Genetic Evidence for a Tacaribe Serocomplex Virus, Mexico

We isolated arenavirus RNA from white-toothed woodrats (Neotoma leucodon) captured in a region of Mexico in which woodrats are food for humans. Analyses of nucleotide and amino acid sequence data indicated that the woodrats were infected with a novel Tacaribe serocomplex virus, proposed name Real de Catorce virus

Le virus de l'immunodéficience humaine de type I détourne la matrice

HIV-1 cell-to-cell spread is thousands fold more efficient than cell-free infection; yet the nature of the infectious material transferred at the junction remains poorly documented. We found that HIV-1 T cell-associated infectivity mostly resides at the cell surface in a viral biofilm. Initially described for HTLV-1, a viral biofilm is defined as extracellular viral particles aggregated within a scaffold of extracellular matrix (ECM) components exposed at the surface of infected cells. Using a combination of microscopy techniques, we report the presence of HIV-1 biofilms at the surface of HIV-1 infected T cells (chronically infected T cells lines as well as primary CD4+ T cells infected in vitro with HIV-1 laboratory strains as well as primary isolates). Importantly, we show that CD4+ T cells isolated from HIV-1 patients produce a viral biofilm as well. We partially characterize the composition of HIV-1 biofilm in ECM components and unravel their contribution to HIV-1 transmission. We show that HIV-1 biofilm is transferred both between T cells and during dendritic-cell (DC)-mediated trans-infection and confers viral particles with an increased infectivity as compared to their cell-free counterparts. This increased infectivity is preserved in the presence of antiretroviral treatment and neutralizing antibodies. Our findings hence identify HIV-1 biofilm as a new infectious entity central for the efficiency of HIV-1 cell-to-cell transmission. This new mechanism of intercellular transmission might be shared by other viruses and will require appraisal in the design of future therapeutical strategies.La dissémination du VIH-1 par contacts cellulaires est plus efficace que sa transmission par particules virales libres. Cependant, la nature du matériel infectieux transféré à la jonction reste très mal connue. Nos travaux révèlent que l'infectivité du VIH-1 associée aux lymphocytes T est majoritairement portée à la surface cellulaire dans un biofilm viral. Initialement décrit pour le rétrovirus lymphotrope HTLV-1 (Human T-cell Leukemia Virus type-1), le biofilm viral est une colonie extracellulaire de particules virales infectieuses enchâssées dans un cocon de matrice extracellulaire (MEC). Par un panel de techniques de microscopie, nous décrivons la présence de biofilms viraux à la surface de lymphocytes T infectés par le VIH-1 (lignées chroniquement infectées, lymphocytes CD4+ primaires infectés in vitro par des souches de laboratoire et des isolats primaires, lymphocytes de patients). Nous identifions certains éléments de la MEC enrichis dans le biofilm du VIH-1 et démontrons que certains de ces composants, modulés par l'infection, favorisent la transmission du VIH-1. En effet, le biofilm viral joue un rôle clé dans la transmission directe (entre lymphocytes T) et indirecte (trans-infection) du VIH-1. De plus, le biofilm du VIH-1 confère une infectivité accrue aux particules virales, avantage préservé en présence d'antirétroviraux et d'anticorps neutralisants.L'ensemble de notre travail identifie une nouvelle entité infectieuse cruciale pour la dissémination du VIH-1 par contacts cellulaires. Ce nouveau mécanisme de transmission, potentiellement généralisable à d'autres virus, sera désormais à prendre en compte dans l'élaboration de nouvelles stratégies thérapeutiques

Stratégies de gestion des outillages lithiques au Néolithique

This paper seeks to examine and evaluate the nature of the differences between neolithic and earlier lithic assemblages. The strategies of lithic procurement, production and use are considered in a synthetic manner, following the different steps of the "chaîne opératoire". This leads to emphasize a considerable augmentation in the technical and conceptual knowledges implied all along the production of lithic tool-kits and, consequently, a different distribution of this knowledge within prehistoric societies. Therfore, the changes that can be attribued to new technical needs appear to be far less important than the changes in the socioeconomic context of production, at least in those regions where specialized production and exchanges become the norm.L'objet de cet article est de présenter la nature des différences entre les stratégies de gestion des industries néolithiques et celles des périodes antérieures. Ces stratégies sont examinées, de façon synthétique, en suivant le déroulement des chaînes opératoires, depuis l'extraction des matières premières jusqu'au rejet de l'outil. Ceci conduit à poser une augmentation parfois considérable des savoir-faire impliqués tout au long de la production lithique, qui va de pair avec une distribution profondément différente de ceux-ci au sein des sociétés préhistoriques. Ainsi, les différences entraînées par des besoins techniques nouveaux paraissent de faible impact en regard des transformations socio-économiques du contexte de production, du moins dans les régions où production spécialisée et échanges deviennent la norme.Binder Didier, Perlès Catherine, Inizan Marie-Louise, Lechevallier Monique. Stratégies de gestion des outillages lithiques au Néolithique. In: Paléo, n°2,1990. pp. 257-283

Vector competence of Aedes aegypti from New Caledonia for the four recent circulating dengue virus serotypes

International audienceIn New Caledonia (NC), Aedes aegypti is the only proven vector of dengue virus (DENV), which is the most prevalent arbovirosis in NC. Since World War II, the four DENV serotypes have circulated regularly in NC. The epidemiological profile, however, has evolved over the last ten years, with the persistence of DENV-1 circulation and the co-circulation of several DENV serotypes. The current study evaluated the ability of Ae. aegypti from NC to transmit four DENV serotypes (and two DENV-1 genotypes) isolated during recent outbreaks in NC. An Ae. aegypti F1 generation was twice independently orally challenged with each DENV strain (107 FFU/ml). Infection, dissemination and transmission rates and transmission efficiency were measured at day 7 and 14 post-exposure, as well as the quantity of infectious virus particles. Mosquito infection was observed as early as 7 days post-infection. Infection rates between 18 and 58% were measured for all DENV serotypes/genotypes tested. Although dissemination rates ranged from 78 to 100%, transmission efficiencies were low, with values not exceeding 21% at 14 days post-infection for all DENV strains. This study shows that NC Ae. aegypti are moderately competent for DENV in laboratory conditions. In link with epidemiological data, these results suggest implication of other factors in the sustained circulation of DENV-1 in New Caledonia

Séances plénières et conférences : Le « Biofilm viral », de nouvelles entités infectieuses pour un nouveau mode de transmission des virus par contact cellulaire

International audienceLa dissémination des rétrovirus lymphotropes VIH-1 et HTLV-1 implique la formation de jonctions intercellulaires viro-induites entre cellules infec- tées et cellules cibles, appelées « synapses virologiques ». Ces jonctions favorisent le transfert d’un matériel infectieux dont la nature reste mal définie. Dans le cas du HTLV-1, nous avons montré que sa transmission entre lymphocytes T met en jeu un « biofilm viral », structure infectieuse et protectrice composée de particules virales enchâssées dans un cocon de matrice extracellulaire (MEC) et de protéines de pontage, dont la pro- duction est viro-induite. Ces biofilms, produits à la surface des cellules infectées, peuvent être transmis très rapidement à la cellule cible par contact cellulaire. Lors du contact entre cellule productrice de virions et cellule cible, le « biofilm viral » (particules virales et protéines cellulaires associées) « ponte » les surfaces des deux cellules engagées et adhère très rapidement à la surface de la cellule cible. Il permet ainsi la transmission des particules virales qui fusionnent ensuite avec la membrane de la cellule cible. De fait, le « biofilm viral » est primordial pour la dissémination de HTLV-1 : son élimination de la surface de cellules infectées diminue de plus de 80 % la capacité des cellules à infecter d’autres cellules. Ainsi, le « biofilm viral », préformé à la surface des cellules infectées, représente une nouvelle entité infectieuse, essentielle pour stocker le pathogène, en concentrer le pouvoir infectieux, et permettre sa dissémination lors de contacts entre cellules. Ce type de structures, adhésives et se fractionnant au fil des contacts entre cellules, semble particulièrement adapté à la dissémination de particules virales dans les zones de haute densité cellulaire comme les ganglions lymphatiques. Plus généralement, la découverte de ce nouveau type d’entité infectieuse et de ce nouveau mode de dissémination soulève de nouvelles questions. D’autres virus, en particulier ceux qui se transmettent très efficacement par contact cellulaire, produisent-ils des structures similaires

Dengue in New Caledonia: Knowledge and Gaps

International audienceArboviruses are viruses transmitted to humans by the bite of infected mosquito vectors. Over the last decade, arbovirus circulation has increasingly been detected in New Caledonia (NC), a French island territory located in the subtropical Pacific region. Reliable epidemiological, entomological, virological and climate data have been collected in NC over the last decade. Here, we describe these data and how they inform arboviruses' epidemiological profile. We pinpoint areas which remain to be investigated to fully understand the peculiar epidemiological profile of arbovirus circulation in NC. Further, we discuss the advantages of conducting studies on arboviruses dynamics in NC. Overall, we show that conclusions drawn from observations conducted in NC may inform epidemiological risk assessments elsewhere and may be vital to guide surveillance and response, both in New Caledonia and beyond

Viral evolution sustains a dengue outbreak of enhanced severity

International audienceCompared to the previous 2013-2014 outbreak, dengue 2016-2017 outbreak in New Caledonia was characterized by an increased number of severe forms associated with hepatic presentations. In this study, we assessed the virological factors associated with this enhanced severity. Whole-genome sequences were retrieved from dengue virus (DENV)-1 strains collected in 2013-2014 and from severe and non-severe patients in 2016-2017. Fitness, hepatic tropism and cytopathogenicity of DENV 2016-2017 strains were compared to those of 2013-2014 strains using replication kinetics in the human hepatic cell line HuH7. Whole-genome sequencing identified four amino acid substitutions specific to 2016-2017 strains and absent from 2013-2014 strains. Three of these mutations occurred in predicted T cell epitopes, among which one was also a B cell epitope. Strains retrieved from severe forms did not exhibit specific genetic features. DENV strains from 2016-2017 exhibited a trend towards reduced replicative fitness and cytopathogenicity in vitro compared to strains from 2013-2014. Overall, the 2016-2017 dengue outbreak in New Caledonia was associated with a viral genetic evolution which had limited impact on DENV hepatic tropism and cytopathogenicity. These mutations, however, may have modified DENV strains antigenicity, altering the anti-DENV immune response in some patients, in turn favoring the development of severe forms

Molecular Characterization of Dengue Type 2 Outbreak in Pacific Islands Countries and Territories, 2017–2020

International audienceDengue virus (DENV) serotype-2 was detected in the South Pacific region in 2014 for the first time in 15 years. In 2016-2020, DENV-2 re-emerged in French Polynesia, Vanuatu, Wallis and Futuna, and New Caledonia, co-circulating with and later replacing DENV-1. In this context, epidemiological and molecular evolution data are paramount to decipher the diffusion route of this DENV-2 in the South Pacific region. In the current work, the E gene from 23 DENV-2 serum samples collected in Vanuatu, Fiji, Wallis and Futuna, and New Caledonia was sequenced. Both maximum likelihood and Bayesian phylogenetic analyses were performed. While all DENV-2 strains sequenced belong to the Cosmopolitan genotype, phylogenetic analysis suggests at least three different DENV-2 introductions in the South Pacific between 2017 and 2020. Strains retrieved in these Pacific Islands Countries and Territories (PICTs) in 2017-2020 are phylogenetically related, with strong phylogenetic links between strains retrieved from French PICTs. These phylogenetic data substantiate epidemiological data of the DENV-2 diffusion pattern between these countries