FIG 2.
PspA binds to LDH from dying host cell via Spn infection. (A) Recombinant His-tagged PspAWU2 protein was pulled down with purified host LDH-A and human lactoferrin. The bound proteins were separated by SDS-PAGE and visualized by Coomassie blue dye. This experiment was performed two times. (B) Human A549 type II pulmonary epithelial cells were infected with Spn strain TIGR4 for 4 h at an MOI of 100. Cultured medium was collected to measure percent LDH release when normalized to that from uninfected cells and total lysis using lysis buffer for 30 min. (C) Six- to eight-week-old C57BL/6 mice were challenged intratracheally with Spn TIGR4 (5 × 105 CFU) or mock infected with PBS. One day after pneumococcal challenge, relative levels of LDH in bronchoalveolar lavage fluid (BALF) samples were determined by ELISA. Means and standard errors are shown. Statistical analyses were performed using a Mann-Whitney U test.