Ethidium bromide-stained agarose gel of PCR-amplified DNA from Y. ruckeri in trout tissues. Lane 1, Y. ruckeri CECT 4319; lane 2, 1-kb plus DNA ladder (Amersham); lanes 3 to 5, DNA from kidney, liver, and spleen homogenates from intraperitoneally inoculated trout, respectively; lanes 6 and 7, 8 and 9, and 10 and 11, DNA from kidney, liver, and spleen homogenates from naturally infected trout, respectively; lanes 12 to 14, DNA from kidney, liver, and spleen homogenates from noninoculated trout, respectively.