Outbreak of Oropouche Virus in French Guiana.

Oropouche fever is a zoonotic dengue-like syndrome caused by Oropouche virus. In August-September 2020, dengue-like syndrome developed in 41 patients in a remote rainforest village in French Guiana. By PCR or microneutralization, 23 (82.1%) of 28 tested patients were positive for Oropouche virus, documenting its emergence in French Guiana.

Epigenesis and plasticity of mouse trophoblast stem cells.

The critical role of the placenta in supporting a healthy pregnancy is mostly ensured by the extraembryonic trophoblast lineage that acts as the interface between the maternal and the foetal compartments. The diverse trophoblast cell subtypes that form the placenta originate from a single layer of stem cells that emerge from the embryo when the earliest cell fate decisions are occurring. Recent studies show that these trophoblast stem cells exhibit extensive plasticity as they are capable of differentiating down multiple pathways and are easily converted into embryonic stem cells in vitro. In this review, we discuss current knowledge of the mechanisms and control of the epigenesis of mouse trophoblast stem cells through a comparison with the corresponding mechanisms in pluripotent embryonic stem cells. To illustrate some of the more striking manifestations of the epigenetic plasticity of mouse trophoblast stem cells, we discuss them within the context of two paradigms of epigenetic regulation of gene expression: the imprinted gene expression of specific loci and the process of X-chromosome inactivation.

Detection and Diagnosis of Rift Valley Fever Virus.

Rift Valley fever virus (RVFV) is a globally important mosquito-borne virus that can also be directly transmitted via aerosolization of body fluids from infected animals. RVFV outbreaks cause mass mortality of young livestock and abortions in animals. In most severe human cases, the disease can progress to hemorrhagic fever and encephalitis, leading to death. RVF has a significant economic impact due to the loss of livestock that is a great challenge for people who depend on animals for income and food. Several vaccines are available for animal use, but none are yet licensed for use in human populations. This situation emphasizes the need to have robust and efficient diagnostic methods that can be used for early case confirmation, assessment of seroprevalence, and virus surveillance as well as vaccine efficacy evaluation. Despite the existence of different diagnostic methods for RVFV, we still have untimely reporting or underreporting of cases, probably due to lack of appropriate surveillance systems or diagnostic tools in some endemic countries. Here, we describe different methods available for detection and diagnosis of RVFV.

[Dual-use research on modified pathogens in the laboratory: What framework for what issue?] / Recherche à usage dual sur les pathogènes modifiés en laboratoire - Quel encadrement pour quels enjeux ?

Technological advances in synthetic biology have made in vitro modification, or even creation, of viruses easier and more affordable. Several research studies using synthesis of potential pandemic pathogens led to controversies in the 2010's. More recently, the hypothesis that Covid-19 pandemics could originate from a lab escape is still under debate. In France, a legislative vacuum remains concerning the synthesis of modified pathogens. Initiating a collective reflection process towards setting of a legal framework on this type of work is timely so that research continues to provide profit to society rather than hazard.

Title: Recherche à usage dual sur les pathogènes modifiés en laboratoire - Quel encadrement pour quels enjeux ? Abstract: Les avancées techniques en biologie de synthèse rendent de plus en plus accessibles la modification ou même la fabrication de virus en laboratoire. Plusieurs travaux de recherche fondés sur la synthèse de pathogènes à potentiel pandémique ont créé la polémique au cours des années 2010 et, aujourd'hui encore, l'éventualité qu'une fuite de laboratoire soit à l'origine de la pandémie de Covid-19 fait débat. En France, un vide juridique subsiste concernant la synthèse de pathogènes modifiés. Une réflexion concertée vers un encadrement légal de ce type de recherche apparaît donc nécessaire et urgent pour que la recherche continue de représenter un bénéfice, plutôt qu'un risque, pour la société.

A rapid passage through a two-active-X-chromosome state accompanies the switch of imprinted X-inactivation patterns in mouse trophoblast stem cells.

BACKGROUND: In female mice, while the presence of two-active X-chromosomes characterises pluripotency, it is not tolerated in most other cellular contexts. In particular, in the trophoblastic lineage, impairment of paternal X (X(P)) inactivation results in placental defects. RESULTS: Here, we show that Trophoblast Stem (TS) cells can undergo a complete reversal of imprinted X-inactivation without detectable change in cell-type identity. This reversal occurs through a reactivation of the X(P) leading to TS clones showing two active Xs. Intriguingly, within such clones, all the cells rapidly and homogeneously either re-inactivate the X(P) or inactivate, de novo, the X(M). CONCLUSION: This secondary non-random inactivation suggests that the two-active-X states in TS and in pluripotent contexts are epigenetically distinct. These observations also reveal a pronounced plasticity of the TS epigenome allowing TS cells to dramatically and accurately reprogram gene expression profiles. This plasticity may serve as a back-up system when X-linked mono-allelic gene expression is perturbed.