The goals of this study were to 1) determine the pathogenicity of the FAdV-4 ON1 isolate in specific pathogen free (SPF) chickens, 2) investigate virus dissemination in tissues, virus titers in cloacal swabs, and antibody response, and 3) examine the dynamics of interferon (IFN)-γ, interleukin (IL)-10, IL-18, and IL-8 gene expression after FAdV-4 ON1 infection. This evidence concerns the gene IL18 and infection.