ASS1 and Salmonella Infections: As NO radicals are produced by iNOS from arginine with ornithine as a reaction by-product, enzymes allowing recycling of ornithine back to arginine, i.e. argininosuccinate synthase (ASS1) and argininosuccinate lyase (ASL1), are also induced in inflamed tissues and in chicken monocytes and macrophages following Salmonella infection [12].