Differences in virulence attributes between cytolethal distending toxin positive and negative Campylobacter jejuni strains.
Campylobacter jejuni is a common gastrointestinal bacterial pathogen. Although cytolethal distending toxin (CDT) is proposed to be an important virulence determinant of this pathogen, how CDT(+) and CDT(-) strains differ in their biological properties remains largely unknown. The virulence properties of CDT(+) and CDT(-) strains were studied on HeLa cells and in the suckling mouse model. Presence of the cdtB gene in Campylobacter species was determined by PCR. Five each of CDT(+) and CDT(-) C. jejuni strains were subjected to adherence, invasion and cytotoxicity assay on the HeLa cell line. Bacterial culture supernatants with and without CDT activity were inoculated intragastrically into 2-day-old suckling mice. The mice were sacrificed within 48 h. Histopathological examination of stomach, jejunum, ileum and colon was performed by haematoxylin/eosin staining. cdtB was detected in 88 % and 14 % of C. jejuni and Campylobacter coli strains, respectively. CDT(+) C. jejuni strains adhered to and invaded HeLa cells in significantly higher numbers than CDT(-) strains [CDT(+) vs CDT(-), adherence 2.7 x 10(4)+/-3.5 x 10(4) vs 2.7 x 10(2)+/-1.9 x 10(2); invasion 1.0 x 10(3)+/-1.3 x 10(3) vs 1.4 x 10(1)+/-3.1 x 10(1); P<0.01]. Culture supernatants of all CDT(+) strains demonstrated CDT activity on HeLa cells. Mice inoculated with supernatant containing CDT activity had moderate to severe pathology in different parts of their gastrointestinal tract, with the colon being the major target. Mice inoculated with supernatant lacking CDT activity showed no significant pathology in the gastrointestinal tract. The results demonstrate that CDT(+) C. jejuni strains adhere to and invade epithelial cells more efficiently than CDT(-) strains. CDT is responsible for intestinal pathology and the colon is the major target.
Jain
Deepika
D
Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, India.
Prasad
Kashi Nath
KN
Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, India.
Sinha
Sushmita
S
Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, India.
Husain
Nuzhat
N
Department of Pathology, King George's Medical University, Lucknow 226001, India.
D000818:Animals; D000833:Animals, Suckling; D001422:Bacterial Adhesion; D001427:Bacterial Toxins / Q000378:metabolism* / Q000633:toxicity*; D002169:Campylobacter Infections / Q000382:microbiology / Q000473:pathology*; D016123:Campylobacter jejuni / Q000378:metabolism / Q000472:pathogenicity*; D017931:DNA Primers; D004195:Disease Models, Animal; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014774:Virulence
D001427:Bacterial Toxins; D017931:DNA Primers; C067044:cytolethal distending toxin