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In vitro susceptibility of ten Haemonchus contortus isolates from different geographical origins towards acetone:water extracts of two tannin rich plants

Chan-Pérez, José Israel and Torres-Acosta, Juan Felipe de Jesús and Sandoval-Castro, Carlos Alfredo and Hoste, Hervé and Castañeda-Ramírez, Gloria Sarahí and Vilarem, Gérard and Mathieu, Céline In vitro susceptibility of ten Haemonchus contortus isolates from different geographical origins towards acetone:water extracts of two tannin rich plants. (2016) Veterinary Parasitology, 217. 53-60. ISSN 0304-4017

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Official URL: https://doi.org/10.1016/j.vetpar.2015.11.001

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 8000μg/ml PBS). Additional concentrations were tested for O. viciifolia (75, 100, 200 and 400μg/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, 5000μg/ml, 5000μg/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 14106μg (RR from 2.01 to 6.40). The O. viciifolia extract showed higher variability with EC50 values ranging from 104 to 4783μg (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.

Item Type:Article
HAL Id:hal-02439924
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
French research institutions > Institut National de la Recherche Agronomique - INRA (FRANCE)
Other partners > Universidad Autónoma de Yucatán - UADY (MEXICO)
Laboratory name:
Funders:
CONACYT- Mexico
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Deposited On:14 Jan 2020 17:56

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