The aim of this experiment is to determine the difference in protein expression, if any, in a mouse model of pneumococcal pneumonia using wild type and a polyamine transport operon deletion mutant strain of S. pneumoniae TIGR4, using expression proteomics. Eight week old female C57bl/6 mice were used in this study. The experimental design had two groups of 3 animals each that were administered 50 µL 1 X 107 CFU wild type S. pneumoniae TIGR4 or S. pneumoniae TIGR4 ΔpotABCD strain by intranasal instillation. The control group with three animals received 50 µL PBS. Mice were euthanized 4 hr and 12 hr post infection and lung tissues were harvested. The control group animals were euthanized 12 hr post infection.