AHR and viral infectious disease: For the aryl hydrocarbon receptor (AhR), a transcription factor that is activated by endogenous and exogenous compounds (e.g., bilirubin, biliverdin, metabolites from the essential amino acid L-tryptophan, environmental pollutants (like dioxins), some drugs, and microbial metabolites), mainly known for its role in detoxifying environmental pollutants, its functions have recently been established in other physiological processes, including the cellular cycle and differentiation, lipid and carbohydrate metabolisms, as well as the control of the immune system in viral infections [26,27].