Tuyển tập các báo cáo nghiên cứu khoa học quốc tế về bệnh thú y đề tài: The expression of plasmid mediated afimbrial adhesin genes in an avian septicemic Escherichia coli strain | J. Vet. Sci. 2008 9 1 75-83 JOURNAL OF Veterinary Science The expression of plasmid mediated afimbrial adhesin genes in an avian septicemic Escherichia coli strain 1. 1 1 12 Eliana Guedes Stehling Tatiana Amabile Campos Marcelo Brocchi Vasco Ariston de Carvalho Azevedo Wanderley Dias da Silveira1 Department of Microbiology and Immunology Institute of Biology CP 6109 Campinas State University Campinas CEP 13081-862 sP Brazil 2Department of Cellular Biology Biosciences Institute Federal University of Minas Gerais Belo Horizonte MG Brazil An Escherichia coli strain SEPT13 isolated from the liver of a hen presenting clinical signs of septicaemia had a LD50 of X 105 CFU ml in one-day-old chickens expressed la Ib E1 E3 K and B colicins and aerobactin. The strain was ampicillin and streptomycin resistant and found to have fim A csgA and tsh DNA related sequences it could adhere to and invade HEp-2 and tracheal epithelial cells expressed fimbriae observed by electron microscopy and had five plasmids of 43 56 and 88 MDa. Transposon mutagenesis of strain SEPT13 with transposon TnphoA resulted in a mutant strain named ST16 that had a LD50 of X 1012 CFU ml. All other biological characteristics of strain ST16 were the same as those detected for strain SEPT13 except for the migration of an 88 MDa plasmid to the 93 MDa position indicating the insertion of the transposon into the 88 MDa plasmid. The 93 MDa plasmid of strain ST16 was transferred by electroporation assay to non-pathogenic receptor strains E. coli strains K12 MS101 and HB101 resulting in transformant strains A and B respectively. These strains exhibited adhesion properties to in vitro cultivated HEp-2 cells but did not have the capacity for invasion. The adherence occurred despite the absence of fimbriae this finding suggests that the 88 MDa plasmid has afimbrial adhesin genes. Keywords adhesion avian Escherichia coli plasmids Introduction Escherichia coli is frequently found as a normal inhabitant of
