title: In vitro susceptibility of ten Haemonchus contortus isolates from different geographical origins towards acetone:water extracts of two tannin rich plants.
abstract: The aim of the study was to examine the variation in the in vitro susceptibility of ten Haemonchus contortus isolates from different geographical origins using respective egg hatch assays (EHA) with acetone:water extracts of two tannin containing plants, chimay (Acacia pennatula) and sainfoin (Onobrychis viciifolia). Fresh eggs were incubated in PBS with different concentrations of each extract (0, 600, 1200, 2400, 3600, 5000 and 8000 μg/ml PBS). Additional concentrations were tested for O. viciifolia (75, 100, 200 and 400 μg/ml PBS). Effective concentrations 50% (EC50), with the corresponding 95% confidence interval (95% CI), were calculated for every isolate with both extracts. Moreover, a resistance ratio (RR) was calculated to compare the isolates, using the most susceptible isolate for each extract as the respective reference. A second set of incubations were made using polyvinylpolypyrrolidone (PVPP) (0, 5000 μg/ml, 5000 μg/ml+PVPP) to determine the influence of polyphenols on the AH effect. The proportion of morulated eggs, eggs with L1 larvae failing eclosion (%LFE), and emerged larvae were estimated at different extract concentrations. Data of each isolate was used to calculate the effective concentration 50% (EC50) for each extract. The EC50 of each isolate was used to determine resistance ratio (RR) for the different isolates. For the 2 extracts, a susceptibility variation in egg hatching was observed for the different H. contortus isolates. The EC50 values for A. pennatula ranged from 2203 to 14106 μg (RR from 2.01 to 6.40). The O. viciifolia extract showed higher variability with EC50 values ranging from 104 to 4783 μg (RR from 3.66 to 45.74). The main AH effects of the two extracts tested on the ten isolates consisted in blocking the emergence of L1 larvae (higher% LFE). Additional observations on emerged larvae showed that extract exposure caused alterations in the internal structure, separating the cuticle from the pharynx, bulb and intestinal cells. The use of PVPP revealed that (a) condensed tannins were not the sole plant secondary metabolites responsible for the AH effects, and (b) different H. contortus isolates showed variability in the role of tannins either on the ovicidal effect or the %LFE.
authors.affiliation: FMVZ, Universidad Autónoma de Yucatán, Km 15.5 Carretera Mérida-Xmatkuil, Mérida, Yucatán, Mexico.
authors.forename: J I
authors.initials: JI
authors.lastname: Chan-Pérez
authors.affiliation: FMVZ, Universidad Autónoma de Yucatán, Km 15.5 Carretera Mérida-Xmatkuil, Mérida, Yucatán, Mexico. Electronic address: tacosta@uady.mx.
authors.forename: J F J
authors.initials: JF
authors.lastname: Torres-Acosta
authors.affiliation: FMVZ, Universidad Autónoma de Yucatán, Km 15.5 Carretera Mérida-Xmatkuil, Mérida, Yucatán, Mexico.
authors.forename: C A
authors.initials: CA
authors.lastname: Sandoval-Castro
authors.affiliation: INRA UMR 1225 Interactions Hôte Agents Pathogènes, 23 Chemin des Capelles, F31076 Toulouse, France.
authors.forename: H
authors.initials: H
authors.lastname: Hoste
authors.affiliation: FMVZ, Universidad Autónoma de Yucatán, Km 15.5 Carretera Mérida-Xmatkuil, Mérida, Yucatán, Mexico.
authors.forename: G S
authors.initials: GS
authors.lastname: Castañeda-Ramírez
authors.affiliation: Université de Toulouse, INP-ENSIACET, LCA (Laboratoire de Chimie Agro industrielle), F31030 Toulouse, France.
authors.forename: G
authors.initials: G
authors.lastname: Vilarem
authors.affiliation: Université de Toulouse, INP-ENSIACET, LCA (Laboratoire de Chimie Agro industrielle), F31030 Toulouse, France.
authors.forename: C
authors.initials: C
authors.lastname: Mathieu
mesh_terms: D000045:Acacia / Q000737:chemistry*; D000096:Acetone / Q000737:chemistry; D000818:Animals; D000969:Antinematodal Agents / Q000494:pharmacology; D007887:Fabaceae / Q000737:chemistry*; D006189:Haemonchus / Q000187:drug effects*; D020128:Inhibitory Concentration 50; D010063:Ovum / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*; D011205:Povidone / Q000031:analogs & derivatives / Q000494:pharmacology; D013045:Species Specificity; D013634:Tannins / Q000494:pharmacology; D014867:Water / Q000737:chemistry
chemical_list: D000969:Antinematodal Agents; D010936:Plant Extracts; D013634:Tannins; D014867:Water; D000096:Acetone; C077842:polyvinylpolypyrrolidone; D011205:Povidone
keywords: Acacia pennatula; Egg hatch assay; Haemonchus contortus; Onobrychis viciifolia; Plant secondary metabolites