Chronic chikungunya is associated with decreased anti-CHIKV antibody titers, neutralizing capacity, and antibody-dependent cellular cytotoxicity

Figures

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  Figure 1. Assessment of anti-chikungunya antibody titers in chronic and non-chronic chikungunya patients at 3 and 6 months post-infection (A–D) Plasma samples from CHIKV-infected cases were analyzed at 3 and 6 months post-infection for anti-CHIKV IgM, anti-CHIKV IgG titers, anti-CHIKV E2 specific antibodies, and anti-CHIKV neutralizing antibodies. (E–H) Comparison of anti-CHIKV IgM, anti-CHIKV IgG titers, anti-CHIKV E2 specific antibodies, and anti-CHIKV neutralizing antibodies between chronic and non-chronic patients at the 6-month time point. Error bars represent median ± interquartile range. Paired (A–D) and unpaired (E–H) group analyses were performed using the non-paired Wilcoxon signed-rank and Mann-Whitney tests, respectively. (A–D: n = 16; E and F: no, n = 22; yes, n = 16.)

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  Figure 2. Assessment of ADCP and ADCD in chronic and non-chronic chikungunya patients at 3 and 6 months post-infection (A–D) Schematic overview of the ADCP and ADCD assays using plasma corrected for anti-CHIKV IgG titers (500 IgG ELISA units) (A and D).ADCP and ADCD in paired patient samples (n = 16) obtained at 3 and 6 months post-infection (B and C). (E and F) ADCP and ADCD measured at 6 months post-infection in patients with (n = 16) or without (n = 22) chronic chikungunya. Error bars represent median ± interquartile range. Paired and unpaired group analyses were performed using the non-paired Wilcoxon signed-rank and Mann-Whitney tests, respectively.

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  Figure 3. Assessment of ADCC in chronic and non-chronic chikungunya patients at 3 and 6 months post-infection (A) Schematic overview of the ADCC assay using plasma uncorrected for anti-CHIKV titers (plasma dilution 1:10). (B) ADCC assay readouts in paired patient samples (n = 16) obtained at 3 and 6 months post-infection. (C) ADCC assay measured at 6 months post-infection in patients with (n = 16) or without (n = 22) chronic chikungunya. Error bars represent median ± interquartile range. Paired and unpaired group analyses was performed using the non-paired Wilcoxon signed-rank and Mann-Whitney tests, respectively.

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  Figure 4. Assessment of ADNKA in chronic and non-chronic chikungunya patients at 3 and 6 months post-infection (A) Schematic overview of the ADNKA assay using plasma uncorrected for anti-CHIKV titers (plasma dilution 1:10). (B and C) Percentages of NK cells expressing CD107a and IFNγ in paired patient samples (n = 16) taken at 3 and 6 months post-infection. (D and E) Percentages of NK cells expressing CD107a and IFNγ at 6 months post-infection in patients with (n = 16) or without (n = 22) chronic chikungunya. Paired and unpaired group analyses were performed using the non-paired Wilcoxon signed-rank and Mann-Whitney tests, respectively.

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  Figure 5. Anti-CHIKV antibody titers and Fc-mediated effector functions in chikungunya patients stratified based on sex (A–K) Plasma samples in the cohort stratified based on sex as males (n = 20) and females (n = 18) were analyzed for anti-CHIKV IgM titers, anti-CHIKV IgG titers using qualitative ELISA, anti-CHIKV E2 quantitative ELISA, focus reduction neutralization assay (FRNT) for anti-CHIKV neutralizing antibodies, and effector function assays, i.e., ADCP, ADCD, ADCC, and ADNKA. (E) and (G) were performed with plasma corrected for anti-CHIKV IgG titers (500 IgG ELISA units). (F), (H), (I), (J), and (K) were performed using fixed-dilution plasma non-corrected for anti-CHIKV IgG titers. Error bars represent median ± interquartile range. Unpaired group analysis was performed using the Mann-Whitney test.

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  Figure 6. Correlation of anti-CHIKV humoral immune responses (A) Spearman correlation matrix showing anti-CHIKV antibody titers and antibody-mediated effector functions (using plasma uncorrected for anti-CHIKV titers; plasma dilution 1:10) measured at 6 months post-infection. Correlation coefficients (r values) are indicated by the color scale. Red and blue circles represent negative and positive Spearman correlation coefficients between two variables, respectively. The size of the circles represents the magnitude of the correlation coefficient. Statistical analysis was performed using the Spearman correlation test (∗p < 0.05, ∗∗p < 0.01).