Murine MBL-A and MBL-C. A and B, Viral neutralizing activity of purified native MBL-A and MBL-C against Phil82 (A) and Phil82BS (B). C and D, Viral neutralizing activity of mouse serum against Phil82 (C) and Phil82BS (D). Experiments were repeated at least twice. All data were combined and expressed as mean ± SE. *, p < 0.05. E, Lectin complement pathway activation activity. C4 deposition on virus was expressed as U/ml. Assays were performed in duplicate. WT, wild type; A/C, MBL-A/MBL-C null (= MBL null), A, MBL-A null, C, MBL-C null. Representative data of three experiments is shown. Assays were performed in triplicate and expressed as mean ± SE. *, p < 0.0001 against WT and MBL-C null. F, Thrombin-like activity. Same serum source as in Figure 2E. Assays were performed in triplicate and expressed as mean ± SE. *, p < 0.0001 against MBL null and MBL-C null. G, Presence of MBL in lungs. Western blot analysis of affinity purified MBL from BALF. mMBL, purified native serum murine MBL (1 μg) as a positive control. Each lane represents individual mouse. % volume for detected MBL bands was calculated as described in the materials and methods.