Rift Valley Fever – epidemiological update and risk of introduction into Europe

Rift Valley fever (RVF) is a vector-borne disease transmitted by a broad spectrum of mosquito species, especially Aedes and Culex genus, to animals (domestic and wild ruminants and camels) and humans. Rift Valley fever is endemic in sub-Saharan Africa and in the Arabian Peninsula, with periodic epidemics characterised by 5–15 years of inter-epizootic periods. In the last two decades, RVF was notified in new African regions (e.g. Sahel), RVF epidemics occurred more frequently and low-level enzootic virus circulation has been demonstrated in livestock in various areas. Recent outbreaks in a French overseas department and some seropositive cases detected in Turkey, Tunisia and Libya raised the attention of the EU for a possible incursion into neighbouring countries. The movement of live animals is the most important pathway for RVF spread from the African endemic areas to North Africa and the Middle East. The movement of infected animals and infected vectors when shipped by flights, containers or road transport is considered as other plausible pathways of introduction into Europe. The overall risk of introduction of RVF into EU through the movement of infected animals is very low in all the EU regions and in all MSs (less than one epidemic every 500 years), given the strict EU animal import policy. The same level of risk of introduction in all the EU regions was estimated also considering the movement of infected vectors, with the highest level for Belgium, Greece, Malta, the Netherlands (one epidemic every 228–700 years), mainly linked to the number of connections by air and sea transports with African RVF infected countries. Although the EU territory does not seem to be directly exposed to an imminent risk of RVFV introduction, the risk of further spread into countries neighbouring the EU and the risks of possible introduction of infected vectors, suggest that EU authorities need to strengthen their surveillance and response capacities, as well as the collaboration with North African and Middle Eastern countries.info:eu-repo/semantics/publishedVersio

Etude d’un module générique de gestion de puissance dans un OS pour systèmes embarqués

Encadrée par Michel Auguin, Maher BEN JEMAAThis project was developed as part of the National Engineering Diploma in Computer Engineering. It was carried out within the Laboratory of Electronics, Antennas and Telecommunications "LEAT" of the Nice Sophia Antipolis University.The main objective was to try to find a method that can achieve a satisfactory compromise between reducing the power consumed in a system on chip and the desired level of performance. Performance is a set of criteria imposed by the client such as the time of execution of different tasks (real-time constraint for embedded systems).Ce projet a été élaboré dans le cadre de l’obtention du diplôme national d’ingénieur en Génie Informatique. Il a été réalisé au sein du Laboratoire d’Electronique, Antennes et Télécommunications « LEAT » de l’Université Nice Sophia Antipolis.L'objectif était d’essayer de trouver une méthode réalisant un compromis satisfaisant entre la réduction de la puissance consommée dans un système sur puce et le niveau de performance désiré. La performance étant un ensemble de critères imposés par le client comme le temps d’exécution des différentes tâches (contrainte du temps réel pour les systèmes embarqués)

Contribution to the development of a model recombinant vaccine for the control of the three major viral infections of ruminants, small pox, PPR and RVF, adapted to the epidemiological situation of the Maghreb countries.

L'objectif de cette thèse est le développement d'un vaccin recombinant capripoxvirus protégeant contre la variole des ruminants, la Fièvre de la Vallée du Rift (FVR) et la Peste des Petits Ruminants (PPR) comme modèle vaccinal destiné aux pays atteints par ces infections. Une première partie de ce travail a consisté en une enquête sérologique en Tunisie pour évaluer les prévalences PPR et FVR. L'enquête menée a montré une séroprévalence PPR de 7,6% et l'absence de FVR. Le risque lié à une infection par le virus de la fièvre de la vallée du Rift n'est pas nul en raison de l'identification des vecteurs compétents Culex theileri et Culex pipiens dans les zones échantillonnées. L'élaboration du vaccin capripoxvirus FVR-PPR porte sur l'expression des gènes NSmGN-FVR et H-PPR où chacune des valences est insérée dans le site de la thymidine kinase et le site d'un analogue du récepteur à l'interleukine 8 respectivement. Le vecteur choisi pour la souche vaccinale Kenya Sheeppox-1. Bien que nos travaux aient conduit à l'obtention du capripoxvirus double recombinant, ce dernier n'a pu être purifié. L'alternative a donc été d'évaluer l'effet protecteur et l'immunogénicité induits par le simple recombinant capripoxvirus- NSmGN-FVR, qui est un produit de l'étape intermédiaire dans l'élaboration du double recombinant FVR-PPR. L'effet protecteur de notre construction a été validé par deux expérimentations chez des souris Mus m. musculus MBT/Pas, avec épreuve infectieuse. Le nombre de doses administrées, les voies d'administration ont été déterminants dans cette protection justifiée par l'obtention d'anticorps neutralisants anti-FVR. L'étude de l'immunogénicité a été réalisée sur un modèle caprin sans épreuve infectieuse, une séroconversion FVR a été observée. La lymphoprolifération et le typage des sous populations lymphocytaires ont été analysés.The aim of this thesis was to develop a capripoxvirus based recombinant vaccine against ruminant pox, Rift Valley fever (RVF) and peste des petits ruminants (PPR) considered as a vaccine model for countries affected by these infections. The first part of the work consisted in a serological survey conducted in Tunisia to detect the PPR and RVF presence. A PPR seroprevalence of 7.6% has been found and no antibodies against RVF were detected. However, the risk of infection with rift valley fever virus persists since competent vectors such as Culex pipiens and Culex theileri has been identified in the sampled areas. The development of the RVF-PPR vaccine candidate is based on the NSmGN-FVR and H-PPR gene expression - where each of the genes is inserted into the thymidine kinase and the Interleukin 8 receptor analogue genes, respectively. The vector chosen is the vaccine strain Sheeppox Kenya-1. Although the double recombinant RVF-PPR has been produced, it could not be purified. The alternative was to evaluate the protection and the immunogenicity of the single recombinant capripoxvirus NSmGN-FVR, which is a product of an intermediate step of the process of the double recombinant preparation. The protection of our vaccine candidate has been performed by two mice experiments in Mus m. musculus MBT/Pas, with challenge. The number of doses, the route of administration played a key role in the protection confirmed by the presence of neutralizing anti-RVF antibodies. The study of the immunogenicity of the vaccine candidate was conducted in goats without challenge, RVF seroconversion has been shown. Lymphoproliferation studies and lymphocytes subpopulations typing have been analysed

Expression of cytokines following vaccination of goats with a recombinant capripoxvirus vaccine expressing Rift Valley fever virus proteins.

International audienceThe mosquito-borne Rift Valley fever virus (RVFV) causes severe diseases in domesticated animals including cattle, sheep, camels and goats. Capripoxviruses (CPV) are suitable vectors for multivalent vaccine development. A recombinant rKS1-based CPV expressing the gene encoding the viral glycoprotein Gn of RVFV has been shown to induce protection in mice and sheep. The aim of this study was to evaluate the immunogenicity induced by this candidate vaccine in goats, and the level of cytokines produced by RVFV-specific Th1 and Th2 lymphocytes. The results of this study suggest that Th2 mediates immunity mainly through the significant production of IL4, which, coupled with a decrease in IFN-γ, may be involved in the replication of the capripoxvirus expressing the GN of RVFV. CD4+ cells may play the role of helper cells in B cell responses and neutralizing antibody production in the anti-CPV humoral response, leading to strong immunity against RVFV

On-wafer time-domain measurement of pulse-to-pulse stability for microwave power GaN HEMT

International audienceFor the first time, on-wafer time-domain envelope measurements of pulse-to-pulse (P2P) stability are reported in this paper. In the case of a radar burst, these on-wafer measurements are performed on a 10W power GaN HEMT in S-Band by using a digital quadrature demodulation (DQD) as complex envelope extraction technique. The impact of an irregular RF pulse train on the measured P2P stability at device level is illustrated by the influence of load impedance, input power and bias conditions

Mesures temporelles sous pointes de la stabilité pulse à pulse des transistors HEMT GaN de puissance

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Système de caractérisation calibré de dispositifs non linéaires pour l’extraction cohérente des enveloppes temporelles RF et des composantes BF associées

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MBT/Pas mouse: a relevant model for the evaluation of Rift Valley fever vaccines.

International audienceCurrently, there are no worldwide licensed vaccines for Rift Valley fever (RVF) that are both safe and effective. Development and evaluation of vaccines, diagnostics and treatments depend on the availability of appropriate animal models. Animal models are also necessary to understand the basic pathobiology of infection. Here, we report the use of an inbred MBT/Pas mouse model that consistently reproduces RVF disease and serves our purpose for testing the efficacy of vaccine candidates; an attenuated Rift Valley fever virus (RVFV) and a recombinant RVFV-capripoxvirus. We show that this model is relevant for vaccine testing

First serological investigation of peste-des-petits-ruminants and Rift Valley fever in Tunisia.

International audienceThis study, carried out between September 2006 and January 2007, is the first cross-sectional serological investigation of peste-des-petits-ruminants (PPR) and Rift Valley fever (RVF) in Tunisia. The objective was to assess the potential need to develop a dual, recombinant PPR-RVF vaccine and how such a vaccine might be utilised in Tunisia. An overall PPR seroprevalence of 7.45% was determined, a finding supported by the high specificity (99.4%) and sensitivity (94.5%) of the ELISA used. On assessment of the diversity and density of mosquitoes in the sampling area, four species of RVF-vectors of the genus Aedes and Culex were identified. However, no serological evidence of RVF was found despite the use of a highly sensitive ELISA (99-100%). Larger scale investigations are underway to confirm these findings and the continuation of the emergency vaccination program against these two diseases remains valid