During the secondary infection, cases P1 and P2 displayedsecondary immune responses with an increase in serum antibody titers: for example, case P1RBD-IgM increased from 1 : 10 to 1 : 2560, NP-IgM from 1 : 20 to 1 : 80, and NP-IgG from1 : 640 to 1 : 2560 (Figs 1c and S3, Table S3). The gene discussed is CD40LG; the disease is infection.