CD40LG and severe acute respiratory syndrome: In a study conducted by Hsueh et al. (2004)26 to evaluate the chronological evolution of IgM, IgA, and IgG antibodies after SARS-CoV infection using immunofluorescent antibody assays, it was found that seroconversion for IgG occurred on average at 10 days, simultaneously or one day before IgM and IgA, which had an average seroconversion of 11 days.