Phenotypic expression of recombinant plasmids pKT107 and pHK11 in an avirulent avian Escherichia coli.
An avirulent wild-type avian Escherichia coli strain (Av) was electrotransformed with plasmids coding for complement resistance (pKT107) and Colicin V (ColV) production (pHK11) in order to study the effects of complement resistance and ColV production on virulence. Transformants were also compared with the wild type for embryo lethality, uptake by macrophages, motility, growth rate, plasmid content, and hemolysis. Growth rates and complement resistance patterns of strain Av and transformant Av+pHK11 were similar, but Av+pHK11 caused a significantly greater number of deaths in embryos and acquired motility. Transformant Av+pKT107 had a lower rate of phagocytosis, a slower growth rate, and a greater sensitivity to complement, and it changed from being non-hemolytic to expressing alpha-hemolytic action. The 35-kb plasmid present in the wild type was not present in the transformants. Although some of the results demonstrate the difficulties encountered in using wild-type organisms as recipients in virulence studies, the results with Av+pHK11 indicate that ColV production plus the acquisition of motility contributes to the virulence of avian E. coli.
Wooley
R E
RE
Department of Medical Microbiology, College of Veterinary Medicine, University of Georgia, Athens 30602.
Nolan
L K
LK
Brown
J
J
Gibbs
P S
PS
Bounous
D I
DI
D000818:Animals; D000900:Anti-Bacterial Agents / Q000633:toxicity; D015139:Blotting, Southern; D002642:Chick Embryo; D003087:Colicins / Q000096:biosynthesis; D003165:Complement System Proteins / Q000502:physiology; D015342:DNA Probes; D004352:Drug Resistance, Microbial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity*; D005798:Genes, Bacterial; D006168:Guinea Pigs; D008826:Microbial Sensitivity Tests; D010957:Plasmids; D011815:R Factors; D011995:Recombination, Genetic; D014169:Transformation, Bacterial; D014774:Virulence / Q000235:genetics
D000900:Anti-Bacterial Agents; D003087:Colicins; D015342:DNA Probes; D003165:Complement System Proteins