The increased levels of TGFβ-switched IgG2b anti-CHIKV Ab on d16 post-infection of O mice (S3G Fig) led us to hypothesize that anti-CHIKV immunity in O mice is improperly coordinated and that excessive production of TGFβ contributes to increased CHIKVD in O mice. The gene discussed is TGFB1; the disease is infection.