title: Larvicidal activity of Bacillus thuringiensis var. israelensis Cry11Aa toxin against Haemonchus contortus.
abstract: Effective control of gastrointestinal parasites is necessary in sheep production. The development of anthelmintics resistance is causing the available chemically based anthelmintics to become less effective. Biological control strategies present an alternative to this problem. In the current study, we tested the larvicidal effects of Bacillus thuringiensis var. israelensis Cry11Aa toxin against Haemonchus contortus larvae. Bacterial suspensions [2 × 108 colony-forming units (CFU) g-1 of the feces] of B. thuringiensis var. israelensis and recombinant Escherichia coli expressing Cry11Aa toxin were added to naturally H. contortus egg-contaminated feces. The larvae were quantified, and significant reductions of 62 and 81% (P < 0·001) were, respectively observed, compared with the control group. A 30 mL bacterial suspension (1 × 108 CFU mL-1) of B. thuringiensis var. israelensis and recombinant E. coli expressing Cry11Aa toxin were then orally administered to lambs naturally infected with H. contortus. Twelve hours after administration, feces were collected and submitted to coprocultures. Significant larvae reductions (P < 0·001) of 79 and 90% were observed respectively compared with the control group. The results suggest that the Cry11Aa toxin of B. thuringiensis var. israelensis is a promising new class of biological anthelmintics for treating sheep against H. contortus.
authors: Departamento de Microbiologia e Parasitologia,UFPel,Pelotas, RS,Brazil.
authors: Ana Paula DE Souza Stori
authors: AP
authors: DE Lara
authors: Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas (UFPel),Pelotas, RS,Brazil.
authors: Lucas Bigolin
authors: LB
authors: Lorenzon
authors: Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas (UFPel)Pelotas, RS,Brazil.
authors: Ana Muñoz
authors: AM
authors: Vianna
authors: Faculdade de Veterinária,Universidade Federal de Pelotas (UFPel)Pelotas, RS,Brazil.
authors: Francisco Denis Souza
authors: FD
authors: Santos
authors: Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas (UFPel)Pelotas, RS,Brazil.
authors: Luciano Silva
authors: LS
authors: Pinto
authors: Departamento de Microbiologia e Parasitologia,UFPel,Pelotas, RS,Brazil.
authors: Maria Elisabeth
authors: ME
authors: Aires Berne
authors: Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas (UFPel)Pelotas, RS,Brazil.
authors: Fábio Pereira Leivas
authors: FP
authors: Leite
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000633:toxicity*; D001681:Biological Assay; D001691:Biological Therapy / Q000379:methods; D004195:Disease Models, Animal; D004731:Endotoxins / Q000235:genetics / Q000633:toxicity*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006188:Haemonchiasis / Q000469:parasitology / Q000628:therapy; D006189:Haemonchus / Q000187:drug effects* / Q000502:physiology; D006460:Hemolysin Proteins / Q000235:genetics / Q000633:toxicity*; D007306:Insecticides / Q000633:toxicity*; D007814:Larva / Q000187:drug effects / Q000502:physiology; D011994:Recombinant Proteins / Q000235:genetics / Q000633:toxicity; D012756:Sheep; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides; D011994:Recombinant Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Bacillus thuringiensis var. israelensis; Cry11Aa; Haemonchus contortus; biological control