Characterization of genetically matched isolates of Campylobacter jejuni reveals that mutations in genes involved in flagellar biosynthesis alter the organism's virulence potential.
Phenotypic and genotypic evidence suggests that not all Campylobacter jejuni isolates are pathogenic for humans. We hypothesized that differences in gene content or gene expression alter the degree of pathogenicity of C. jejuni isolates. A C. jejuni isolate (Turkey) recovered from a turkey and a second C. jejuni isolate (CS) recovered from a chicken differed in their degrees of in vitro and in vivo virulence. The C. jejuni Turkey isolate invaded INT 407 human epithelial cells and secreted the Cia (Campylobacter invasion antigen) proteins, while the C. jejuni CS isolate was noninvasive for human epithelial cells and did not secrete the Cia proteins. Newborn piglets inoculated with the C. jejuni Turkey isolate developed more severe clinical signs of campylobacteriosis than piglets inoculated with the C. jejuni CS isolate. Additional work revealed that flagellin was not expressed in the C. jejuni CS isolate. Microarray and real-time reverse transcription-PCR analyses revealed that all flagellar class II genes were significantly downregulated in the C. jejuni CS isolate compared to the C. jejuni Turkey isolate. Finally, nucleotide sequencing of the flgR gene revealed the presence of a single residue that was different in the FlgR proteins of the C. jejuni Turkey and CS isolates. Complementation of the C. jejuni CS isolate with a wild-type copy of the flgR gene restored the isolate's motility. Collectively, these findings support the hypothesis that critical differences in gene content or gene expression can alter the pathogenic potential of C. jejuni isolates.
Malik-Kale
Preeti
P
School of Molecular Biosciences, Washington State University, Pullman, WA 99164-4233, USA.
Raphael
Brian H
BH
Parker
Craig T
CT
Joens
Lynn A
LA
Klena
John D
JD
Quiñones
Beatriz
B
Keech
Amy M
AM
Konkel
Michael E
ME
D000818:Animals; D000942:Antigens, Bacterial / Q000096:biosynthesis; D002169:Campylobacter Infections / Q000382:microbiology / Q000662:veterinary; D016123:Campylobacter jejuni / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D002645:Chickens; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000382:microbiology; D005407:Flagella / Q000235:genetics*; D005408:Flagellin / Q000096:biosynthesis; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D006801:Humans; D009068:Movement; D020411:Oligonucleotide Array Sequence Analysis; D017354:Point Mutation; D012329:RNA, Bacterial / Q000032:analysis / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D013552:Swine; D014422:Turkeys; D014774:Virulence / Q000235:genetics
D000942:Antigens, Bacterial; D012329:RNA, Bacterial; D012333:RNA, Messenger; D005408:Flagellin