title: Characterization of a haemolytic phospholipase A(2) activity in clinical isolates of Campylobacter concisus.
abstract: A membrane-bound, haemolytic phospholipase A(2) (PLA(2)) activity was detected in clinical strains of Campylobacter concisus isolated from children with gastroenteritis. The clinical strains were assigned into two molecular groups (genomospecies) based on PCR amplification of their 23S rDNA. This calcium-dependent, heat-stable, haemolytic PLA(2) activity was detected in strains from both genomospecies. A crude haemolysin extract (CHE) was initially prepared from cellular outer-membrane proteins of these isolates and was further fractionated by ultrafiltration. The haemolytic activity of the extracted fraction (R30) was retained by ultrafiltration using a 30 kDa molecular mass cut-off filter, and was designated haemolysin extract (HE). Both CHE and HE had PLA(2) activity and caused stable vacuolating and cytolytic effects on Chinese hamster ovary cells in tissue culture. Primers for the conserved region of pldA gene (phospholipase A gene) from Campylobacter coli amplified a gene region of 460 bp in all tested isolates, confirming the presence of a homologous PLA gene sequence in C. concisus. The detection of haemolytic PLA(2) activity in C. concisus indicates the presence of a potential virulence factor in this species and supports the hypothesis that C. concisus is a possible opportunistic pathogen.
authors.affiliation: Department of Biotechnology and Environmental Biology, RMIT University, PO Box 71, Bundoora, Victoria 3083, Australia 2Microbiology Department, Royal Children's Hospital, Melbourne, Australia 3School of Health Sciences, Deakin University, Melbourne, Australia.
authors.forename: Taghrid S
authors.initials: TS
authors.lastname: Istivan
authors.affiliation: Department of Biotechnology and Environmental Biology, RMIT University, PO Box 71, Bundoora, Victoria 3083, Australia 2Microbiology Department, Royal Children's Hospital, Melbourne, Australia 3School of Health Sciences, Deakin University, Melbourne, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Coloe
authors.affiliation: Department of Biotechnology and Environmental Biology, RMIT University, PO Box 71, Bundoora, Victoria 3083, Australia 2Microbiology Department, Royal Children's Hospital, Melbourne, Australia 3School of Health Sciences, Deakin University, Melbourne, Australia.
authors.forename: Benjamin N
authors.initials: BN
authors.lastname: Fry
authors.affiliation: Department of Biotechnology and Environmental Biology, RMIT University, PO Box 71, Bundoora, Victoria 3083, Australia 2Microbiology Department, Royal Children's Hospital, Melbourne, Australia 3School of Health Sciences, Deakin University, Melbourne, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Ward
authors.affiliation: Department of Biotechnology and Environmental Biology, RMIT University, PO Box 71, Bundoora, Victoria 3083, Australia 2Microbiology Department, Royal Children's Hospital, Melbourne, Australia 3School of Health Sciences, Deakin University, Melbourne, Australia.
authors.forename: Stuart C
authors.initials: SC
authors.lastname: Smith
mesh_terms: D000328:Adult; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000302:isolation & purification; D016466:CHO Cells / Q000187:drug effects / Q000473:pathology; D002167:Campylobacter / Q000201:enzymology* / Q000302:isolation & purification / Q000472:pathogenicity; D002169:Campylobacter Infections / Q000382:microbiology; D002675:Child, Preschool; D006224:Cricetinae; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005759:Gastroenteritis / Q000382:microbiology; D006460:Hemolysin Proteins / Q000032:analysis* / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D015151:Immunoblotting; D007223:Infant; D008055:Lipids / Q000494:pharmacology; D008297:Male; D010741:Phospholipases A / Q000032:analysis* / Q000235:genetics / Q000302:isolation & purification; D013045:Species Specificity; D037521:Virulence Factors / Q000032:analysis
chemical_list: D001425:Bacterial Outer Membrane Proteins; D004791:Enzyme Inhibitors; D006460:Hemolysin Proteins; D008055:Lipids; D037521:Virulence Factors; D010741:Phospholipases A