Figure 2

Growth kinetics within Balb/c mice after quadruple intravenous infection with EGDe::pIMC3 derivatives. (A) A tail vein injection with L. monocytogenes isolate EGDe was administered into 15 Balb/c mice with a total inoculum of 2 × 10⁴ CFU per 100 μl. The inoculum was composed of an equal ratio of EGDe wt (5 × 10³ CFU) tagged with the four different pIMC3 plasmids. On each subsequent day, 5 mice were sacrificed, with the spleens and livers enumerated on different BHI agars as described in the materials and methods. Bars correspond to EGDe; green (::pIMC3kan), red (::pIMC3ery), grey (::pIMC3tet) and blue (::pIMC3gus). Data are presented as mean CFU with standard deviation from five organs. The relative virulence ratio (RVR) (B) was calculated from the data presented in (A). Per mouse, the proportion of each strain comprised within the organ (liver or spleen) (output %) was divided by the proportion of the strain in the initial inoculum (input %) and presented as an individual data point (using the formula in additional file 2). The mean RVR was calculated from the average of 5 organs from each strain. A value of 1 indicates no change in the relative ratio. Symbols correspond to EGDe; green circle (::pIMC3kan), red diamond (::pIMC3ery), grey triangle (::pIMC3tet) and blue square (::pIMC3gus). (C) A tail vein infection with L. monocytogenes isolate EGDe was administered into 15 Balb/c mice with a total inoculum of 2 × 10⁴ CFU per 100 μl. The inoculum was composed of EGDe wt tagged with pIMCkan (0.75%), pIMCery (2.75%), pIMCtet (13.25%) and pIMCgus (83.25%) in a skewed ratio. The number on each bar gives the mean percentage for each strain recovered from the spleen or liver. Bars correspond to EGDe; green (::pIMC3kan), red (::pIMC3ery), grey (::pIMC3tet) and blue (::pIMC3gus).