The cytoplasmic tail of the rabies virus G protein is an essential domain controlling death/survival in human neuronal cells

Poster presentation

Comparison of Atmospheric and Lithospheric Culturable Bacterial Communities from Two Dissimilar Active Volcanic Sites, Surtsey Island and Fimmvörðuháls Mountain in Iceland

This research was funded by the Icelandic Research fund (IRF, RANNÍS) (174425-051). T.Š.-T. was supported by The Danish National Research Foundation (DNRF106, to the Stellar Astrophysics Centre, Aarhus University), the AUFF Nova programme (AUFF-E-2015-FLS-9-10), the Novo Nordisk Foundation (NNF19OC0056963) and the Villum Fonden (23175 and 37435). The Europlanet 2020 Research Infrastructure TA program (18-EPN4-059) funded T.Š.-T. participation in the sampling campaign.Surface microbes are aerosolized into the atmosphere by wind and events such as dust storms and volcanic eruptions. Before they reach their deposition site, they experience stressful atmospheric conditions which preclude the successful dispersal of a large fraction of cells. In this study, our objectives were to assess and compare the atmospheric and lithospheric bacterial cultivable diversity of two geographically different Icelandic volcanic sites: the island Surtsey and the Fimmvörðuháls mountain, to predict the origin of the culturable microbes from these sites, and to select airborne candidates for further investigation. Using a combination of MALDI Biotyper analysis and partial 16S rRNA gene sequencing, a total of 1162 strains were identified, belonging to 72 species affiliated to 40 genera with potentially 26 new species. The most prevalent phyla identified were Proteobacteria and Actinobacteria. Statistical analysis showed significant differences between atmospheric and lithospheric microbial communities, with distinct communities in Surtsey’s air. By combining the air mass back trajectories and the analysis of the closest representative species of our isolates, we concluded that 85% of our isolates came from the surrounding environments and only 15% from long distances. The taxonomic proportions of the isolates were reflected by the site’s nature and location.Peer reviewe

Toll-Like Receptor 3 (TLR3) Plays a Major Role in the Formation of Rabies Virus Negri Bodies

Human neurons express the innate immune response receptor, Toll-like receptor 3 (TLR3). TLR3 levels are increased in pathological conditions such as brain virus infection. Here, we further investigated the production, cellular localisation, and function of neuronal TLR3 during neuronotropic rabies virus (RABV) infection in human neuronal cells. Following RABV infection, TLR3 is not only present in endosomes, as observed in the absence of infection, but also in detergent-resistant perinuclear inclusion bodies. As well as TLR3, these inclusion bodies contain the viral genome and viral proteins (N and P, but not G). The size and composition of inclusion bodies and the absence of a surrounding membrane, as shown by electron microscopy, suggest they correspond to the previously described Negri Bodies (NBs). NBs are not formed in the absence of TLR3, and TLR3−/− mice—in which brain tissue was less severely infected—had a better survival rate than WT mice. These observations demonstrate that TLR3 is a major molecule involved in the spatial arrangement of RABV–induced NBs and viral replication. This study shows how viruses can exploit cellular proteins and compartmentalisation for their own benefit

Polyvalent catanionic vesicles: Exploring the drug delivery mechanisms

International audienceAmong drug delivery systems, catanionic vesicles now appear as powerful candidates for pharmaceutical applications because they are relatively cheap and easy to use, thus well corresponding to industrial requirements. Using labelled vesicles made of a tricatenar catanionic surfactant, the work reported here aims at exploring the mechanisms by which internalisation into a cell occurs. The study was performed on various cell types such as phagocytic as well as non-phagocytic cells using confocal laser scanning microscopy and flow cytometry. Using various inhibitors, endocytosis and also a passive process, as probably fusion, were highlighted as interaction phenomena between catanionic vesicles and cell membranes. Finally, the interaction modelled with giant liposomes as membrane models confirmed the hypothesis of the occurrence of a fusion phenomenon between the nanovectors and cell membranes. This process highlights the potential of catanionic vesicles for a future pharmaceutical application as a universal drug delivery system

Attenuation of rabies virulence: takeover by the cytoplasmic domain of its envelope protein.

International audienceThe capacity of a rabies virus to promote neuronal survival (a signature of virulence) or death (a marker of attenuation) depends on the cellular partners recruited by the PDZ-binding site (PDZ-BS) of its envelope glycoprotein (G). Neuronal survival requires the selective association of the PDZ-BS of G with the PDZ domains of two closely related serine-threonine kinases, MAST1 and MAST2. Here, we found that a single amino acid change in the PDZ-BS triggered the apoptotic death of infected neurons and enabled G to interact with additional PDZ partners, in particular the tyrosine phosphatase PTPN4. Knockdown of PTPN4 abrogated virus-mediated apoptosis. Thus, we propose that attenuation of rabies virus requires expansion of the set of host PDZ proteins with which G interacts, which interferes with the finely tuned homeostasis required for survival of the infected neuron

Integrated analysis of whole blood oxylipin and cytokine responses after bacterial, viral, and T cell stimulation reveals new immune networks

Summary: Oxylipins are major immunomodulating mediators, yet studies of inflammation focus mainly on cytokines. Here, using a standardized whole-blood stimulation system, we characterized the oxylipin-driven inflammatory responses to various stimuli and their relationships with cytokine responses. We performed a pilot study in 25 healthy individuals using 6 different stimuli: 2 bacterial stimuli (LPS and live BCG), 2 viral stimuli (vaccine-grade poly I:C and live H1N1 attenuated influenza), an enterotoxin superantigen and a Null control. All stimuli induced a strong production of oxylipins but most importantly, bacterial, viral, and T cell immune responses show distinct oxylipin signatures. Integration of the oxylipin and cytokine responses for each condition revealed new immune networks improving our understanding of inflammation regulation. Finally, the oxylipin responses and oxylipin-cytokine networks were compared in patients with active tuberculosis or with latent infection. This revealed different responses to BCG but not LPS stimulation highlighting new regulatory pathways for further investigations