan sulfate (HS), a sulfated glycosaminoglycan commonly expressed on cells plasma membrane, plays a central role in modulating the interaction with the cell surface and we observe a shift in its role from screening the interaction with ACE2 in early VOCs to an important binding factor for Omicron. This is caused by a [~]10-fold increase in Omicrons affinity to HS compared to the original Wuhan strain, as shown using atomic force microscopy-based single-molecule force spectroscopy. Our results show the importance of coreceptors, particularly HS, and membrane complexity in the modulation of the attachment in SARS-CoV-2 VOCs. We highlight a transition in the variants attachment strategy towards the use of HS as an initial docking site, which likely plays a role in shaping Omicrons tropism towards infection of the upper airways, milder symptoms, and higher transmissibility.

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↗

bioRxiv2023

Recruitment of apolipoprotein E facilitates Herpes simplex virus 1 release

Over two decades, epidemiological studies have revealed that interactions between human polymorphic apolipoprotein 4 (ApoE, isoform 4) and herpes simplex virus type 1 (HSV1) associate with higher risk of Alzheimers disease, a serious and increasing issue among elder populations worldwide. Nevertheless, little is known about the mechanisms behind ApoE-HSV1 interactions at molecular levels. Here, we investigate the effects of ApoE on the HSV1 infectious life cycle in in vitro cell experiments. Analysis of HSV1 growth curves shows that HSV1 production is promoted in presence of any of the three ApoE isoforms, with ApoE 3 or 4 demonstrating more proviral effects than ApoE 2. Quantification by qPCR reveals that the presence of ApoE 2, 3, or 4 leads to an increase of HSV1 extracellular release but unchanged levels of viral genome copies within cells or on the cell surface, indicating that virus replication, assembly, or transport to cell membrane are not affected. Further test of virus release directly demonstrates that HSV1 detachment from the cell surface is promoted by ApoE. Subsequent results reveal that ApoE is both present in purified HSV1 particles produced in ApoE-expressing cells after ultra-centrifugation and able to incorporate into HSV1 particles after purification, suggesting that harbouring ApoE may play a key role in the pro-viral effect of ApoE. Along these lines, we tested the infectious behaviour of ApoE-coated viruses and observed faster attachment kinetics and higher entry efficiencies of ApoE decorated HSV1. Our hypothesis that the association with ApoE leads to modified interactions of the virus with the cell membrane during entry and egress, was further validated in biophysical experiments. In such experiments, HSV1-membrane interaction kinetics and apparent affinity between HSV1 and native supported lipid bilayers (a plasma membrane mimic) were quantified using total internal reflection microscopy. HSV1 particles decorated with ApoE demonstrate both higher association (kon) and dissociation rate constants (koff), as well as less irreversible binding to the membrane, which is in line with the biological experiments. Overall, our results provide new insights into the roles of ApoE during HSV1 infections, which is worth to be considered when studying their involvement during Alzheimers disease development.

microbiology↗