In the first 2 days of the infection early interferon signaling was present, leading to increased IRF1, IFN-α and IFN-β expression in lung tissue and, at day 1, a significant increase was detected of the expression of the retinoic acid-inducible gene 1 (RIG-1), an intracellular receptor involved in the identification of RNA viruses (63). This evidence concerns the gene IFNB1 and infection.