FIG 4.
The REPEC ΔespZ strain does not expand in, and is rapidly cleared from, infected rabbits. The data shown are representative of a total of three independent animal studies, each performed with a minimum of eight animals per group on day 1. (A) The bacterial burden throughout rabbit infection with the parent WT strain, the ΔespZ mutant, or the ΔespZ mutant cis-complemented with REPEC espZ (espZ/espZR) or EPEC espZ (espZ/espZE) or in mock-infected animals was enumerated. Fecal pellets were collected from a minimum of three animals per group per day and plated onto medium selective for the infecting REPEC strain, as described in Materials and Methods. Data shown are average CFU per gram of fecal matter for each group of animals over time. (B) Bacterial burden data from panel A highlighting pathogen accumulation at the first (day 1) and last (day 7) time points following infection of rabbits with the parent WT strain, the ΔespZ mutant, or the ΔespZ mutant cis-complemented with espZ from REPEC (espZ/espZR) or EPEC (espZ/espZE). Data shown are average CFU per gram of fecal matter for each group of animals. (C) Enumeration of bacteria adherent to the cecum over time for rabbits infected with the parent WT strain, the ΔespZ mutant, or the ΔespZ mutant cis-complemented with REPEC espZ (espZ/espZR) or EPEC espZ (espZ/espZE). Ceca from euthanized animals were dissected, and REPEC bacteria were recovered as described in Materials and Methods. Data shown are average CFU per gram of cecal tissue for each group of animals. The limit of detection was 100 CFU/mg tissue. Since the number of animals in each group decreased variably over time due to the need to euthanize ill or moribund animals, statistical analyses were not performed on these data.