RESUMO
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.
Assuntos
Proteínas de Bactérias/toxicidade , Endotoxinas/toxicidade , Haemonchus/efeitos dos fármacos , Proteínas Hemolisinas/toxicidade , Inseticidas/toxicidade , Animais , Toxinas de Bacillus thuringiensis , Proteínas de Bactérias/genética , Bioensaio , Terapia Biológica/métodos , Modelos Animais de Doenças , Endotoxinas/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Hemoncose/parasitologia , Hemoncose/terapia , Haemonchus/fisiologia , Proteínas Hemolisinas/genética , Larva/efeitos dos fármacos , Larva/fisiologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/toxicidade , Ovinos , Análise de Sobrevida , Fatores de Tempo , Resultado do TratamentoRESUMO
In recent years, there been significant progress toward develop more efficient vaccines. Different compounds with adjuvant capacity have been tested; however, no compound has emerged that suitable for universal use. Several efforts have been made to produce effective vaccines against Bovine herpesvirus 5 (BoHV-5), an important cattle pathogen. In this study we examine the use the probiotic Bacillus cereus var. Toyoi as a potential adjuvant to improve BoHV-5 vaccine efficacy. We observed in the supplemented animals a systemic enhanced IgG antibody response toward Th1, and increased IFN-γ, IL-12 and IL-10 cytokines mRNA levels. These results suggest that this probiotic could provide a promising means of improving vaccine efficacy, particularly those vaccines that rely on a cell-mediated immune response.
