However, the burdens observed in the galU mutant-infected mice were significantly lower (p < 0.01) in the spleens and livers (p < 0.001) of infected mice at the 96 h time point. Collectively, these results reveal that despite its normal replication/dissemination phenotypes, the galU mutant is more readily cleared than WT FT. Figure 3 Mutation of the galU gene does Blasticidin S not attenuate infectivity of FT in vivo. C57BL/6 mice (4/group) were infected intranasally with 5 × 104 CFU (50 × LD50 for FT LVS) of either the WT or galU mutant strain of FT LVS. Organs were harvested at 24, 48, 72 and 96 hours p.i.
and CFU/g of organ was determined for lungs, liver, and spleen. The lower limit of detection was 20 CFU/g. Statistical analyses were performed via two-way ANOVA with a Bonferroni
multiple comparisons post test and all significant differences are indicated as follows: ** P < 0.01 Epoxomicin mw and *** P < 0.0001. The data shown is representative of two independent experiments of similar design. Mutation of galU alters the kinetics of innate immune responses To determine whether differences in innate immune recognition of infection might be responsible for the dramatic difference in the outcome of disease with the galU mutant vs. WT FT, we analyzed the kinetics of immune cell infiltration into the lungs following infection. BALF were MK-2206 in vitro collected from each mouse at the time of sacrifice and a series of flow cytometric analyses was performed. The numbers of macrophages, dendritic cells, and NK cells recruited into the lungs of mice infected with the galU mutant and WT FT were similar at each time point (data not shown). However, higher numbers of neutrophils were observed in the lungs of mice infected with the galU mutant at the 24- and 48-hour time points, with peak numbers of neutrophils measured at 48 hours post-infection (Figure 4A). In contrast, Carnitine dehydrogenase the kinetics of recruitment of neutrophils into the lungs of mice infected with WT FT was much slower (Figure 4A), peaking five days post-infection (data not shown). Figure 4 Neutrophil recruitment
and chemokine expression in the lungs following infection with the galU mutant. C57Bl/6J mice (4/group) were infected intranasally with 5 × 104 CFU (or 50 × LD50) of either the WT or galU mutant strain of FT and BALF was collected from individual mice at 24, 48, 72 and 96 hours post-infection. Flow cytometric analyses were performed on the cells recovered from BALF to determine the numbers of neutrophils at each timepoint. Statistical analyses were performed via two-way ANOVA with a Bonferroni multiple comparisons post-test and statistically significant differences (P < 0.05) are indicated (*) (Panel A). The concentrations of KC, G-CSF, MIG, and IL-10 (Panel A) and TNF-α, MIP-1α, MIP-1β, MIP-2, and MCP-1 (Panel B) in BALF at the 24 and 48 hour time points, respectively, were determined using a Luminex multiplex kit. Statistical analyses were performed using unpaired t tests.