Macroalgae extracts limits Marek’s disease virus load and dissemination in vitro.

Marek’s disease (MD) is a highly contagious lymphoproliferative disease of chickens caused by an alphaherpesvirus, Marek’s disease virus (MDV). MD is presently controlled by systematic vaccination of animals, which protects efficiently against clinical disease. However, MDV vaccines do not prevent the multiplication and spread of MDV field strains generating immunosuppression. They may also favor the emergence of strains with increased virulence. Therefore, MDV persists to be a major problem for the poultry industry generating economic losses estimated at 1-2 billion dollars per year. The development of new sustainable alternative strategies to control MDV is needed. Macroalgae extracts have previously been shown to exert antiviral and immunomodulatory activities that could support the animals to better resist to this challenge.The objective of the study was to explore the effect of sulphated green macroalgae (Ulva sp.) extract (MSP®IMMUNITY) on MDV infection in vitro. To determine the impact on MDV lytic replication, chick embryo fibroblasts (CEFs) were infected and treated with increasing doses of the algae extract. The viral load was quantified at 24, 48, 72 and 96 hours post infection (hpi) by qPCR. The results showed the treatments significantly decreased MDV lytic replication in CEFs in a dose-dependent manner with the strongest effect observed with concentrations of 1ml/l. From 24 hpi, the viral load was reduced by about 80% with the algae extract at a concentration of 2ml/l and this is maintained over time and reached 94% at 96 hpi, A substantial decrease in MDV plaque size (from 2 to 3 fold) was demonstrated suggesting that macroalgae extract impede MDV cell-to-cell spread in vitro. This study provides the first evidence that the use of the macroalgae extracts could be a good alternative to limit MDV infection in poultry

Procédé de sélection d'une lignée cellulaire permissive pour la réplication de virus aviaires

The present invention relates to a method for obtaining an untransformed avian cell line enabling in vitro avian virus replication. Said method includes the following steps: a) culturing avian embryonic stem cells in the presence of a stroma for at least 3 days; b) culturing for at least 2 days in a medium having a low serum concentration; c) culturing for at least 2 days in a medium having a low serum concentration containing 1 to 10 mM of hexamethyleme bisacetamide (HMBA); d) culturing for at least 10 days in a medium having a low serum concentration; and e) culturing or freezing an avian cell line enabling avian virus replication. The invention also relates to the resulting cell line and to the use thereof in vaccine preparationsLa présente invention concerne un procédé d'obtention d'une lignée cellulaire aviaire non transformée permettant la réplication de virus aviaires in vitro, comprenant les étapes suivantes : a) Mise en culture de cellules souches embryonnaires aviaires en présence d'un stroma pendant au moins 3 jours; b) Culture dans un milieu à faible concentration de sérum pendant au moins 2 jours; c) Culture dans un milieu à faible concentration de sérum comprenant entre 1 et 10 mM de hexaméthylène bisacétamide (HMBA), pendant au moins 2 jours; d) Culture dans un milieu à faible concentration de sérum pendant au moins 10 jours; e) Culture ou congélation d'une lignée cellulaire aviaire permettant la réplication de virus aviaires. L'invention est également relative à la lignée cellulaire ainsi obtenue, et à son utilisation dans des préparations vaccinales

Étude des dommages à l'ADN au cours du cyle viral du virus de la maladie de Marek

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MDV infection prolongs survival of B cells in culture

International audienc

Domains of VP22 protein essential for viral dissemination and cell cycle modulation of Marek's disease virus

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Étude des dommages à l’ADN au cours du cycle viral du virus de la Maladie de Marek

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The sulphated polysaccharides extract ulvans from Ulva armoricana limits Marek’s disease virus dissemination in vitro and promotes viral reactivation in lymphoid cells

International audienceBackground: Marek's disease (MD) is a highly contagious lymphoproliferative disease of chickens caused by an alphaherpesvirus, Marek's disease virus (MDV). MD is presently controlled by systematic vaccination of animals, which protects efficiently against the development of clinical disease. However, MDV vaccines do not prevent the multiplication and spread of MDV field strains and may favor the emergence of strains with increased virulence. Therefore, MDV persists to be a major problem for the poultry industry and the development of new alternative strategies to control MDV is needed. Seaweed extracts have previously been shown to exert immunomodulatory and antiviral activities, especially against herpesviruses. The objective of the present study was to explore the effect of Ulva armoricana extracts on MDV infection in vitro. Results: We could demonstrate that the ulvan extract as well as its vitamin-enriched formulation reduce the viral load by about 80% at 24 h post-infection in infected chicken fibroblasts at concentrations that are innocuous for the cells. We also observed a substantial decrease in MDV plaque size suggesting that ulvans impede MDV cell-to-cell spread in vitro. Moreover, we showed that ulvan extract could promote MDV reactivation in lymphoid cells. Conclusions: Our data provide the first evidence that the use of the ulvan extract could be a good alternative to limit MDV infection in poultry

MDV infection prolongs survival of B cells in culture

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Keratinocytes derived from chicken embryonic stem cells support Marek's disease virus infection: a highly differentiated cell model to study viral replication and morphogenesis

Marek's disease is a virus disease with worldwide distribution that causes major losses to poultry production. Vaccines against Marek's disease virus, an oncogenic alphaherpesvirus, reduce tumour formation but have no effect on virus shedding. Successful horizontal virus transmission is linked to the active viral replication in feather follicle epithelial cells of infected chickens, from which infectious viral particles are shed into the environment. The feather follicle epithelium is the sole tissue in which those infectious particles are produced and no in vitro cell-systems can support this highly efficient morphogenesis. We previously characterized embryonic stem-cell-derived keratinocytes, showing they display a marker-gene profile similar to skin keratinocytes, and therefore we tested their susceptibility to Marek's disease virus infection.[br/]We show herein that keratinocytes derived from chicken embryonic stem-cells are fully permissive to the replication of either non-pathogenic or pathogenic Marek's disease viruses. All viruses replicated on all three keratinocyte lines and kinetics of viral production as well as viral loads were similar to those obtained on primary cells. Morphogenesis studies were conducted on infected keratinocytes and on corneocytes, showing that all types of capsids/virions were present inside the cells, but extracellular viruses were absent.[br/]The keratinocyte lines are the first epithelial cell-line showing ectodermal specific markers supporting Marek's disease virus replication. In this in vitro model the replication lead to the production of cell-associated viral progeny. Further work will be devoted to the study of relationship between 3D differentiation of keratinocytes and Marek's disease virus replication

Implication of cellular DNA damage triggered by Marek's disease virus infection in viral replication and pathogenesis

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