Salmonella enterica serovar Dublin strains which are Vi antigen-positive use type IVB pili for bacterial self-association and human intestinal cell entry.
Some strains of Salmonella enterica serovar Dublin are Vi antigen-positive. S. enterica serovar Typhi uses Type IVB pili, encoded adjacent to the viaB locus required for Vi antigen synthesis, to facilitate both eukaryotic cell attachment and bacterial self-association under conditions that favour DNA supercoiling. These pilus-mediated events may be important in typhoid fever pathogenesis. A survey of 17 isolates of S. enterica serovar Dublin showed that all strains which carried the viaB region also carried a serovar Typhi-like Type IVB pil operon, and all serovar Dublin Vi antigen-negative isolates lacked the pil operon. The pil operon was completely sequenced from one of the Vi(+) serovar Dublin strains, and was almost identical (4 nt changes; 3 aa changes, in over 10 kb) to that of serovar Typhi. A pilS mutant of one serovar Dublin strain was constructed, and shown to invade cultured human intestinal INT407 cells to an extent only 20% that of the wild-type parent. Purified prePilS protein inhibited INT407 cell entry by serovar Dublin. The wild-type serovar Dublin strain, but not the pilS mutant, self-associated. The data suggest that the serovar Dublin Type IVB pil operon may increase the human-invasiveness of serovar Dublin, compared to pil-free strains.
Morris
Christina
C
Department of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China. bctina@ust.hk
Tam
Connie K P
CK
Wallis
Timothy S
TS
Jones
Philip W
PW
Hackett
Jim
J
D000942:Antigens, Bacterial / Q000235:genetics*; D001422:Bacterial Adhesion / Q000235:genetics*; D002460:Cell Line; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000502:physiology*; D023061:Gene Order; D005798:Genes, Bacterial; D006801:Humans; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009876:Operon; D016133:Polymerase Chain Reaction / Q000379:methods; D011135:Polysaccharides, Bacterial / Q000235:genetics*; D019779:Salmonella enterica / Q000235:genetics / Q000472:pathogenicity*; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
D000942:Antigens, Bacterial; D004269:DNA, Bacterial; D011135:Polysaccharides, Bacterial