COVID-19 Vaccination Induces Cross-Reactive Dengue Antibodies with Altered Isotype Profiles and In Vitro ADE.

Dengue virus is a mosquito transmitted flavivirus that cause inapparent or mild disease but can also cause severe hemorrhagic fever in humans. Cross-reactive IgG antibodies can cause under specific conditions antibody dependent enhancement (ADE) of the infection via Fc-receptor interaction. Antibodies from SARS-CoV-2 (anti-S) causing COVID-19 disease can also cross-react against the dengue envelope (anti-E). We therefore investigated the antibody profile of these cross-reactive antibodies and their ability to induce ADE. We found that the cross-reactive anti-E in COVID-19 vaccinated are dominated by IgM/A while, anti-S from vaccinated or anti-E from dengue infected patients have an IgG1 dominated antibody profile. The low-level anti-E IgG from COVID-19 vaccinated are dominated by low Fc-affinity IgG2/4 subclass. These antibodies were able to induce in vitro ADE stronger than from Dengue infected for the 1st,2nd dose of the vaccine or later omicron variant booster. This could partially be explained that ADE was inhibited by the complement system in dengue infected but not in COVID-19 vaccinated.