title: PorA protein of Campylobacter jejuni is not a cytotoxin mediating inflammatory diarrhoea.
abstract: Campylobacter jejuni is a major food-borne pathogen and a leading cause of diarrhoea. A cytotoxin is most likely involved in the pathogenesis of inflammatory diarrhoea due to C. jejuni. A 45-kDa outer membrane protein encoded by the porA gene was reported to exhibit cytotoxic activity for cultured mammalian cells in vitro. We cloned and expressed the porA gene in Escherichia coli BL21 codon plus RIL strain using the fusion vector pGEX-4T-1. The fusion protein solubilised in urea in denatured form or solubilised in Empigen BB in native form or their thrombin-cleaved products did not exhibit cytotoxic activity for Chinese hamster ovary (CHO) cells. The urea-solubilised fusion protein did not induce fluid accumulation in the rabbit ileal loop assay. All 76 clinical isolates of Campylobacter spp. tested were positive for porA by PCR, but only 13 isolates were positive for cytotoxin on CHO cells. Both cytotoxin-positive as well as cytotoxin-negative strains expressed PorA as determined by immunoblot analysis. These findings show that the porA gene product of C. jejuni is not a cytotoxin mediating inflammatory diarrhoea.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Kuwait University, PO Box 24923, Safat 13110, Kuwait.
authors.forename: Islam
authors.initials: I
authors.lastname: Khan
authors.forename: Ben
authors.initials: B
authors.lastname: Adler
authors.forename: Shilpa
authors.initials: S
authors.lastname: Haridas
authors.forename: M John
authors.initials: MJ
authors.lastname: Albert
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism / Q000633:toxicity*; D001427:Bacterial Toxins / Q000633:toxicity; D016466:CHO Cells; D016123:Campylobacter jejuni / Q000472:pathogenicity*; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D003603:Cytotoxins / Q000633:toxicity; D003967:Diarrhea / Q000382:microbiology* / Q000503:physiopathology; D015870:Gene Expression; D007082:Ileum / Q000503:physiopathology; D018272:Porins / Q000378:metabolism / Q000633:toxicity*; D011817:Rabbits; D011994:Recombinant Proteins / Q000633:toxicity; D014709:Vero Cells
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003603:Cytotoxins; D018272:Porins; D011994:Recombinant Proteins; C095080:major outer membrane protein, Campylobacter jejuni