Sextant. Une infrastructure de données géographiques marines et littorales

Aux niveaux national et européen, en mode opérationnel ou recherche, des produits de données d'observations sont développés afin de qualifier, packager et synthétiser de façon homogène les données marines à destination des utilisateurs en aval des centres de données. L’unité IDM d’Ifremer a développé une infrastructure de données géographiques marines et littorales, appelée Sextant (http://sextant.ifremer.fr), qui permet de documenter, diffuser et promouvoir ces produits, à destination des partenaires de l’Ifremer et du grand public. Les technologies utilisées sont inscrites dans le cadre de la mise en œuvre de la Directive Inspire. La standardisation du système est un point clé dans l'intégration des partenariats en matière de gestion de données. Ainsi, répondant aux normes de l'ISO et aux standards de l'OGC, Sextant est un système interopérable avec les systèmes d’informations nationaux et internationaux. Sextant propose trois services d’accès aux données : - le catalogue de métadonnées utilise le logiciel Geonetwork conforme aux normes de l’ISO et aux recommandations d’Inspire. L’accès aux métadonnées est normalisé par le protocole Catalogue Service for the Web (CSW 2.0.2) de l’OGC. - le Geoviewer permet la visualisation des données via les protocoles Web Map Services (WMS, WMTS, NcWMS) de l’OGC. Les données sont réparties dans plusieurs services en fonction de leur thématique ou de leur localisation géographique. En fonction du format des fichiers, on utilise le service WMTS pour les gros volume d’image ou le NcWMS pour les données grillées. - le Panier permet de télécharger les données à travers les protocoles Web Feature Services (WFS) et Web Coverage Service (WCS). Si l'accès interopérable aux produits de synthèse est géré par des outils SIG sur étagère (par exemple, mapserver), l'accès aux collections d'observations nécessite des développements spécifiques. Dans le cadre de projets Européens (MyOcean, Emodnet et SeaDataNet), l’Ifremer a développé un logiciel pour la diffusion des données d’observation in-situ. Les modules implémentent plusieurs protocoles de diffusion (SOS, Opendap, WMS, WFS) pour différents formats de collection (netcdf, odv binary collection, ...). La prochaine étape au niveau de l’infrastructure Sextant va être d’améliorer l’interface pour permettre l’affichage, le filtrage et le téléchargement des collections d’observation in-situ

Zika virus infection of mature neurons from immunocompetent mice generates a disease-associated microglia and a tauopathy-like phenotype in link with a delayed interferon beta response

International audienceBackground: Zika virus (ZIKV) infection at postnatal or adult age can lead to neurological disorders associated with cognitive defects. Yet, how mature neurons respond to ZIKV remains substantially unexplored. Methods: The impact of ZIKV infection on mature neurons and microglia was analyzed at the molecular and cellular levels, in vitro using immunocompetent primary cultured neurons and microglia, and in vivo in the brain of adult immunocompetent mice following intracranial ZIKV inoculation. We have used C57BL/6 and the genetically diverse Collaborative Cross mouse strains, displaying a broad range of susceptibility to ZIKV infection, to question the correlation between the effects induced by ZIKV infection on neurons and microglia and the in vivo susceptibility to ZIKV. Results: As a result of a delayed induction of interferon beta (IFNB) expression and response, infected neurons displayed an inability to stop ZIKV replication, a trait that was further increased in neurons from susceptible mice. Alongside with an enhanced expression of ZIKV RNA, we observed in vivo, in the brain of susceptible mice, an increased level of active Iba1-expressing microglial cells occasionally engulfing neurons and displaying a gene expression profile close to the molecular signature of disease-associated microglia (DAM). In vivo as well as in vitro, only neurons and not microglial cells were identified as infected, raising the question of the mechanisms underlying microglia activation following brain ZIKV infection. Treatment of primary cultured microglia with conditioned media from ZIKV-infected neurons demonstrated that type-I interferons (IFNs-I) secreted by neurons late after infection activate non-infected microglial cells. In addition, ZIKV infection induced pathological phosphorylation of Tau (pTau) protein, a

Broad sarbecovirus neutralization by combined memory B cell antibodies to ancestral SARS-CoV-2

International audienceAntibodies play a pivotal role in protecting from SARS-CoV-2 infection, but their efficacy is challenged by the continuous emergence of viral variants. In this study, we describe two broadly neutralizing antibodies cloned from the memory B cells of a single convalescent individual after infection with ancestral SARS-CoV-2. Cv2.3194, a resilient class 1 anti-RBD antibody, remains active against Omicron sub-variants up to BA.2.86. Cv2.3132, a near pan-Sarbecovirus neutralizer, targets the heptad repeat 2 membrane proximal region. When combined, Cv2.3194 and Cv2.3132 form a complementary SARS-CoV-2 neutralizing antibody cocktail exhibiting a local dose-dependent synergy. Thus, remarkably robust neutralizing memory B cell antibodies elicited in response to ancestral SARS-CoV-2 infection can withstand viral evolution and immune escape. The cooperative effect of such antibody combination may confer a certain level of protection against the latest SARS-CoV-2 variants

A live measles-vectored COVID-19 vaccine induces strong immunity and protection from SARS-CoV-2 challenge in mice and hamsters

International audienceSeveral COVID-19 vaccines have now been deployed to tackle the SARS-CoV-2 pandemic, most of them based on messenger RNA or adenovirus vectors.The duration of protection afforded by these vaccines is unknown, as well as their capacity to protect from emerging new variants. To provide sufficient coverage for the world population, additional strategies need to be tested. The live pediatric measles vaccine (MV) is an attractive approach, given its extensive safety and efficacy history, along with its established large-scale manufacturing capacity. We develop an MV-based SARS-CoV-2 vaccine expressing the prefusion-stabilized, membrane-anchored full-length S antigen, which proves to be efficient at eliciting strong Th1-dominant T-cell responses and high neutralizing antibody titers. In both mouse and golden Syrian hamster models, these responses protect the animals from intranasal infectious challenge. Additionally, the elicited antibodies efficiently neutralize in vitro the three currently circulating variants of SARS-CoV-2

Potent human broadly SARS-CoV-2–neutralizing IgA and IgG antibodies effective against Omicron BA.1 and BA.2

International audienceMemory B-cell and antibody responses to the SARS-CoV-2 spike protein contribute to long-term immune protection against severe COVID-19, which can also be prevented by antibody-based interventions. Here, wide SARS-CoV-2 immunoprofiling in Wuhan COVID-19 convalescents combining serological, cellular, and monoclonal antibody explorations revealed humoral immunity coordination. Detailed characterization of a hundred SARS-CoV-2 spike memory B-cell monoclonal antibodies uncovered diversity in their repertoire and antiviral functions. The latter were influenced by the targeted spike region with strong Fc-dependent effectors to the S2 subunit and potent neutralizers to the receptor-binding domain. Amongst those, Cv2.1169 and Cv2.3194 antibodies cross-neutralized SARS-CoV-2 variants of concern, including Omicron BA.1 and BA.2. Cv2.1169, isolated from a mucosa-derived IgA memory B cell demonstrated potency boost as IgA dimers and therapeutic efficacy as IgG antibodies in animal models. Structural data provided mechanistic clues to Cv2.1169 potency and breadth. Thus, potent broadly neutralizing IgA antibodies elicited in mucosal tissues can stem SARS-CoV-2 infection, and Cv2.1169 and Cv2.3194 are prime candidates for COVID-19 prevention and treatment