References of "Gillet, Laurent"
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See detailCryopreservation of chicken primordial germ cells by vitrification and slow-freezing: a comparative study
Tonus, Céline ULg; Connan, Delphine ULg; Waroux, Olivier ULg et al

in Theriogenology (2017), 88

In the present study, we compare a classical slow freezing method and an aseptic vitrification technique to cryopreserve a stable Primordial Gem Cells (PGCs) line issued from the Ardennaise chicken breed ... [more ▼]

In the present study, we compare a classical slow freezing method and an aseptic vitrification technique to cryopreserve a stable Primordial Gem Cells (PGCs) line issued from the Ardennaise chicken breed. Viability immediately after warming was close to 80% and did not differ between the two cryopreservation methods. Proliferation tended to be slower for both cryopreservation methods compared to controls, but the difference was significant only for vitrification. No difference was found between the two methods after flow cytometry analysis of SSEA-1 expression and RT-PCR on several factors related to PGCs phenotype. After one week in culture, all cryopreserved cells reached controls main morphological and expanding (viability/proliferation) features. However, slow freezing generated more unwanted cells clusters than vitrification. After injection of the PGCs into recipient embryos, vitrified PGCs showed a clear, yet not significant, tendency to colonize the gonad at a higher rate than slow frozen PGCs. Slow freezing in cryovials remains simple, inexpensive and less technically demanding than vitrification. Nevertheless, the intrinsic advantages of our aseptic vitrification method and the present study suggest that this should be considered as safer than classical slow freezing for cryopreserving chicken PGCs. [less ▲]

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See detailLung resident eosinophils represent a distinct cell subset with homeostatic functions
Mesnil, Claire ULg; Raulier, Stéfanie ULg; Paulissen, Geneviève et al

Conference (2016, October 21)

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See detailNo Evidence of Herpesvirus Infection in West Highland Terriers with Canine Idiopathic Pulmonary Fibrosis
Roels, Elodie ULg; Dourcy, Mickael ULg; Holopainen, S. et al

in Veterinary Pathology (2016)

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See detailLong term-cultured and cryopreserved primordial germ cells from various chicken breeds retain high proliferative potential and gonadal colonisation competency
Tonus, Céline ULg; Cloquette, Karine; Ectors, Fabien ULg et al

in Reproduction, Fertility and Development (2016), 28(5), 628-639

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See detailDeletion of Murid Herpesvirus 4 ORF63 Affects the Trafficking of Incoming Capsids toward the Nucleus.
Latif, Muhammad Bilal ULg; Machiels, Bénédicte ULg; Xiao, Xue ULg et al

in Journal of virology (2016), 90(5), 2455-72

Gammaherpesviruses are important human and animal pathogens. Despite the fact that they display the classical architecture of herpesviruses, the function of most of their structural proteins is still ... [more ▼]

Gammaherpesviruses are important human and animal pathogens. Despite the fact that they display the classical architecture of herpesviruses, the function of most of their structural proteins is still poorly defined. This is especially true for tegument proteins. Interestingly, a potential role in immune evasion has recently been proposed for the tegument protein encoded by Kaposi's sarcoma-associated herpesvirus open reading frame 63 (ORF63). To gain insight about the roles of ORF63 in the life cycle of a gammaherpesvirus, we generated null mutations in the ORF63 gene of murid herpesvirus 4 (MuHV-4). We showed that disruption of ORF63 was associated with a severe MuHV-4 growth deficit both in vitro and in vivo. The latter deficit was mainly associated with a defect of replication in the lung but did not affect the establishment of latency in the spleen. From a functional point of view, inhibition of caspase-1 or the inflammasome did not restore the growth of the ORF63-deficient mutant, suggesting that the observed deficit was not associated with the immune evasion mechanism identified previously. Moreover, this growth deficit was also not associated with a defect in virion egress from the infected cells. In contrast, it appeared that MuHV-4 ORF63-deficient mutants failed to address most of their capsids to the nucleus during entry into the host cell, suggesting that ORF63 plays a role in capsid movement. In the future, ORF63 could therefore be considered a target to block gammaherpesvirus infection at a very early stage of the infection. IMPORTANCE: The important diseases caused by gammaherpesviruses in human and animal populations justify a better understanding of their life cycle. In particular, the role of most of their tegument proteins is still largely unknown. In this study, we used murid herpesvirus 4, a gammaherpesvirus infecting mice, to decipher the role of the protein encoded by the viral ORF63 gene. We showed that the absence of this protein is associated with a severe growth deficit both in vitro and in vivo that was mainly due to impaired migration of viral capsids toward the nucleus during entry. Together, our results provide new insights about the life cycle of gammaherpesviruses and could allow the development of new antiviral strategies aimed at blocking gammaherpesvirus infection at the very early stages. [less ▲]

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See detailStructural Proteomics of Herpesviruses.
Leroy, Baptiste; Gillet, Laurent ULg; Vanderplasschen, Alain ULg et al

in Viruses (2016), 8(2),

Herpesviruses are highly prevalent viruses associated with numerous pathologies both in animal and human populations. Until now, most of the strategies used to prevent or to cure these infections have ... [more ▼]

Herpesviruses are highly prevalent viruses associated with numerous pathologies both in animal and human populations. Until now, most of the strategies used to prevent or to cure these infections have been unsuccessful because these viruses have developed numerous immune evasion mechanisms. Therefore, a better understanding of their complex lifecycle is needed. In particular, while the genome of numerous herpesviruses has been sequenced, the exact composition of virions remains unknown for most of them. Mass spectrometry has recently emerged as a central method and has permitted fundamental discoveries in virology. Here, we review mass spectrometry-based approaches that have recently allowed a better understanding of the composition of the herpesvirus virion. In particular, we describe strategies commonly used for proper sample preparation and fractionation to allow protein localization inside the particle but also to avoid contamination by nonstructural proteins. A collection of other important data regarding post-translational modifications or the relative abundance of structural proteins is also described. This review also discusses the poorly studied importance of host proteins in herpesvirus structural proteins and the necessity to develop a quantitative workflow to better understand the dynamics of the structural proteome. In the future, we hope that this collaborative effort will assist in the development of new strategies to fight these infections. [less ▲]

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See detailBovine Herpesvirus 4 Modulates Its beta-1,6-N-Acetylglucosaminyltransferase Activity through Alternative Splicing.
Lété, Céline ULg; Markine-Goriaynoff, Nicolas; Machiels, Bénédicte ULg et al

in Journal of virology (2016), 90(4), 2039-51

Carbohydrates play major roles in host-virus interactions. It is therefore not surprising that, during coevolution with their hosts, viruses have developed sophisticated mechanisms to hijack for their ... [more ▼]

Carbohydrates play major roles in host-virus interactions. It is therefore not surprising that, during coevolution with their hosts, viruses have developed sophisticated mechanisms to hijack for their profit different pathways of glycan synthesis. Thus, the Bo17 gene of Bovine herpesvirus 4 (BoHV-4) encodes a homologue of the cellular core 2 protein beta-1,6-N-acetylglucosaminyltransferase-mucin type (C2GnT-M), which is a key player for the synthesis of complex O-glycans. Surprisingly, we show in this study that, as opposed to what is observed for the cellular enzyme, two different mRNAs are encoded by the Bo17 gene of all available BoHV-4 strains. While the first one corresponds to the entire coding sequence of the Bo17 gene, the second results from the splicing of a 138-bp intron encoding critical residues of the enzyme. Antibodies generated against the Bo17 C terminus showed that the two forms of Bo17 are expressed in BoHV-4 infected cells, but enzymatic assays revealed that the spliced form is not active. In order to reveal the function of these two forms, we then generated recombinant strains expressing only the long or the short form of Bo17. Although we did not highlight replication differences between these strains, glycomic analyses and lectin neutralization assays confirmed that the splicing of the Bo17 gene gives the potential to BoHV-4 to fine-tune the global level of core 2 branching activity in the infected cell. Altogether, these results suggest the existence of new mechanisms to regulate the activity of glycosyltransferases from the Golgi apparatus. IMPORTANCE: Viruses are masters of adaptation that hijack cellular pathways to allow their growth. Glycans play a central role in many biological processes, and several studies have highlighted mechanisms by which viruses can affect glycosylation. Glycan synthesis is a nontemplate process regulated by the availability of key glycosyltransferases. Interestingly, bovine herpesvirus 4 encodes one such enzyme which is a key enzyme for the synthesis of complex O-glycans. In this study, we show that, in contrast to cellular homologues, this virus has evolved to alternatively express two proteins from this gene. While the first one is enzymatically active, the second results from the alternative splicing of the region encoding the catalytic site of the enzyme. We postulate that this regulatory mechanism could allow the virus to modulate the synthesis of some particular glycans for function at the location and/or the moment of infection. [less ▲]

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See detailLong term culture, cryopreservation and genetic modification of chicken primordial germ cells
Tonus, Céline ULg; Garcia Gil, Francisco José ULg; Cloquette, Karine et al

Poster (2015, October 16)

Avian primordial germ cells (PGCs) are precursor of gametes and appear during early stages of embryonic development. Under appropriate culture conditions, these cells can keep their germ cells properties ... [more ▼]

Avian primordial germ cells (PGCs) are precursor of gametes and appear during early stages of embryonic development. Under appropriate culture conditions, these cells can keep their germ cells properties in vitro and are foreseen as promising tools for developing efficient avian genetic engineering and preservation of germplasm. We propose original methods that allow long term expansion, efficient cryopreservation and genetic modification of primary cultures of undifferentiated PGCs. PGCs are collected from embryonic blood during their migratory period and grown in cell-culture insert in the presence of feeder cells (BRL). This physically separated co-culture system along with selective culture medium promoted emergence, selection and proliferation of PGCs lines. Forty percent of blood samples gave rise to lines originating from three commercial layer and two Belgian endangered breeds. PGCs lines were characterized for the expression of the stem cells and PGCs marker SSEA-1 by FACS. RT-PCR confirmed expression of germ-line specific markers (CVH, CDH, DAZL), pluripotency markers (cPouV, cSox2, cNanog), telomerase and CXCR4 receptor. All lines were male although isolated from pooled male and female blood samples. Two cryopreservation methods were developed based upon slow-freezing and aseptic vitrification. Both have shown a similar effectiveness in allowing storage without phenotype drift. Stably expressing lines were obtained by Lipofectamine® mediated transfection of a GFP plasmid. PGCs were subsequently injected in recipient embryos. Persistence of exogenous PGCs in the developing gonad of recipient embryos confirmed that PGCs retain their gonadal colonisation ability, both after long-term culture and after cryopreservation. [less ▲]

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See detailCanine idopathic pulmonary fibrosis is not associated with herpes virus infection
Roels, Elodie ULg; Dourcy, Mickael ULg; Holopainen, S. et al

Poster (2015, October)

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See detailThe Interferon-Inducible Mouse Apolipoprotein L9 and Prohibitins Cooperate to Restrict Theiler's Virus Replication.
Kreit, Marguerite; Vertommen, Didier; Gillet, Laurent ULg et al

in PloS one (2015), 10(7), 0133190

Apolipoprotein L9b (Apol9b) is an interferon-stimulated gene (ISG) that has antiviral activity and is weakly expressed in primary mouse neurons as compared to other cell types. Here, we show that both ... [more ▼]

Apolipoprotein L9b (Apol9b) is an interferon-stimulated gene (ISG) that has antiviral activity and is weakly expressed in primary mouse neurons as compared to other cell types. Here, we show that both Apol9 isoforms (Apol9b and Apol9a) inhibit replication of Theiler's murine encephalomyelitis virus (TMEV) but not replication of vesicular stomatitis virus (VSV), Murid herpesvirus-4 (MuHV-4), or infection by a lentiviral vector. Apol9 genes are strongly expressed in mouse liver and, to a lesser extent, in pancreas, adipose tissue and intestine. Their expression is increased by type I interferon and viral infection. In contrast to genuine apolipoproteins that are involved in lipid transport, ApoL9 has an intracytoplasmic localization and does not seem to be secreted. The cytoplasmic localization of ApoL9 is in line with the observation that ApoL9 inhibits the replication step of TMEV infection. In contrast to human ApoL6, ApoL9 did not sensitize cells to apoptosis, in spite of the presence of a conserved putative BH3 domain, required for antiviral activity. ApoL9a and b isoforms interact with cellular prohibitin 1 (Phb1) and prohibitin 2 (Phb2) and this interaction might contribute to ApoL9 antiviral activity. Knocking down Phb2 slightly increased TMEV replication, irrespective of ApoL9 overexpression. The antiviral activity of prohibitins against TMEV contrasts with the pro-viral activity of prohibitins observed for VSV and reported previously for Dengue 2 (DENV-2), Chikungunya (CHIKV) and influenza H5N1 viruses. ApoL9 is thus an example of ISG displaying a narrow antiviral range, which likely acts in complex with prohibitins to restrict TMEV replication. [less ▲]

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See detailHost entry by gamma-herpesviruses-lessons from animal viruses?
Gillet, Laurent ULg; Frederico, Bruno; Stevenson, Philip G.

in Current Opinion in Virology (2015), 15

The oncogenicity of gamma-herpesviruses (gammaHVs) motivates efforts to control them and their persistence makes early events key targets for intervention. Human gammaHVs are often assumed to enter naive ... [more ▼]

The oncogenicity of gamma-herpesviruses (gammaHVs) motivates efforts to control them and their persistence makes early events key targets for intervention. Human gammaHVs are often assumed to enter naive hosts orally and infect B cells directly. However, neither assumption is supported by direct evidence, and vaccination with the Epstein-Barr virus (EBV) gp350, to block virion binding to B cells, failed to reduce infection rates. Thus, there is a need to re-evaluate assumptions about gammaHV host entry. Given the difficulty of analysing early human infections, potentially much can be learned from animal models. Genomic comparisons argue that gammaHVs colonized mammals long before humans speciation, and so that human gammaHVs are unlikely to differ dramatically in behaviour from those of other mammals. Murid Herpesvirus-4 (MuHV-4), which like EBV and the Kaposi's Sarcoma-associated Herpesvirus (KSHV) persists in memory B cells, enters new hosts via olfactory neurons and exploits myeloid cells to spread. Integrating these data with existing knowledge of human and veterinary gammaHVs suggests a new model of host entry, with potentially important implications for infection control. [less ▲]

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See detailCanine idiopathic pulmonary fibrosis is not associated with herpes virus infection
Roels, Elodie ULg; Dourcy, Mickael ULg; Holopainen, S. et al

Poster (2015)

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See detailThe alpha2,3-Sialyltransferase Encoded by Myxoma Virus Is a Virulence Factor that Contributes to Immunosuppression.
Boutard, Berengere; Vankerckhove, Sophie; Markine-Goriaynoff, Nicolas et al

in PloS one (2015), 10(2), 0118806

Myxoma virus (MYXV) induces a lethal disease called Myxomatosis in European rabbits. MYXV is one of the rare viruses that encodes an alpha2,3-sialyltransferase through its M138L gene. In this study, we ... [more ▼]

Myxoma virus (MYXV) induces a lethal disease called Myxomatosis in European rabbits. MYXV is one of the rare viruses that encodes an alpha2,3-sialyltransferase through its M138L gene. In this study, we showed that although the absence of the enzyme was not associated with any in vitro deficit, the M138L deficient strains are highly attenuated in vivo. Indeed, while all rabbits infected with the parental and the revertant strains died within 9 days post-infection from severe myxomatosis, all but one rabbit inoculated with the M138L deficient strains survived the infection. In primary lesions, this resistance to the infection was associated with an increased ability of innate immune cells, mostly neutrophils, to migrate to the site of virus replication at 4 days post-infection. This was followed by the development of a better specific immune response against MYXV. Indeed, at day 9 post-infection, we observed an important proliferation of lymphocytes and an intense congestion of blood vessels in lymph nodes after M138L knockouts infection. Accordingly, in these rabbits, we observed an intense mononuclear cell infiltration throughout the dermis in primary lesions and higher titers of neutralizing antibodies. Finally, this adaptive immune response provided protection to these surviving rabbits against a challenge with the MYXV WT strain. Altogether, these results show that expression of the M138L gene contributes directly or indirectly to immune evasion by MYXV. In the future, these results could help us to better understand the pathogenesis of myxomatosis but also the importance of glycans in regulation of immune responses. [less ▲]

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See detailA gammaherpesvirus infection protects against allergic asthma.
Machiels, Bénédicte ULg; Dourcy, Mickael ULg; Sabatel, Catherine ULg et al

Poster (2014, December 12)

The “hygiene hypothesis” proposes that the augmentation of allergic diseases in developed countries could be linked to a reduced exposure to infections during childhood. Surprisingly, the potential ... [more ▼]

The “hygiene hypothesis” proposes that the augmentation of allergic diseases in developed countries could be linked to a reduced exposure to infections during childhood. Surprisingly, the potential protective role of herpesvirus infections against allergy development has never been addressed directly. In this study, we used the Murid herpesvirus 4 (MuHV-4) to study the impact of a persistent gammaherpesvirus infection on the development of House Dust Mites (HDM)-induced allergic asthma. Our results revealed that MuHV-4 infection affects both the sensitization and the challenging phases of HDM-induced airway allergy. In particular, we highlighted that MuHV-4 infection strongly impacts the lung innate immune response. Indeed, while the dendritic cells remained competent to uptake antigens and to migrate to the draining lymph nodes, MuHV-4 infection impaired their ability to trigger HDM sensitization. In the future, these results could allow us to develop strategies to prevent the development of TH2-skewed responses against respiratory allergens. [less ▲]

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See detailLa virothérapie oncolytique médiée par le virus de la myxomatose
Krygier, David; Gillet, Laurent ULg; Marlier, Didier ULg

in Annales de Médecine Vétérinaire (2013), 157(1), 5-14

Le virus de la myxomatose est un poxvirus du genre Leporipoxvirus qui induit une pathologie spécifique, la myxomatose, chez le lapin européen (Oryctolagus cuniculus). Ce virus a la particularité d’être ... [more ▼]

Le virus de la myxomatose est un poxvirus du genre Leporipoxvirus qui induit une pathologie spécifique, la myxomatose, chez le lapin européen (Oryctolagus cuniculus). Ce virus a la particularité d’être non pathogène pour les autres espèces de vertébrés y compris l’homme. Le virus de la myxomatose (MYXV) présente aussi, de manière inattendue, un tropisme pour les cellules cancéreuses humaines in vitro ainsi qu’un potentiel oncolytique in vivo. La tolérance de ces cellules au MYXV est intimement liée au niveau intracellulaire d’Akt phosphorylée. Cette enzyme, est une serine/thréonine protéine kinase qui joue un rôle essentiel dans de nombreux processus cellulaires et fait partie de la voie de signalisation PI3k/Akt/mTOR (mammalian target of rapamycin), fréquemment amplifiée par l’oncogénèse. La protéine virale à répétitions ankyrines, M-T5, interagit avec Akt ce qui module le tropisme du MYXV pour les cellules tumorales humaines. Un régulateur de la croissance cellulaire et du métabolisme situé en aval d’Akt, mTOR, est spécifiquement inhibé par la rapamycine. Ainsi, l’utilisation de la rapamycine en combinaison avec le MYXV permet d’augmenter la concentration d’Akt phosphorylée, et par conséquent, d’amplifier l’oncolyse. Un meilleur contrôle chimique de la voie de signalisation d’Akt ou de la modification génétique de son génome constituera une étape décisive pour que le MYXV devienne l’un des nouveaux traitements des cancers chez l’homme [less ▲]

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See detailProteomic characterization of murid herpesvirus 4 extracellular virions.
Vidick, Sarah ULg; Leroy, Baptiste; Gonon Rodrigues Palmeira, Leonor ULg et al

in PloS one (2013), 8(12), 83842

Gammaherpesvirinae, such as the human Epstein-Barr virus (EBV) and the Kaposi's sarcoma associated herpesvirus (KSHV) are highly prevalent pathogens that have been associated with several neoplastic ... [more ▼]

Gammaherpesvirinae, such as the human Epstein-Barr virus (EBV) and the Kaposi's sarcoma associated herpesvirus (KSHV) are highly prevalent pathogens that have been associated with several neoplastic diseases. As EBV and KSHV are host-range specific and replicate poorly in vitro, animal counterparts such as Murid herpesvirus-4 (MuHV-4) have been widely used as models. In this study, we used MuHV-4 in order to improve the knowledge about proteins that compose gammaherpesviruses virions. To this end, MuHV-4 extracellular virions were isolated and structural proteins were identified using liquid chromatography tandem mass spectrometry-based proteomic approaches. These analyses allowed the identification of 31 structural proteins encoded by the MuHV-4 genome which were classified as capsid (8), envelope (9), tegument (13) and unclassified (1) structural proteins. In addition, we estimated the relative abundance of the identified proteins in MuHV-4 virions by using exponentially modified protein abundance index analyses. In parallel, several host proteins were found in purified MuHV-4 virions including Annexin A2. Although Annexin A2 has previously been detected in different virions from various families, its role in the virion remains controversial. Interestingly, despite its relatively high abundance in virions, Annexin A2 was not essential for the growth of MuHV-4 in vitro. Altogether, these results extend previous work aimed at determining the composition of gammaherpesvirus virions and provide novel insights for understanding MuHV-4 biology. [less ▲]

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