Virulence Factors of Avian Escherichia coli

Abstract

A total of 45 strains of Escherichia coli isolates from chickens with colisepticemia were examined for virulence factors commonly found in pathogenic groups of E. coli. These strains were studied for the following: pathogenicity in 1-day-old chicks; toxin, hemolysin, and colicin production; cell invasiveness and adherence; hemagglutination for fimbriae detection; serum resistance; aerobactin production in iron-limited conditions; and plasmid content. The characteristics exhibited by virulent strains were invasion for HeLa and chicken fibroblast cells, serum resistance, colicin V, and aerobactin production. None of the isolates were toxigenic or positive in hemagglutination tests. The molecular genetic studies of the virulence factors by agarose electrophoresis showed that the plasmids of these strains are of high molecular weight.

Colibacillosis in poultry: unravelling the molecular basis of virulence of avian pathogenicEscherichia coliin their natural hosts

“…Resistance to complement-mediated lysis and opsonophagocytosis is believed to play an important role in APEC virulence (Vidotto et al, 1990;Nolan et al, 1992aNolan et al, , 2003. A region on ColV plasmids harbouring traT and iss was first linked to serum resistance and virulence (Binns et al, 1979).…”

Avian pathogenicEscherichia colitransmission from broiler breeders to their progeny in an integrated poultry production chain

“…Escherichia coli is present in the normal intestinal flora of birds. Only some strains with specific virulence attributes, designated as avian pathogenic E. coli (APEC), are able to cause disease such as acute colisepticaemia, fibrinopurulent polyserositis, aerosacculitis, pericarditis, salpingitis, synovitis, omphalitis, yolk sac infection, swollen head syndrome, coligranuloma, and cellulitis (Vidotto et al ., 1990;Dozois et al ., 1994;Gomis et al ., 1997;Pourbakhsh et al ., 1997;Dho-Moulin & Fairbrother, 1999). Among the virulence factors involved in the pathogenesis of colibacillosis, F1 (type 1) fimbriae have been shown to adhere to chicken respiratory epithelial cells of the pharynx and trachea (Dozois et al ., 1994;Dho-Moulin & Fairbrother, 1999), Temperature-sensitive haemagglutinin (Tsh) plays a role in the colonization of air sacs (Dozois et al ., 2000), the aerobactin ironsequestering system allows E. coli growth in a low concentration of free iron in physiological liquids such as blood (Dho-Moulin & Fairbrother, 1999) and P fimbriae are important in the later stages of infection for the adhesion to internal organs (Dho-Moulin & Fairbrother, 1999), giving resistance to phagocytosis (Pourbakhsh et al ., 1997).…”

Cloning, expression and sequence diversity of iss gene from avian pathogenic Escherichia coli (APEC) isolated in Brazil

“…The avian pathogenic Escherichia coli strain APEC9 used in this study was recovered from the trachea of a colisepticemic chicken in the Parana State-Brazil (VIDOTTO et al, 1990). This strain shows resistance to tetracycline, ampicillin and serum complement.…”

“…This strain shows resistance to tetracycline, ampicillin and serum complement. It is produces colicin V, and has an iron uptake system mediated by aerobactin and carries one large plasmid of approximately 120 kilobases (Kb) (VIDOTTO et al, 1990). The APEC9 strain presented serotype O2:H9:K1 (MOURA; IRINO; VIDOTTO, 2001) and was pathogenic to 1-day-old chickens by means of pathogenicity test, presenting LD 50 of 1 x 10 5 cells/ ml.…”

“…Escherichia coli strains designated as avian pathogenic E. coli (APEC) possess specific virulence factors and are able to cause avian colibacillosis (VIDOTTO et al, 1990;DHO-MOULIN;FAIRBROTHER, 1999). This disease is a serious problem for the poultry industry, since it causes high economic losses.…”