Syndecan 4 Is Involved in Mediating HCV Entry through Interaction with Lipoviral Particle-Associated Apolipoprotein E

Hepatitis C virus (HCV) is a major cause of liver disease worldwide and HCV infection represents a major health problem. HCV associates with host lipoproteins forming host/viral hybrid complexes termed lipoviral particles. Apolipoprotein E (apoE) is a lipoprotein component that interacts with heparan sulfate proteoglycans (HSPG) to mediate hepatic lipoprotein uptake, and may likewise mediate HCV entry. We sought to define the functional regions of apoE with an aim to identify critical apoE binding partners involved in HCV infection. Using adenoviral vectors and siRNA to modulate apoE expression we show a direct correlation of apoE expression and HCV infectivity, whereas no correlation exists with viral protein expression. Mutating the HSPG binding domain (HSPG-BD) of apoE revealed key residues that are critical for mediating HCV infection. Furthermore, a novel synthetic peptide that mimics apoE's HSPG-BD directly and competitively inhibits HCV infection. Genetic knockdown of the HSPG proteins syndecan (SDC) 1 and 4 revealed that SDC4 principally mediates HCV entry. Our data demonstrate that HCV uses apoE-SDC4 interactions to enter hepatoma cells and establish infection. Targeting apoE-SDC interactions could be an alternative strategy for blocking HCV entry, a critical step in maintaining chronic HCV infection

Hepatocyte Permissiveness to Plasmodium Infection Is Conveyed by a Short and Structurally Conserved Region of the CD81 Large Extracellular Domain

Invasion of hepatocytes by Plasmodium sporozoites is a prerequisite for establishment of a malaria infection, and thus represents an attractive target for anti-malarial interventions. Still, the molecular mechanisms underlying sporozoite invasion are largely unknown. We have previously reported that the tetraspanin CD81, a known receptor for the hepatitis C virus (HCV), is required on hepatocytes for infection by sporozoites of several Plasmodium species. Here we have characterized CD81 molecular determinants required for infection of hepatocytic cells by P. yoelii sporozoites. Using CD9/CD81 chimeras, we have identified in CD81 a 21 amino acid stretch located in a domain structurally conserved in the large extracellular loop of tetraspanins, which is sufficient in an otherwise CD9 background to confer susceptibility to P. yoelii infection. By site-directed mutagenesis, we have demonstrated the key role of a solvent-exposed region around residue D137 within this domain. A mAb that requires this region for optimal binding did not block infection, in contrast to other CD81 mAbs. This study has uncovered a new functionally important region of CD81, independent of HCV E2 envelope protein binding domain, and further suggests that CD81 may not interact directly with a parasite ligand during Plasmodium infection, but instead may regulate the function of a yet unknown partner protein

EGU General Assembly 2016, held 17-22 April, 2016 in Vienna Austria, id. EPSC2016-16813

A new approach to identify contributing fractures and ambient wellbore flow in fractured and karst aquifers is presented. It is time efficient, low cost and based on a benign tracer: the dissolved oxygen (DO). The method was already applied by other scientists to test fractured crystalline rock wells. The DO method consists in elevating water DO concentration in a borehole by bubbling air at assigned water depths using a porous polypropylene tube (bubbler) connected to a compressed air tank with tubing. After the aeration, the resulting profile should be a linear increase in DO with depth due to the effects of water pressure on oxygen solubility. Any changes in the DO profile will be then observed when water flows into and through the well. DO dilution can be used to locate inflowing fractures and to define active flow zones in wells. Where there is no change in the DO profile “dead zones” in the well, where no flow is taking place, can be identified. The DO tests in this work have been carried out in the industrial area of Bari, at the experimental station of five wells drilled at the CNR-IRSA. The wells penetrate karstic limestone. Results show enhanced flow through at depths between 32 and 37 meters below the water level and connecting patterns between the studied wells. The benefits of utilizing DO as a tracer include ease of accessibility, low cost and time-efficiency as well as non-toxic nature of the tracer and no impact on flow conditions