Application of SOFT analyses to “low” viral growth in unstimulated cervical tissue for donors 1 (a), 2 (b), and 3 (c) and % virus inhibition across donors (d). Data shown represent the viral growth in the absence (○; solid lines) or presence (dotted lines) of the candidate microbicide PRO 2000 (5 μg/ml [], 50 μg/ml [], and 500 μg/ml [▪]). Medians and interquartile ranges for replicate measurements are shown. The SOFT (↑) for donors 1 and 2 occurred at day 10, while that for donor 3 occurred at day 14. (d) Inhibition of viral infection determined using different endpoint analyses. The % virus inhibition results were compared for PRO 2000 (5, 50, and 500 μg/ml) for three donor cervical tissue explant tissue samples from one laboratory. Virus inhibition (%) was calculated using p24 measurements for (i) SOFT, (ii) day 10, and (iii) day 14 endpoint analyses. The median and interquartile ranges across replicates and donors are shown. Virus inhibition for each treatment was compared to that for the Ba-L control at SOFT, day 12, and day 14 (Wilcoxon signed-rank test; *, P < 0.05; **, P < 0.01).