Figure 3.

Anti–hepatitis C virus (HCV) neutralizing antibody (nAb) titers are stable during chronic HCV monoinfection but decline after incident human immunodeficiency virus (HIV) infection. The 50% inhibitory dose (ID₅₀) titers of nAb against a heterologous HCV isolate (H77) were measured in serum samples isolated from 28 HCV-infected subjects before and after incident HIV infection. Titers were also measured in 10 HCV-monoinfected control subjects at 2 longitudinal time points. Gray lines represent titers for individual subjects measured at 2 time points; black lines, medians. Any nAb titers below the level of detection were assigned an ID₅₀ value of 1:25 for comparison analysis. Wilcoxon signed rank test was used to calculate significance of changes; when normality was satisfied, paired t tests were used.