Antiviral Activity of Some Plants Used in Nepalese Traditional Medicine

Methanolic extracts of 41 plant species belonging to 27 families used in the traditional medicine in Nepal have been investigated for in vitro antiviral activity against Herpes simplex virus type 1 (HSV-1) and influenza virus A by dye uptake assay in the systems HSV-1/Vero cells and influenza virus A/MDCK cells. The extracts of Astilbe rivularis, Bergenia ciliata, Cassiope fastigiata and Thymus linearis showed potent anti-herpes viral activity. The extracts of Allium oreoprasum, Androsace strigilosa, Asparagus filicinus, Astilbe rivularis, Bergenia ciliata and Verbascum thapsus exhibited strong anti-influenza viral activity. Only the extracts of A. rivularis and B. ciliata demonstrated remarkable activity against both viruses

Hexanoic Acid Treatment Prevents Systemic MNSV Movement in Cucumis melo Plants by Priming Callose Deposition Correlating SA and OPDA Accumulation

[EN] Unlike fungal and bacterial diseases, no direct method is available to control viral diseases. The use of resistance-inducing compounds can be an alternative strategy for plant viruses. Here we studied the basal response of melon to Melon necrotic spot virus (MNSV) and demonstrated the efficacy of hexanoic acid (Hx) priming, which prevents the virus from systemically spreading. We analysed callose deposition and the hormonal profile and gene expression at the whole plant level. This allowed us to determine hormonal homeostasis in the melon roots, cotyledons, hypocotyls, stems and leaves involved in basal and hexanoic acid-induced resistance (Hx-IR) to MNSV. Our data indicate important roles of salicylic acid (SA), 12-oxo-phytodienoic acid (OPDA), jasmonic-isoleucine, and ferulic acid in both responses to MNSV. The hormonal and metabolites balance, depending on the time and location associated with basal and Hx-IR, demonstrated the reprogramming of plant metabolism in MNSV-inoculated plants. The treatment with both SA and OPDA prior to virus infection significantly reduced MNSV systemic movement by inducing callose deposition. This demonstrates their relevance in Hx-IR against MNSV and a high correlation with callose deposition. Our data also provide valuable evidence to unravel priming mechanisms by natural compounds.This work has been supported by grants from the Spanish Ministry of Science and Innovation (AGL2010-22300-C03-01-02, AGL2013-49023-C03-01-02-R and BIO2014-54862-R), co-funded by the European Regional Development Fund.Fernandez-Crespo, E.; Navarro Bohigues, JA.; Serra Soriano, M.; Finiti, I.; García Agustín, P.; Pallás Benet, V.; Gonzalez-Bosch, C. (2017). Hexanoic Acid Treatment Prevents Systemic MNSV Movement in Cucumis melo Plants by Priming Callose Deposition Correlating SA and OPDA Accumulation. Frontiers in Plant Science. 8:1-15. https://doi.org/10.3389/fpls.2017.01793S1158Alazem, M., & Lin, N. (2014). Roles of plant hormones in the regulation of host–virus interactions. Molecular Plant Pathology, 16(5), 529-540. doi:10.1111/mpp.12204Ando, S., Obinata, A., & Takahashi, H. (2014). WRKY70 interacting with RCY1 disease resistance protein is required for resistance to Cucumber mosaic virus in Arabidopsis thaliana. Physiological and Molecular Plant Pathology, 85, 8-14. doi:10.1016/j.pmpp.2013.11.001Anfoka, G. H. (2000). Benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester induces systemic resistance in tomato (Lycopersicon esculentum. Mill cv. Vollendung) to Cucumber mosaic virus. 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Nature du complexe viral impliqué dans le mouvement à longue distance du virus de la jaunisse du navet

Turnip yellows virus (TuYV) is a polerovirus restricted to phloem cells. The genomic RNA is protected in icosahedral particles composed of two proteins among which the major coat protein (CP). In this project, TuYV transport in the phloem was analysed. The first objective was to identify the nature of the viral complex involved in vascular movement: virions and/or ribonucleoprotein complexes formed of viral RNA associated with proteins. Mutant viruses were modified in the CP gene to inhibit formation of virions. By analyzing their movement in different host plants, in the absence or in the presence of the wild-type CP brought in trans, we demonstrated a strong relation between virion formation and virus long-distance movement. The second objective was to identify cellular partners of the TuYV-P4 protein, a putative movement protein which is host-specific. Two proteins were identified by screening a cDNA library of A. thaliana using the yeast two hybrid technique, and their function in the virus cycle was assessed by performing sub-cellular localizations and infection of A. thaliana KO mutants.Le virus de la jaunisse du navet (TuYV) est un polérovirus restreint aux cellules du phloème. Son ARN génomique est protégé par des particules icosaédriques formées de deux protéines virales dont la protéine de capside (CP). Le sujet de la thèse consistait à étudier le mouvement du TuYV dans le système vasculaire. Le premier objectif était d’identifier la nature du complexe viral cheminant dans les tubes criblés : virions et/ou complexes ribonucléoprotéiques constitués de l’ARN associé à différentes protéines. Des mutants viraux ont été modifiés dans la CP pour empêcher la formation de virions. L’analyse de leur mouvement dans différentes espèces végétales, en absence ou en présence de CP de type sauvage apportées en trans, a permis de démontrer une étroite relation entre la formation de virions et le transport à longue distance. Le second objectif de cette étude portait sur l’identification de partenaires cellulaires de la protéine P4 du TuYV, une protéine putative de mouvement dont le rôle est peu connu. Deux protéines ont été identifiées par un criblage de banques d’ADNc d’A. thaliana par le système du double hybride dans la levure, et l’analyse de leur implication dans le cycle viral a été amorcée par des expériences de localisation subcellulaire et d’infection de mutants d’A. thaliana

Nature of the viral complex involved in the long distance movement of Turnip yellows virus

Le projet de thèse consistait à étudier le mouvement du Virus de la jaunisse du navet (TuYV) dans le système vasculaire. Le premier objectif était d’identifier la nature du complexe viral cheminant dans les tubes criblés : virions et/ou complexes ribonucléoprotéiques. L’analyse du mouvement de mutants viraux dans différentes espèces végétales, en absence ou en présence de protéines de capside de type sauvage apportées en trans, a permis de démontrer une étroite relation entre la formation de virions et le transport à longue distance. Le second objectif de cette étude portait sur l’identification de partenaires cellulaires de la protéine P4 du TuYV. Deux protéines ont été identifiées par un criblage de banques d’ADNc d’A. thaliana par le système du double hybride dans la levure, et l’analyse de leur implication dans le cycle viral a été amorcée par des expériences de localisation subcellulaire et de validation fonctionnelle in planta.In the project, Turnip yellows virus (TuYV) transport in the phloem was analysed. The first objective was to identify the nature of the viral complex involved in vascular movement: virions and/or ribonucleoprotein complexes. Mutant viruses were modified in the capsid protein gene to inhibit formation of virions. By analyzing their movement in different host plants, in the absence or in the presence of the wild-type capsid proteins brought in trans, we demonstrated a strong relation between virion formation and virus long-distance movement. The second objective was to identify cellular partners of the TuYV-P4 protein, a putative movement protein which is host-specific. Two proteins were identified by screening a cDNA library of A. thaliana using the yeast two hybrid technique, and their function in the virus cycle was assessed by performing sub-cellular localizations and infection of A. thaliana KO mutants