Etude des propriétés antivirales d'un modulateur de la protéine Kinase R

Les infections virales déclenchent l'activation de différents mécanismes de l'immunité innée, la voie PKR - elF2a - GADD34 étant l'un d'entre eux. Notre étude vise à étudier les propriétés antivirales d'un inhibiteur de GADD34, la sephin1, qui bloquerait la déphosphorylation d'elF2a et ainsi prolongerait l'inhibition de la traduction des protéines virales induite par la PKR. Nous avons pour cela testé l'effet antiviral de la sephin 1 sur plusieurs virus de familles différentes en conditions in vitro ainsi que sur le virus de la myxomatose (MYXV) et le virus respiratoire syncytial humain (hRSV) en conditions in vivo. Nous avons pu mettre en évidence une activité antivirale de la sephin1 vis à vis de plusieurs virus en culture cellulaire. Les résultats in vivo obtenus ne permettent pas la mise en évidence d'un effet antiviral aux posologies testées contre le virus hRSV mais une diminution significative de l'excrétion virale est observée avec le MYXV

Evolutionary and temporal dynamics of emerging influenza D virus in Europe (2009-22).

peer reviewedInfluenza D virus (IDV) is an emerging influenza virus that was isolated for the first time in 2011 in the USA from swine with respiratory illness. Since then, IDV has been detected worldwide in different animal species, and it was also reported in humans. Molecular epidemiological studies revealed the circulation of two major clades, named D/OK and D/660. Additional divergent clades have been described but have been limited to specific geographic areas (i.e. Japan and California). In Europe, IDV was detected for the first time in France in 2012 and subsequently also in Italy, Luxembourg, Ireland, the UK, Switzerland, and Denmark. To understand the time of introduction and the evolutionary dynamics of IDV on the continent, molecular screening of bovine and swine clinical samples was carried out in different European countries, and phylogenetic analyses were performed on all available and newly generated sequences. Until recently, D/OK was the only clade detected in this area. Starting from 2019, an increase in D/660 clade detections was observed, accompanied by an increase in the overall viral genetic diversity and genetic reassortments. The time to the most recent common ancestor (tMRCA) of all existing IDV sequences was estimated as 1995-16 years before its discovery, indicating that the virus could have started its global spread in this time frame. Despite the D/OK and D/660 clades having a similar mean tMRCA (2007), the mean tMRCA for European D/OK sequences was estimated as January 2013 compared to July 2014 for European D/660 sequences. This indicated that the two clades were likely introduced on the European continent at different time points, as confirmed by virological screening findings. The mean nucleotide substitution rate of the hemagglutinin-esterase-fusion (HEF) glycoprotein segment was estimated as 1.403 × 10-3 substitutions/site/year, which is significantly higher than the one of the HEF of human influenza C virus (P < 0.0001). IDV genetic drift, the introduction of new clades on the continent, and multiple reassortment patterns shape the increasing viral diversity observed in the last years. Its elevated substitution rate, diffusion in various animal species, and the growing evidence pointing towards zoonotic potential justify continuous surveillance of this emerging influenza virus

Avian influenza viruses circulation in sub-Saharan Africa and crossing of the species barrier

Les virus influenza A, du fait de leur impact en santé animale, mais également en santé publique pouvant mener à l’émergence de graves pandémies, sont des virus actuellement sous haute surveillance. Face à leur grande variabilité génétique, mais également du fait des différents phénotypes qu’ils peuvent présenter chez l’homme et l’animal, il apparaît essentiel de mieux les connaître. Ces travaux de thèse ont été réalisés autours de deux axes complémentaires. Le premier s’est intéressé à mieux comprendre la circulation des VIA en Afrique subsaharienne, une région du monde où leur circulation semble s’être intensifiée depuis 2015. Une caractérisation moléculaire et antigénique des virus H5N1 et H9N2 détectés dans cette région, associée à des études de phylogénie, a pu ainsi être réalisée afin de mieux comprendre leur circulation et améliorer l’estimation du risque qu’ils représentent pour la santé publique. Le deuxième axe s’est, quant à lui, intéressé à la caractérisation biologique de marqueurs d’adaptation aux mammifères du complexe polymérase, en prenant comme modèle, le virus H5N8 de clade 2.3.4.4B. Ce dernier est un virus zoonotique qui s’est fait remarquer par ses capacités évolutives étonnantes et sa propagation rapide sur plusieurs continents. Des caractéristiques qui légitiment l’attention qui doit être portée à ce virus, afin de surveiller son évolution vers des génotypes plus problématiques pour la santé publique. Les résultats obtenus au cours de ces travaux de thèse tendent à confirmer une intensification récente de la circulation des VIA en Afrique subsaharienne. La co-circulation de divers sous-types, dont certains sont d’importance de santé publique, et l’absence de mesures de contrôle mises en place contre la propagation du virus H9N2, relève le niveau de risque d’émergence de nouveaux virus zoonotiques ou pandémiques en Afrique subsaharienne. Les résultats obtenus suite à la caractérisation biologique de marqueurs d’adaptation aux mammifères laissent supposer que l’association des mutations PB2 E627K et NP L136I pourrait améliorer les capacités réplicatives du virus H5N8 de clade 2.3.4.4B chez l’homme. L’ensemble de ces données permet ainsi de mieux caractériser les VIA qui circulent sur le terrain et ainsi estimer plus finement le risque zoonotique ou pandémique qu’ils représentent.Influenza A viruses, because of their impact on animal health, but also on public health, can lead to the emergence of serious pandemics and are currently under close surveillance. The PhD project was divided in two complementary parts. The first one was to understand better AIVs circulation in Sub- Saharan Africa, a world region where their circulation seems to have intensified since 2015. Molecular and antigenic characterizations of the H5N1 and H9N2 viruses detected in this region, associated with phylogeny studies, were performed in order to understand their circulation and improve the estimation of the risk they represent for public health. The second part consisted in the biological characterization of mammalian adaptation markers of the polymerase complex, using the clade 2.3.4.4B H5N8 virus as model. This virus is a zoonotic virus that has stood out for its amazing evolutionary capacities and its rapid spread over several continents. These characteristics justify the attention that must be paid to this virus, in order to monitor its evolution towards more problematic variants in terms of public health. The results obtained during this PhD work tend to confirm a recent intensification of the circulation of IAVs in sub-Saharan Africa. The co-circulation of various subtypes, some of which are of public health importance, and the absence of control measures put in place against the spread of the H9N2 virus increases the level of risk of emergence of new zoonotic or pandemic viruses in Sub-Saharan Africa. The results obtained following the biological characterization of mammalian adaptation markers suggest that the association of the PB2 E627K and NP L136I mutations could improve the clade 2.3.4.4B H5N8 virus fitness in humans. These data enable to better characterize the IAVs circulating in the field and thus to estimate more precisely the zoonotic or pandemic risk they represent

Circulation des virus influenza aviaires en Afrique subsaharienne et franchissement de la barrière d'espèce

Influenza A viruses, because of their impact on animal health, but also on public health, can lead to the emergence of serious pandemics and are currently under close surveillance. The PhD project was divided in two complementary parts. The first one was to understand better AIVs circulation in Sub- Saharan Africa, a world region where their circulation seems to have intensified since 2015. Molecular and antigenic characterizations of the H5N1 and H9N2 viruses detected in this region, associated with phylogeny studies, were performed in order to understand their circulation and improve the estimation of the risk they represent for public health. The second part consisted in the biological characterization of mammalian adaptation markers of the polymerase complex, using the clade 2.3.4.4B H5N8 virus as model. This virus is a zoonotic virus that has stood out for its amazing evolutionary capacities and its rapid spread over several continents. These characteristics justify the attention that must be paid to this virus, in order to monitor its evolution towards more problematic variants in terms of public health. The results obtained during this PhD work tend to confirm a recent intensification of the circulation of IAVs in sub-Saharan Africa. The co-circulation of various subtypes, some of which are of public health importance, and the absence of control measures put in place against the spread of the H9N2 virus increases the level of risk of emergence of new zoonotic or pandemic viruses in Sub-Saharan Africa. The results obtained following the biological characterization of mammalian adaptation markers suggest that the association of the PB2 E627K and NP L136I mutations could improve the clade 2.3.4.4B H5N8 virus fitness in humans. These data enable to better characterize the IAVs circulating in the field and thus to estimate more precisely the zoonotic or pandemic risk they represent.Les virus influenza A, du fait de leur impact en santé animale, mais également en santé publique pouvant mener à l’émergence de graves pandémies, sont des virus actuellement sous haute surveillance. Face à leur grande variabilité génétique, mais également du fait des différents phénotypes qu’ils peuvent présenter chez l’homme et l’animal, il apparaît essentiel de mieux les connaître. Ces travaux de thèse ont été réalisés autours de deux axes complémentaires. Le premier s’est intéressé à mieux comprendre la circulation des VIA en Afrique subsaharienne, une région du monde où leur circulation semble s’être intensifiée depuis 2015. Une caractérisation moléculaire et antigénique des virus H5N1 et H9N2 détectés dans cette région, associée à des études de phylogénie, a pu ainsi être réalisée afin de mieux comprendre leur circulation et améliorer l’estimation du risque qu’ils représentent pour la santé publique. Le deuxième axe s’est, quant à lui, intéressé à la caractérisation biologique de marqueurs d’adaptation aux mammifères du complexe polymérase, en prenant comme modèle, le virus H5N8 de clade 2.3.4.4B. Ce dernier est un virus zoonotique qui s’est fait remarquer par ses capacités évolutives étonnantes et sa propagation rapide sur plusieurs continents. Des caractéristiques qui légitiment l’attention qui doit être portée à ce virus, afin de surveiller son évolution vers des génotypes plus problématiques pour la santé publique. Les résultats obtenus au cours de ces travaux de thèse tendent à confirmer une intensification récente de la circulation des VIA en Afrique subsaharienne. La co-circulation de divers sous-types, dont certains sont d’importance de santé publique, et l’absence de mesures de contrôle mises en place contre la propagation du virus H9N2, relève le niveau de risque d’émergence de nouveaux virus zoonotiques ou pandémiques en Afrique subsaharienne. Les résultats obtenus suite à la caractérisation biologique de marqueurs d’adaptation aux mammifères laissent supposer que l’association des mutations PB2 E627K et NP L136I pourrait améliorer les capacités réplicatives du virus H5N8 de clade 2.3.4.4B chez l’homme. L’ensemble de ces données permet ainsi de mieux caractériser les VIA qui circulent sur le terrain et ainsi estimer plus finement le risque zoonotique ou pandémique qu’ils représentent

Household Cases Suggest That Cats Belonging to Owners with COVID-19 Have a Limited Role in Virus Transmission

International audienceSevere acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for COVID-19 and spread rapidly following its emergence in Wuhan in 2019. Although cats are, among other domestic animals, susceptible to SARS-CoV-2 infection, little is known about their epidemiological role in the dynamics of a household infection. In this study, we monitored five cats for viral shedding daily. Each cat was confined with its COVID-19 positive owners in separate households. Low loads of viral nucleic acid were found in two cats, but only one developed anti-SARS-CoV-2 antibodies, which suggests that cats have a limited role in COVID-19 epidemiology

Influenza vaccination induces autoimmunity against orexinergic neurons in a mouse model for narcolepsy

International audienceAbstract Narcolepsy with cataplexy or narcolepsy type 1 is a disabling chronic sleep disorder resulting from the destruction of orexinergic neurons in the hypothalamus. The tight association of narcolepsy with HLA-DQB1*06:02 strongly suggest an autoimmune origin to this disease. Furthermore, converging epidemiological studies have identified an increased incidence for narcolepsy in Europe following Pandemrix® vaccination against the 2009–2010 pandemic ‘influenza’ virus strain. The potential immunological link between the Pandemrix® vaccination and narcolepsy remains, however, unknown. Deciphering these mechanisms may reveal pathways potentially at play in most cases of narcolepsy. Here, we developed a mouse model allowing to track and study the T-cell response against ‘influenza’ virus haemagglutinin, which was selectively expressed in the orexinergic neurons as a new self-antigen. Pandemrix® vaccination in this mouse model resulted in hypothalamic inflammation and selective destruction of orexin-producing neurons. Further investigations on the relative contribution of T-cell subsets in this process revealed that haemagglutinin-specific CD4 T cells were necessary for the development of hypothalamic inflammation, but insufficient for killing orexinergic neurons. Conversely, haemagglutinin-specific CD8 T cells could not initiate inflammation but were the effectors of the destruction of orexinergic neurons. Additional studies revealed pathways potentially involved in the disease process. Notably, the interferon-γ pathway was proven essential, as interferon-γ-deficient CD8 T cells were unable to elicit the loss of orexinergic neurons. Our work demonstrates that an immunopathological process mimicking narcolepsy can be elicited by immune cross-reactivity between a vaccine antigen and a neuronal self-antigen. This process relies on a synergy between autoreactive CD4 and CD8 T cells for disease development. This work furthers our understanding of the mechanisms and pathways potentially involved in the development of a neurological side effect due to a vaccine and, likely, to narcolepsy in general

Risk Mapping of Influenza D Virus Occurrence in Ruminants and Swine in Togo Using a Spatial Multicriteria Decision Analysis Approach

Influenza D virus (IDV) has been identified in several continents, with serological evidence for the virus in Africa. In order to improve the sensitivity and cost–benefit of IDV surveillance in Togo, risk maps were drawn using a spatial multicriteria decision analysis (MCDA) and experts’ opinion to evaluate the relevance of sampling areas used so far. Areas at highest risk of IDV occurrence were the main cattle markets. The maps were evaluated with previous field surveillance data collected in Togo between 2017 and 2019: 1216 sera from cattle, small ruminants, and swine were screened for antibodies to IDV by hemagglutination inhibition (HI) assays. While further samples collections are needed to validate the maps, the risk maps resulting from the spatial MCDA approach generated here highlight several priority areas for IDV circulation assessment

Evaluation of the Antiviral Activity of Sephin1 Treatment and Its Consequences on eIF2α Phosphorylation in Response to Viral Infections

International audienceThe guanabenz derivative Sephin1 has recently been proposed to increase the levels of translation initiation factor 2 (eIF2α) phosphorylation by inhibiting dephosphorylation by the protein phosphatase 1—GADD34 (PPP1R15A) complex. As phosphorylation of eIF2α by protein kinase R (PKR) is a prominent cellular antiviral pathway, we evaluated the consequences of Sephin1 treatment on virus replication. Our results provide evidence that Sephin1 downregulates replication of human respiratory syncytial virus, measles virus, human adenovirus 5 virus, human enterovirus D68, human cytomegalovirus, and rabbit myxoma virus. However, Sephin1 proved to be inactive against influenza virus, as well as against Japanese encephalitis virus. Sephin1 increased the levels of phosphorylated eIF2α in cells exposed to a PKR agonist. By contrast, in virus-infected cells, the levels of phosphorylated eIF2α did not always correlate with the inhibition of virus replication by Sephin1. This work identifies Sephin1 as an antiviral molecule in cell culture against RNA, as well as DNA viruses belonging to phylogenetically distant families