Characterization of vibrio cholerae O1 antigen as the bacteriophage K139 receptor and identification of IS1004 insertions aborting O1 antigen biosynthesis.
Bacteriophage K139 was recently characterized as a temperate phage of O1 Vibrio cholerae. In this study we have determined the phage adsorption site on the bacterial cell surface. Phage-binding studies with purified lipopolysaccharide (LPS) of different O1 serotypes and biotypes revealed that the O1 antigen serves as the phage receptor. In addition, phage-resistant O1 El Tor strains were screened by using a virulent isolate of phage K139. Analysis of the LPS of such spontaneous phage-resistant mutants revealed that most of them synthesize incomplete LPS molecules, composed of either defective O1 antigen or core oligosaccharide. By applying phage-binding studies, it was possible to distinguish between receptor mutants and mutations which probably caused abortion of later steps of phage infection. Furthermore, we investigated the genetic nature of O1-negative strains by Southern hybridization with probes specific for the O antigen biosynthesis cluster (rfb region). Two of the investigated O1 antigen-negative mutants revealed insertions of element IS1004 into the rfb gene cluster. Treating one wbeW::IS1004 serum-sensitive mutant with normal human serum, we found that several survivors showed precise excision of IS1004, restoring O antigen biosynthesis and serum resistance. Investigation of clinical isolates by screening for phage resistance and performing LPS analysis of nonlysogenic strains led to the identification of a strain with decreased O1 antigen presentation. This strain had a significant reduction in its ability to colonize the mouse small intestine.
Nesper
J
J
Zentrum für Infektionsforschung, Universität Würzburg, Germany.
Kapfhammer
D
D
Klose
K E
KE
Merkert
H
H
Reidl
J
J
D000327:Adsorption; D000818:Animals; D001435:Bacteriophages / Q000187:drug effects / Q000502:physiology*; D001483:Base Sequence; D002462:Cell Membrane / Q000648:ultrastructure / Q000821:virology; D002876:Chromosomes, Bacterial / Q000235:genetics; D004251:DNA Transposable Elements; D004768:Enterotoxins / Q000032:analysis / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D008969:Molecular Sequence Data; D011991:Receptors, Virus; D012703:Serotyping; D014734:Vibrio cholerae / Q000187:drug effects / Q000235:genetics / Q000502:physiology* / Q000821:virology
D004251:DNA Transposable Elements; D004768:Enterotoxins; D008070:Lipopolysaccharides; D011991:Receptors, Virus; C037420:stN protein, Vibrio cholerae