The expression of IgM (ighm), which was used as a marker for B cells, remained relatively constant in both infected and dexamethasone-treated fish (Fig. S5F), whereas tgfb1b, a marker for regulatory T cells (Tregs), was suppressed upon infection in the immunocompetent fish (P=0.0007), and upregulated in the dexamethasone-treated group (P=0.03) (Fig. S5G). The gene discussed is IGHM; the disease is infection.