Antigen-specific IgG glycosylation profiles in hamsters and macaques following COVID-19 vaccination.

Vaccination triggers the production of antigen-specific antibodies, including IgG. IgG molecules are glycosylated at the Fc region, and these glycan modifications markedly influence Fc receptor binding and downstream immune functions. Notably, infections with enveloped viruses such as SARS-CoV-2 can trigger the production of afucosylated IgG, which enhances FcγRIIIa binding and promotes antibody-dependent cellular cytotoxicity. Despite its importance, the glycosylation profiles of antigen-specific IgG following vaccination remain understudied, particularly in animal models. In this study, we investigated the Fc glycosylation patterns of antigen-specific IgG in hamsters and rhesus macaques following immunization with Ad26.COV2.S COVID-19 vaccine. Overall, our findings demonstrate that IgG Fc glycosylation dynamics in these animal models largely parallel those in humans. For example, we observed a transient afucosylated IgG response in both species, resembling the response previously reported in humans. These results indicate that IgG Fc glycosylation responses to vaccination in macaques and hamsters recapitulate key features of the human response, supporting their use as translational models for adenovirus vector-based vaccination studies.