PMC

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.

Anti–hepatitis C virus (HCV) envelope binding antibody titers are stable during chronic HCV monoinfection but decline after incident human immunodeficiency virus (HIV) infection. Titers of anti-HCV envelope (E1E2) antibody were measured in serum samples isolated from 27 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 line represents titers for individual subjects measured at 2 time points; black lines, medians. Enzyme-linked immunosorbent assay (ELISA) titers below the level of detection were assigned a titer of 1:25, and serum samples still ELISA positive at a 1:51 200 dilution were assigned that value for comparison analysis. Wilcoxon signed rank test was used to calculate significance of changes; when normality was satisfied, paired t tests were used.

Decline in anti–hepatitis C virus (HCV) neutralizing antibody (nAb) titers after incident human immunodeficiency virus (HIV) infection occurs in subjects with CD4⁺ T-cell loss. A–C, Anti-HCV nAb titers were stable after incident HIV infection in subjects with CD4⁺ T-cell counts >350/mm³, declined significantly in those with counts of 200–350/mm³, and trended downward in those with counts <200/mm³. Gray lines represents titers for individual subjects measured at 2 time points; black lines, medians. Any nAb titers below the level of detection were assigned a 50% inhibitory dose (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. D, Comparison of the change in nAb titers over time in HCV-monoinfected controls and HIV/HCV-coinfected subjects stratified by post-HIV CD4⁺ T-cell counts. Symbols represent changes for individual subjects; black lines indicate medians. Rank sum tests were used to calculate significance; when normality was satisfied, t tests were used.

Decline in anti–hepatitis C virus (HCV) envelope binding antibody titers after incident human immunodeficiency virus (HIV) infection occurs in subjects with CD4⁺ T-cell loss. A–C, Anti-HCV envelope titers were stable after incident HIV infection in subjects with CD4⁺ T-cell counts >350/mm³ but declined significantly in subjects with CD4⁺ T-cell counts of 200–350/mm³ or <200/mm³. Gray line represent titers for individual subjects measured at 2 time points; black lines, medians. Enzyme-linked immunosorbent assay (ELISA) titers below the level of detection were assigned a titer of 1:25, and serum samples still ELISA positive at a 1:51 200 dilution were assigned that value for comparison analysis. Wilcoxon signed rank test was used to calculate significance of changes; when normality was satisfied, paired t tests were used. D, Comparison of the change in binding antibody titers over time in HCV-monoinfected controls and HIV/HCV-coinfected subjects stratified by post-HIV CD4⁺ T-cell count. Symbols represent changes for individual subjects; black lines, medians. Rank sum tests were used to calculate significance; when normality was satisfied, t tests were used.

Breadth of the neutralizing antibody response declines after incident human immunodeficiency virus (HIV) infection. Serum samples isolated from 15 hepatitis C virus (HCV) –infected subjects before and after incident HIV infection were tested for their ability to neutralize 11 clonal heterologous genotype 1 HCV pseudoparticles (HCV_pp). Serum samples from 10 HCV-monoinfected control subjects at 2 longitudinal time points were used as controls. Gray lines represents number of HCV_pp neutralized (neutralizing breadth) for individual subjects measured at 2 time points; black lines, medians (overlapping lines are dithered for clarity). Positive neutralization of each of the HCV_pp was noted when neutralization was >25%, which was >2 standard deviations above the mean neutralization of negative control murine leukemia virus pseudoparticles by all 25 serum samples tested. Wilcoxon signed rank test was used to calculate significance of the change in number of HCV_pp neutralized; when normality was satisfied, paired t tests were used.

Decrease in anti hepatitis C virus (HCV) neutralizing antibody breadth after incident human immunodeficiency virus (HIV) infection occurs in subjects with CD4⁺ T-cell loss. A–C, The decrease in neutralizing breadth after incident HIV infection was not significant in subjects with CD4⁺ T-cell counts ≥350/mm³, but breadth declined significantly in subjects with counts <200/mm³. Grey lines represent number of HCV_pp neutralized (neutralizing breadth) for individual subjects measured at 2 time points; black lines, medians (overlapping lines are dithered for clarity). Positive neutralization of each of the HCV_pp was noted when neutralization was >25%, which was >2 standard deviations above the mean neutralization of negative control murine leukemia virus pseudoparticles by all 25 serum samples tested. Wilcoxon signed rank test was used to calculate significance of the change in number of HCV_pp neutralized; when normality was satisfied, paired t tests were used. D, Comparison of the change in the number of HCV_pp neutralized over time in HCV-monoinfected controls and HIV/HCV-coinfected subjects stratified by post-HIV CD4⁺ T-cell count. Symbols represent changes for individual subjects; black lines, medians. Rank sum tests were used to calculate significance; normality was satisfied, t tests were used.