FIG. 3.

Comparison between the one-dilution and endpoint methods of the CDC assay for measuring antibodies to JEV NS1 in horse sera. Percentages of specific cell lysis obtained by the one-dilution method were compared to NS1 antibody titers obtained by the endpoint method. Dotted lines indicate cutoff values for differentiating positive from negative samples. In the one-dilution method, 4.32% specific cell lysis was calculated from the averages and standard deviations obtained with negative samples; in the endpoint method, titers of 1:10 or higher were determined to be positive.