Comparison of ViaB regions of Vi-positive organisms.

We cloned the vipR genes from Salmonella paratyphi C, S. dublin, and Citrobacter freundii strains and compared them with the S. typhi sequence to clarify the genetic relationship of the ViaB regions of Vi-positive organisms. ViaB regions were divided into two groups based on their sequences, the Salmonella and C. freundii groups. The vipR coding sequences of the Salmonella group were identical. Southern blot hybridization results using the full-length ViaB region as a probe support these findings.