ALN has differential activity on cells from various mammalian species. (a) The specific activities of ALN were determined by incubation of dilutions of His-ALN with erythrocytes from different host species. Results are an average of at least three independent experiments conducted in duplicated and error bars represent standard deviation. (b) The species selectivity of ALN was compared to ILY and PLO in hemolysis assays using human (square), horse (triangle), and pig (inverted triangle) erythrocytes. Representative of two experiments conducted in triplicate and error bars represent standard error of the mean. (c) Dilutions of His-ALN were added to cultured host cells and the amount of ALN required to reduce the cell viability by 50% was determined using the CellTiter 96® Aqueous One Solution Cell Proliferation Assay (Promega). Error bars indicate one standard deviation from the mean calculated from the averages of at least three independent experiments conducted in triplicate.