Figure 8. Normal mice are protected from intra-nasal challenge with SCHU S4 by passive transfer of sera from levofloxacin protected mice.

Mice were challenged intra-nasally with SCHU S4 and then treated with levofloxacin at either 24 hours post-infection (6.25 mg/kg body weight) or at 72 hours post-infection (40 mg/kg/body weight), as described in Figures 1 and 2. Thirty days following intra-nasal challenge, mice were sacrificed and sera obtained. Serum was also obtained from control mice, not challenged with SCHU S4. Sera from mice were pooled and then used for passive transfer into normal mice. Normal, naïve, mice were then given 250 μl of serum from either control mice or from mice challenged with SCHU S4 and treated with levofloxacin at 24 vs 72 hours post challenge. Four hours after the transfer of sera, mice were challenged with 5 LD₅₀ doses (172 CFU) of SCHU S4. Mice were monitored twice daily for up to one month. Asterisk indicates statistically significant survival with p<0.0005