Transfer of plasmid Hly in vivo in pigs intestine

The results of our study suggest the in vivo transfer of Hly plasmid from native pathogenic and enterotoxigenic Escherichia coli strain to autochtonous Escherichia coli, using ileal loop test. To confirm this hypothesis pHly::Tn5 and PHly::Tn3 were obtained using an in vitro recombination method, and introduced to Escherichia coli laboratory strain. For experiments the laboratory strain, carrying pHly::Tn5 and pHly::Tn3 and pHly::Tn5 strain which acquired K88(F4) by means of conjugation, were used. In the study in which the donor Escherichia coli pHly::Tn5 strain, carrying antigen K88(F4), was injected into the ileum, pHly conjugants were isolated from faeces after 48 h in 2 out of 5 pigs, which was a low frequency. After the oral introduction of 10 9 cells of pHly::Tn5 and pHly::Tn3 Escherichia coli strains without the colonizing factor K88(F4), conjugants were not isolated from faeces of experimental animals. However when the pigs received donor CSH55 pHly::Tn5 Escherichia coli strain orally, which were also carrying plasmid K88(F4), transconjugants were obtained in a low frequency of 3 out of 9 pigs. Our experiments confirmed the suggestion of Smith that in vivo transfer of plasmid in the intestine of animals is only possible when the donor transfers the plasmid with high frequency and readily colonizes the intestine. The pHly::Tn5 plasmid acquired by in vitro recombination does not spread with time throughout the autochtonic population of Escherichia coli present in the intestine of swine. The results of our study showed the in vivo transfer in pigs intestine of Hly pathogenicity marker from both native pathogenic strains carrying antigen K88(F4) and constructed donor laboratory strain of Escherichia coli pHly::Tn5 also carrying antigen K88(F4) to autochtonous intestinal strains. Les résultats des expériences suggèrent le transfert in vivo du plasmide Hly de la souche sauvage et entérotoxique de Escherichia coli dans l'anse intestinale du porc. Pour le confirmer on a utilisé des techniques de génie génétique pour l'obtention de pHly::Tn5 et pHly::Tn3. Dans les expériences on a utilisé des souches contenant pHly::Tn5, pHly::Tn3, et pHly::Tn5 dans les quelles pour la méthode de conjugaison on a introduit le plasmide K88(F4). Lorsque la souche de Escherichia coli donatrice Hly::Tn5 contenant l'antigène K88(F4) était injectée dans l'ileon, on a isolé à basse fréquence, des fèces conjugués Hly chez 2 des 5 porcs testés. Après inoculation par voie orale de 1