Severe P berghei malaria influences plasma VWF multimer composition. (A) Plasma VWF multimer distribution during the course of malaria infection was assessed by nonreducing agarose gel electrophoresis. Typical multimer gels from example mice are presented. From day +3 following P berghei infection, abnormal UL-VWF multimers were consistently observed in murine plasma. Densitometric scanning of multimer gels was also performed, with individual panels corresponding to each lane. The horizontal axis is optical density. Abnormal UL-VWF multimers are present from day +3 through day +5 (highlighted by bands beyond the arbitrary red line) that are not present before P berghei infection. (B) Plasma ADAMTS13 activity levels were measured by FRETS-VWF73 proteolysis assay. All assays were performed in triplicate, and results represent the mean values. NS, not significant. (C) Typical Giemsa-stained peripheral blood film from a WT C57BL/6J mouse at day +5 following P berghei infection. Infected erythrocytes and thrombocytopenia are evident, but there are no significant features of microangiopathic hemolytic anemia. AU, arbitrary unit; HMW, high molecular weight; LMW, low molecular weight.