Unpublished conference/Abstract (Scientific congresses and symposiums)
Anti-Schmallenberg virus activities of type I/III interferons-induced Mx1 GTPases from different mammalian species
Bayrou, Calixte; Van Laere, Anne-Sophie; Dam Van, Phai et al.
2020First On-Line ECBHM Residents' session
 

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Keywords :
Schmallenberg virus; Mx protein; Antiviral molecule
Abstract :
[en] • Objectives Type I/ III interferons provide powerful and universal innate intracellular defense mechanisms against viruses. Among the antiviral effectors induced, Mx proteins of some species appear as key components of antiviral defense. The most studied isoform, the human MxA protein, is known as the “Swiss army knife” of the antiviral response due to its ability to inhibit the cellular amplification of numerous viruses belonging to, at least, 12 different families. The bovine counterpart (the bovine Mx1 protein, BoMx1) has been shown to impair the amplification of 5 different viral family members. The Schmallenberg virus (SBV) belongs to the family Peribunyaviridae and was described for the first time in 2011. After having emerged in Northern Europe, it rapidly spread across the continent causing limited or no symptoms in adult ruminants but severe malformations in a small proportion of in utero infected fetuses. The objective of this study was to look for a cause of the ruminant sensitivity to the SBV infection in comparison to other mammal species. The question was: could the ruminant sensitivity be linked to a lack of antiviral Mx1 activity against the SBV? To answer this question, four different Mx1 isoforms originated from different mammals were studied in vitro. • Materials and methods The study was conducted in cell culture-based conditions. A lipid complex (Lipofectamine® 3000 Transfection reagent kit) transfection model was used to transiently express the Mx1 protein of four different species (the bovine, canine, equine and porcine isoforms) and compare their antiviral activities. After the transfected cells being infected with the SBV, the amount of Mx1 protein and nucleoprotein (NP) of the virus was measured using the fluorescent-activated cell sorting (FACS) technology. Human embryonic kidney cells (HEK-293T) were transfected with expression plasmids designed to express the different Mx1 isoforms tagged with the V5 epitope which was flanked on the N-terminal extremity of each Mx1 protein. The presence of the V5 epitope allowed an absolute standardization of the detection of the different V5-Mx1 isoforms. After a 24h incubation post-transfection, the cells were infected with the SBV (SBV-BH80/11-4) and cell fixation was realized after 5 hours of viral amplification. The immunolabelling was achieved using, on the one hand, a phycoerythrin (PE) conjugated monoclonal antibody targeting the V5 epitope allowing the Mx1 protein detection, and, on the other hand, a primary mouse monoclonal antibody targeting the SBV nucleoprotein associated with a goat anti-mouse IgG polyclonal antibody conjugated to the fluorescein isothiocyanate (FITC) fluorochrome. The results expressed the mean intensity of 3 independent assay (one assay comprising 3 wells for each condition and 100,000 cells analyzed per well). The statistical analysis was performed by analysis of variance (ANOVA). • Results All the tested Mx1 protein isoforms showed an antiviral effect. Indeed, in a same well, the percentage of NP expressing cells was significantly lower in the V5-Mx1 positive population than in the V5-Mx1 negative population. Among the different Mx isoforms, the antiviral effect of the canine Mx1 protein was significantly less pronounced. In the conditions of this experiment a clear dose-dependent effect was seen: an increase in the Mx1-associated fluorescence intensity was correlated with a reduction of the number of NP positive cells until an almost complete absence of the NP signal in the cells with the highest Mx fluorescence values. • Conclusions The bovine species sensitivity to the SBV infection is not linked to a lack of antiviral activity of the bovine Mx1 protein against the virus. The experiment corroborates the results showing that the Mx1 proteins have been selected during evolution to efficiently inhibits the amplification of a large diversity of viruses including the Peribunyaviridae family. The dose-dependent effect we herein described could reflect an unknown specific mechanism of the SBV inhibition by the Mx1 protein.
Research center :
FARAH - Fundamental and Applied Research for Animals and Health - ULiège
Disciplines :
Veterinary medicine & animal health
Author, co-author :
Bayrou, Calixte ;  Université de Liège - ULiège > Département clinique des animaux de production (DCP) > Département clinique des animaux de production (DCP)
Van Laere, Anne-Sophie  ;  Université de Liège - ULiège > Département de morphologie et pathologie (DMP) > Pathologie spéciale et autopsies
Dam Van, Phai;  Vietnam National University of Agriculture - VNUA > Department of Veterinary Internal Medicine - Diagnostics - Pharmacology-Toxicology > Bovine clinic
Garigliany, Mutien-Marie  ;  Université de Liège - ULiège > Département de morphologie et pathologie (DMP) > Pathologie générale et autopsies
Desmecht, Daniel ;  Université de Liège - ULiège > Département de morphologie et pathologie (DMP) > Pathologie spéciale et autopsies
Language :
English
Title :
Anti-Schmallenberg virus activities of type I/III interferons-induced Mx1 GTPases from different mammalian species
Publication date :
29 September 2020
Event name :
First On-Line ECBHM Residents' session
Event date :
29 Septembre 2020
Audience :
International
Available on ORBi :
since 11 March 2021

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