Labib Bakkali-Kassimi

Novel Bluetongue Virus in Goats, Corsica, France, 2014

During 2000–2013, 4 genotypes of bluetongue virus (BTV) were detected in Corsica, France. At the end of 2013, a compulsory BTV-1 vaccination campaign was initiated among domestic ruminants; biological samples from goats were tested as part of a corresponding monitoring program. A BTV strain with nucleotide sequences suggestive of a novel serotype was detected.

The Encephalomyocarditis Virus

The encephalomyocarditis virus (EMCV) is a small non-enveloped single-strand RNA virus, the causative agent of not only myocarditis and encephalitis, but also neurological diseases, reproductive disorders and diabetes in many mammalian species. EMCV pathogenesis appears to be viral strain- and host-specific, and a better understanding of EMCV virulence factors is increasingly required. Indeed, EMCV is often used as a model for diabetes and viral myocarditis, and is also widely used in immunology as a double-stranded RNA stimulus in the study of Toll-like as well as cytosolic receptors. However, EMCV virulence and properties have often been neglected. Moreover, EMCV is able to infect humans albeit with a low morbidity. Progress on xenografts, such as pig heart transplantation in humans, has raised safety concerns that need to be explored. In this review we will highlight the biology of EMCV and all known and potential virulence factors.

Co-circulation of bluetongue and epizootic haemorrhagic disease viruses in cattle in Reunion Island

Bluetongue virus (BTV) and epizootic haemorrhagic disease virus (EHDV) in deer have already been isolated in Reunion Island and have caused more or less severe clinical signs in cattle (EHDV) or in sheep (BTV), as observed in 2003. In January 2009, cattle in Reunion Island showed clinical signs suggesting infection by one or the other of these arboviral diseases. A study was set up to determine the etiology of the disease. Analysis by reverse transcriptase-polymerase chain reaction (RT-PCR) performed on blood samples from 116 cattle from different districts of the island detected the presence of the EHDV genome in 106 samples and, in 5 of them, the simultaneous occurrence of BTV and EHDV. One strain of EHDV (7 isolates) and one of BTV were isolated in embryonated eggs and a BHK-21 cell culture. Group and subgroup primer-pairs were designed on the segment 2 sequences available in GenBank to identify and type the EHDV strains. Phylogenetic analysis of the genomic segment 2 (encoding the VP2 serotype-specific protein) of the isolates confirmed the serotypes of these two orbiviruses as BTV-2 and EHDV-6 and allowed them to be compared with previously isolated strains.

Colostral antibody induced interference of inactivated bluetongue serotype-8 vaccines in calves

Since its introduction into northern Europe in 2006, bluetongue has become a major threat to animal health. While the efficacy of commercial vaccines has been clearly demonstrated in livestock, little is known regarding the effect of maternal immunity on vaccinal efficacy. Here, we have investigated the duration and amplitude of colostral antibody-induced immunity in calves born to dams vaccinated against bluetongue virus serotype 8 (BTV-8) and the extent of colostral antibody-induced interference of vaccination in these calves. Twenty-two calf-cow pairs were included in this survey. The median age at which calves became seronegative for BTV was 84 and 112 days as assayed by seroneutralisation test (SNT) and VP7 BTV competitive ELISA (cELISA), respectively. At the mean age of 118 days, 13/22 calves were immunized with inactivated BTV-8 vaccine. In most calves vaccination elicited a weak immune response, with seroconversion in only 3/13 calves. The amplitude of the humoral response to vaccination was inversely proportional to the maternal antibody level prior to vaccination. Thus, the lack of response was attributed to the persistence of virus-specific colostral antibodies that interfered with the induction of the immune response. These data suggest that the recommended age for vaccination of calves born to vaccinated dams needs to be adjusted in order to optimize vaccinal efficacy.

Encephalomyocarditis virus may use different pathways to initiate infection of primary human cardiomyocytes

Encephalomyocarditis virus (EMCV) can infect a wide range of vertebrate species including swine and non-human primates, but few data are available for humans. We therefore wanted to gain further insight into the mechanisms involved in EMCV infection of human cells. For this purpose, we analyzed the permissiveness of primary human cardiomyocytes towards two strains of EMCV; a pig myocardial strain (B279/95) and a rat strain (1086C). In this study, we show that both strains productively infect primary human cardiomyocytes and induce complete cytolysis. Binding and infection inhibition experiments indicated that attachment and infection are independent of sialic acid and heparan sulfate for B279/95 and dependent for 1086C. Sequence comparison between the two strains and three-dimensional analysis of the capsid revealed that six of the seven variable residues are surface-exposed, suggesting a role for these amino acids in binding. Moreover, analysis of variants isolated from the 1086C strain revealed the importance of lysine 231 of VP1 in the attachment of EMCV to cell-surface sialic acid residues. Together, these results show a potential for EMCV strains to use at least two different binding possibilities to initiate infection and provide new insights into the mechanisms involved in primary human cell recognition by EMCV.

A canine adenovirus type 2 vaccine vector confers protection against foot-and-mouth disease in guinea pigs

Vaccination is a key element in the control of foot-and-mouth disease (FMD). The majority of the antigenic sites that induce protective immune responses are localized on the FMD virus (FMDV) capsid that is formed by four virus-encoded structural proteins, VP1 to VP4. In the present study, recombinant canine adenovirus type 2 (CAV2)-based FMD vaccines, Cav-P1/3C R° and Cav-VP1 R°, respectively expressing the structural P1 precursor protein along with the non-structural 3C protein or expressing the structural VP1 protein of the FMDV strain O/FRA/1/2001, were evaluated as novel vaccines against FMD. A strong humoral immune response was elicited in guinea pigs (GP) following immunization with Cav-P1/3C R°, while administration of Cav-VP1 R° did not induce a satisfying antibody response in GP or mice. GP were then used as an experimental model for the determination of the protection afforded by the Cav-P1/3C R° vaccine against challenge with the FMDV strain O1 Manisa/Turkey/1969. The Cav-P1/3C R° vaccine protected GP from generalized FMD to a similar extent as a high potency double-oil emulsion O1 Manisa vaccine. The results of the present study show that CAV2-based vector vaccines can express immunogenic FMDV antigens and offer protection against generalized FMD in GP. This suggest that Cav-P1/3C R° FMDV vaccine may protect natural host species from FMD. In combination with an appropriate diagnostic test, the Cav-P1/3C R° FMDV vaccine may also serve as a marker vaccine to differentiate vaccinated from infected animals.

Reconstructing the evolutionary history of pandemic foot-and-mouth disease viruses: the impact of recombination within the emerging O/ME-SA/Ind-2001 lineage

Foot-and-mouth disease (FMD) is a highly contagious disease of livestock affecting animal production and trade throughout Asia and Africa. Understanding FMD virus (FMDV) global movements and evolution can help to reconstruct the disease spread between endemic regions and predict the risks of incursion into FMD-free countries. Global expansion of a single FMDV lineage is rare but can result in severe economic consequences. Using extensive sequence data we have reconstructed the global space-time transmission history of the O/ME-SA/Ind-2001 lineage (which normally circulates in the Indian sub-continent) providing evidence of at least 15 independent escapes during 2013–2017 that have led to outbreaks in North Africa, the Middle East, Southeast Asia, the Far East and the FMD-free islands of Mauritius. We demonstrated that sequence heterogeneity of this emerging FMDV lineage is accommodated within two co-evolving divergent sublineages and that recombination by exchange of capsid-coding sequences can impact upon the reconstructed evolutionary histories. Thus, we recommend that only sequences encoding the outer capsid proteins should be used for broad-scale phylogeographical reconstruction. These data emphasise the importance of the Indian subcontinent as a source of FMDV that can spread across large distances and illustrates the impact of FMDV genome recombination on FMDV molecular epidemiology.

Émergence et ré-émergence de deux dangers sanitaires de catégorie 1 en France (FCO) et à Maurice (FA)

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.