title: Invasion of chicken embryo fibroblast cells by avian Pasteurella multocida.
abstract: Invasion of chicken embryo fibroblast (CEF) cells by the virulent encapsulated Pasteurella multocida strains P-1059 (serovar A:3) and X-73 (serovar A:1) and an avirulent noncapsulated derivative P-1059B (serovar -:3) was investigated. The number of intracellular bacteria increased for all the strains after 2, 4 and 6 h post-inoculation to CEF cells. By 6 h post-inoculation, the number of invaded bacteria of encapsulated strains was significantly higher than noncapsulated strain and reached 150- and 112-fold for strains P-1059 and X-73, respectively, while it was 9-fold for strain P-1059B as compared to the number of invaded bacteria recovered after 2 h post-inoculation. Electron microscopy of invasion by encapsulated strains showed that the bacteria were adhering to CEF cells membrane after 1 h of inoculation. By 4-h, one or two bacteria were detected within membrane-bound vacuoles of the intracellular space. The number of intracellular bacteria markedly increased at 14 h post-inoculation. Invasion of all strains was inhibited significantly when the monolayers were treated with periodic acid (P<0.001) or trypsin (P<0.05). The treatment of bacteria with hyaluronidase did not affect invasion. The present results indicate that avian P. multocida capsular type A strains are invasive and that the receptor on CEF cell surface might be glycoprotein.
authors.affiliation: Department of Veterinary Microbiology, Faculty of Veterinary Medicine, Nippon Veterinary and Animal Science University, Musashino, Tokyo 180-8602, Japan.
authors.forename: Hussam
authors.initials: H
authors.lastname: Al-haj Ali
authors.forename: Takuo
authors.initials: T
authors.lastname: Sawada
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Hatakeyama
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Katayama
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Ohtsuki
authors.forename: Osamu
authors.initials: O
authors.lastname: Itoh
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion / Q000276:immunology; D016667:Bacterial Capsules / Q000276:immunology* / Q000648:ultrastructure; D002642:Chick Embryo; D015169:Colony Count, Microbial; D005347:Fibroblasts / Q000382:microbiology* / Q000648:ultrastructure; D006821:Hyaluronoglucosaminidase / Q000494:pharmacology; D008854:Microscopy, Electron / Q000662:veterinary; D010326:Pasteurella Infections / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D016979:Pasteurella multocida / Q000254:growth & development / Q000276:immunology / Q000472:pathogenicity / Q000502:physiology*; D014357:Trypsin / Q000494:pharmacology
chemical_list: D006821:Hyaluronoglucosaminidase; D014357:Trypsin