Afucosylation of anti-dengue IgG is associated with enhanced susceptibility to dengue virus infection postvaccination.

Dengue viruses (DENVs) cause 390 million infections annually, although only ~25% of these infections are symptomatic. Whereas antibody features linked to severe DENV disease are well studied, factors influencing infection susceptibility remain less clear. Here, we examined immunoglobulin G (IgG) characteristics before and after DENV vaccination (Dengvaxia) in individuals with a history of prior DENV exposure, comparing those who developed postvaccination infections to those who remained infection free. Elevated anti-DENV afucosylation, present before or after vaccination, was associated with increased likelihood of infection after vaccination. These data were further supported by mechanistic studies, which revealed that nonneutralizing, afucosylated, post-Dengvaxia IgG enhanced DENV replication in mice. This enhancement was dependent on CD16, the receptor for the afucosylated IgG Fc domain. Together, these findings support a model in which the presence of afucosylated IgG promotes virus replication, increasing the likelihood of productive infection upon DENV exposure. Moreover, these results highlight that IgG1 fucosylation is a predictor of risk for breakthrough DENV infection despite vaccination and support the importance of investigating strategies to regulate Fc fucosylation during vaccination.