Emergence of bluetongue virus serotype 4 in mainland France in 2017

Le virus de la fièvre catarrhale ovine est présent en Europe depuis la fin des années 1990, impliquant différents sérotypes. La présence du sérotype 4 a notamment été plusieurs fois rapportée dans différents pays du bassin méditerranéen ces vingt dernières années, mais n’avait jamais été détectée en France continentale. En novembre 2017, un veau âgé de 15 jours et provenant de Haute Savoie a été détecté positif pour le BTV-4 par RT-PCR en temps réel (rtRT-PCR). Le séquençage du génome a permis de montrer une proche parenté entre cette souche et la souche BTV-4 impliquée dans plusieurs épizooties dans la péninsule balkanique (2013), en Italie (2014) et en Corse (2016 et 2017). Il est probable que le BTV-4 a été introduit en France continentale par l’importation d’animaux corses infectés. En juin 2018, 84 foyers de BTV-4 ont été confirmés en France métropolitaine.Bluetongue virus is present in Europe since the end of the 1990’s involving different serotypes. The presence of serotype 4 has been reported several times and in different countries of the Mediterranean basin in the last 20 years, but had never been reported in mainland France. In November 2017, a 15-days-old calf born in Haute-Savoie was detected rtRT-PCR BTV-4 positive. Whole genome sequencing showed that this strain was closely related to BTV-4 strains involved in a large BT outbreak in the Balkan Peninsula (2013), in Italy (2014) and in Corsica (2016 and 2017). It is likely that BTV-4 has been introduced in mainland France by importation of Corsican infected animals. Currently, 84 BTV-4 outbreaks have been confirmed in mainland France

Likely introduction date of Schmallenberg virus in two french departments using serological studies in cattle

Monthly serological surveys between August 2011 and April 2012 were performed among cattle population from Manche and Meurthe-et-Moselle departments. First positive results were observed in October 2011 for both departments, with respectively 12,7 and 55,6% SBV serological prevalences. Those rates increased quickly to reach very high levels from the end of 2011. Likely introduction date of SBV in France may be situated in the second half of September or during the first days of October 2011.Une enquête de séroprévalence individuelle vis-à-vis du virus Schmallenberg (SBV) est menée entre les mois d’août 2011 et avril 2012 dans la population bovine des départements de la Manche et de la Meurthe-et-Moselle. Une séropositivité est observée à partir du mois d’octobre 2011 dans les deux départements, avec des prévalences respectives de 12,7 et 55,6%. Ces taux augmentent rapidement les mois suivants pour atteindre des prévalences élevées. Comptetenu de la position géographique de ces départements et des connaissances actuelles sur le SBV, l’introduction présumée du virus en France est située vers la fin septembre-début octobre 2011

Strong protection induced by an experimental DIVA subunit vaccine against bluetongue virus serotype 8 in cattle

AbstractBluetongue virus (BTV) infections in ruminants pose a permanent agricultural threat since new serotypes are constantly emerging in new locations. Clinical disease is mainly observed in sheep, but cattle were unusually affected during an outbreak of BTV seroype 8 (BTV-8) in Europe. We previously developed an experimental vaccine based on recombinant viral protein 2 (VP2) of BTV-8 and non-structural proteins 1 (NS1) and NS2 of BTV-2, mixed with an immunostimulating complex (ISCOM)–matrix adjuvant. We demonstrated that bovine immune responses induced by this vaccine were as good or superior to those induced by a classic commercial inactivated vaccine. In this study, we evaluated the protective efficacy of the experimental vaccine in cattle and, based on the detection of VP7 antibodies, assessed its DIVA compliancy following virus challenge. Two groups of BTV-seronegative calves were subcutaneously immunized twice at a 3-week interval with the subunit vaccine (n=6) or with adjuvant alone (n=6). Following BTV-8 challenge 3 weeks after second immunization, controls developed viremia and fever associated with other mild clinical signs of bluetongue disease, whereas vaccinated animals were clinically and virologically protected. The vaccine-induced protection was likely mediated by high virus-neutralizing antibody titers directed against VP2 and perhaps by cellular responses to NS1 and NS2. T lymphocyte responses were cross-reactive between BTV-2 and BTV-8, suggesting that NS1 and NS2 may provide the basis of an adaptable vaccine that can be varied by using VP2 of different serotypes. The detection of different levels of VP7 antibodies in vaccinated animals and controls after challenge suggested a compliancy between the vaccine and the DIVA companion test. This BTV subunit vaccine is a promising candidate that should be further evaluated and developed to protect against different serotypes

Bluetongue in Belgium, 2006

Bluetongue has emerged recently in Belgium. A bluetongue virus strain was isolated and characterized as serotype 8. Two new real-time reverse transcription–quantitative PCRs (RT-qPCRs) that amplified 2 different segments of bluetongue virus detected this exotic strain. These 2 RT-qPCRs detected infection earlier than a competitive ELISA for antibody detection

Emergence and re-emergence of two major diseases in France (bluetongue) and in Mauritius (foot-and-mouth)

L’émergence en France continentale de la fièvre catarrhale ovine (FCO) causée en 2006 par le virus de sérotype 8 (BTV-8) puis en 2007, par le virus de sérotype 1 (BTV-1) a constitué une surprise totale. Fin 2012, six ans après l’introduction de la FCO, la France a été déclarée indemne de cette maladie. Pourtant, fin août 2015, le BTV-8 a fait sa réapparition dans le centre de la France. En 2016 notre laboratoire a isolé à nouveau ce virus. En Corse, un virus de sérotype 4 (BTV-4) fut identifié le 1er décembre 2016 à partir de prélèvements de moutons. D’autre part, en 2016, nous avons identifié un virus de la fièvre aphteuse de sérotype O à Maurice. Cette présentation décrira les conditions de détection de ces virus ainsi que les résultats des analyses phylogénétiques.The emergence of Bluetongue (BT) in continental France (caused by virus of serotype 8 (BTV-8) in 2006 and virus of serotype 1 (BTV-1) in 2007) was a total surprise. End of 2012, six years after the introduction of BT, France was declared free from this disease. However, at the end of August 2015, the BTV-8 made its reappearance in the center of France. In 2016, our laboratory re-isolated this virus. In Corsica, a virus of serotype 4 was identified on 1st December 2016 from sheep samples. On another hand, in 2016, we identified a virus of Foot-and-Mouth disease serotype O in Mauritius. This presentation will describe the conditions of the detection of these viruses as well as the results of phylogenetic analyzes

Schmallenberg virus experimental infection of sheep

International audienceSince late 2011, a novel orthobunyavirus, named Schmallenberg virus (SBV), has been implicated in many cases of severely malformed bovine and ovine offspring in Europe. In adult cattle, SBV is known to cause a mild transient disease; clinical signs include short febrile episodes, decreased milk production and diarrhoea for a few days. However, the knowledge about clinical signs and pathogenesis in adult sheep is limited. In the present study, adult sheep of European domestic breeds were inoculated with SBV either as cell culture grown virus or as virus with no history of passage in cell cultures. Various experimental set-ups were used. Sampling included blood collection at different time points during the experimental period and selected organ material at autopsy. Data from this study showed, that the RNAemic period in sheep was as short as reported for cattle; viral genome was detectable for about 3-5 days by real-time RT-PCR. In total, 13 out of 30 inoculated sheep became RNAemic, with the highest viral load in animals inoculated with virus from low cell culture passaged or the animal passaged material. Contact animals remained negative throughout the study. One RNAemic sheep showed diarrhoea for several days, but fever was not recorded in any of the animals. Antibodies were first detectable 10-14 days post inoculation. Viral RNA was detectable in spleen and lymph nodes up to day 44 post inoculation. In conclusion, as described for cattle, SBV-infection in adult sheep predominantly results in subclinical infection, transient RNAemia and a specific antibody response. Maintenance of viral RNA in the lymphoreticular system is observed for an extended period