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

Infection due to the chikungunya virus (CHIKV) can cause chronic disease characterized by persistent arthralgia. While the humoral immune response to CHIKV is well characterized, the contribution of Fc-mediated effector functions in disease pathogenesis remains poorly understood. We assessed the quantitative and qualitative aspects of CHIKV-specific antibodies in patients with self-resolving or chronic chikungunya, including IgG/IgM titers and effector functions such as antibody-dependent cell phagocytosis (ADCP), complement deposition (ADCD), cell cytotoxicity (ADCC), and NK cell activation (ADNKA). Anti-CHIKV IgG and IgM titers declined between 3 and 6 months post-infection, and the lower titers at 6 months were associated with the chronic disease. The ADCP and ADCD capacities were similar between patients with self-resolving or chronic chikungunya. Patients with the chronic disease showed reduced ADCC but no reduced ADNKA. Females exhibited higher anti-CHIKV E2 antibody concentrations and ADCP. This study provides a comprehensive overview of Fc-mediated effector functions in chikungunya patients with differential disease outcomes.