The Salmonella serovar Enteritidis Sdf I region is located on the chromosome. Lane 1, total DNA amplified with rplI primers (343-bp amplicon); lane 2, total DNA amplified with the Sdf I primers (293-bp amplicon); lane 3, total DNA amplified with the spvC primers (565-bp amplicon); lane 4, plasmid preparation treated with exo-DNase amplified with rplI primers; lane 5, plasmid preparation treated with exo-DNase and amplified with Sdf I primers; lane 6, plasmid preparation treated with exo-DNase and amplified with spvC primers. Lanes 7, 8, and 9 are the same as lanes 4, 5, and 6, respectively, but without exo-DNase treatment before amplification. Strain CAHFS-285 (phage type 4) was used for these experiments.