RESUMO
AIMS: To identify a fast, economic and reliable method for preselecting lactic acid-producing bacterial (LAB) isolates to control enterotoxigenic Escherichia coli (ETEC). METHODS AND RESULTS: Two assays with porcine intestinal epithelial IPEC-J2 cells or Caenorhabditis elegans for selecting effective probiotic candidates were compared. Both assays were based on measuring death of cells or worms caused by ETEC strain JG280. Six of 13 LAB isolates showed ≥50% protection in each assay, among which only four isolates (≥50% protection) were consistently selected by both assays. Isolate CL9 (Lactobacillus reuteri) was further studied. It reduced gene expression of estA, estB and elt in JG280 in both assays. Furthermore, the isolate protected IPEC-J2 and C. elegans from cell and worm death caused by STa, STb or LT enterotoxin expressed in E. coli DH5α. CL9 also promoted host defensive responses by decreasing IL-8 and increasing IL-10 production in IPEC-J2 cells and expression of antimicrobial peptide genes clec-60, clec-85 in C. elegans. CONCLUSIONS: Caenorhabditis elegans is useful for preselecting probiotic candidates to control ETEC after initial screening with IPEC-J2 cells. SIGNIFICANCE AND IMPACT OF THE STUDY: A combination of IPEC-J2 cell and C. elegans assays can improve the effectiveness in preselecting probiotic candidates.
Assuntos
Caenorhabditis elegans/efeitos dos fármacos , Escherichia coli Enterotoxigênica/efeitos dos fármacos , Células Epiteliais/efeitos dos fármacos , Limosilactobacillus reuteri/fisiologia , Probióticos/farmacologia , Animais , Antibiose , Peptídeos Catiônicos Antimicrobianos/agonistas , Peptídeos Catiônicos Antimicrobianos/biossíntese , Caenorhabditis elegans/microbiologia , Linhagem Celular , Escherichia coli Enterotoxigênica/crescimento & desenvolvimento , Enterotoxinas/antagonistas & inibidores , Enterotoxinas/biossíntese , Células Epiteliais/microbiologia , Infecções por Escherichia coli/dietoterapia , Infecções por Escherichia coli/microbiologia , Infecções por Escherichia coli/veterinária , Interleucina-10/agonistas , Interleucina-10/metabolismo , Interleucina-8/antagonistas & inibidores , Interleucina-8/metabolismo , Intestinos/efeitos dos fármacos , Intestinos/microbiologia , Modelos Biológicos , Suínos , Doenças dos Suínos/dietoterapia , Doenças dos Suínos/microbiologiaRESUMO
Genomic DNA from four strains of geese was analyzed for the presence of endogenous viral elements using a probe that can detect over 20 Rous-associated endogenous viral genes (ev genes) in chickens, as well as a probe and protocol that detects endogenous avian viruses (EAV). Southern blot analysis of genomic DNA did not reveal any ev genes in DNA of 15 geese from Chinese, Synthetic, or two Embden goose strains. Even under low stringency conditions, using a probe that covered most of the polymerase (pol) gene of the Rous-associated virus (RAV) and that revealed EAV elements in a chicken without ev genes, no viral loci were evident in goose DNA.