It has been confirmed that CTSL helps contain pathogenic infections as reflected with higher mortality and lung burdens of Mycoplasma pulmonitis or orthomyxovirus influenza A in CTSL-/- mice and exacerbated leishmaniasis in mice treated with specific inhibitor of CTSL, while the dissemination and colonization of Edwardsiella tarda was suppressed in Japanese flounder with overexpressed CTSL [18, 28, 61]. The gene discussed is CTSL; the disease is influenza.