Consequently, the ‘cytokine storm’ that occurs to many viral infections, including influenza and SARS-CoV-2, will be associated with the induction of IDO/TDO/kynurenine/AhR activation and therefore wills alterations in the immune response and decreases in the serotonergic and melatonergic pathway. The gene discussed is AHR; the disease is viral infectious disease.