Larvicidal activity of Bacillus thuringiensis var. israelensis Cry11Aa toxin against Haemonchus contortus

• Published in: Parasitology Vol. 143; no. 12; pp. 1665 - 1671
• Main Authors: DE LARA, ANA PAULA DE SOUZA STORI, LORENZON, LUCAS BIGOLIN, VIANNA, ANA MUÑOZ, SANTOS, FRANCISCO DENIS SOUZA, PINTO, LUCIANO SILVA, AIRES BERNE, MARIA ELISABETH, LEITE, FÁBIO PEREIRA LEIVAS
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.10.2016
• Subjects: Animals; Bacillus thuringiensis; Bacterial Proteins - genetics; Bacterial Proteins - toxicity; Biological Assay; Biological Therapy - methods; Disease Models, Animal; Endotoxins - genetics; Endotoxins - toxicity; Escherichia coli; Escherichia coli - genetics; Escherichia coli - metabolism; Haemonchiasis - parasitology; Haemonchiasis - therapy; Haemonchus - drug effects; Haemonchus - physiology; Haemonchus contortus; Hemolysin Proteins - genetics; Hemolysin Proteins - toxicity; Insecticides - toxicity; Larva - drug effects; Larva - physiology; Recombinant Proteins - genetics; Recombinant Proteins - toxicity; Sheep; Survival Analysis; Time Factors; Treatment Outcome; Cry11Aa; Bacillus thuringiensis var. israelensis; Haemonchus contortus; biological control
• ISSN: 0031-1820; 1469-8161
• DOI: 10.1017/S0031182016001451

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.