FIG 1.

Effect of gtr modifications on S. Typhi O-antigen. (A) Expression of the family 3 gtr operon leads to recognition by O12₂ serum. LPS was prepared as described in Materials and Methods and run on a Tricine–SDS-PAGE gel. Blots were probed with commercial OMA serum (top) and O12₂ serum (bottom). B, STy-Basal; WT, S. Typhi parent strain BRD948 (“wild type”); Ac, STy-Acetyl; G, STy-Gluc; FM, STy-FM; Oag, O-antigen. (B) Summary of results from chemical analysis of S. Typhi BRD948 O-antigen. OAc, acetate. (C) Schematic of the O-antigens of engineered strains used in these studies. See Fig. S1 in the supplemental material for additional silver stain analysis of the S. Typhi O-antigen.