Feline coronavirus (FCoV) infections are common in cats. Infected cats may shed different levels of coronavirus in multi-cat environments, but the immune mechanisms responsible for this apparent difference are not known. In the same way, the manifestations of feline infectious peritonitis (FIP) are variable, and although a genetic predisposition has been demonstrated, little information about the role of the immune system is available. Alpha1-acid glycoprotein (AGP) is an acute-phase protein involved in the immune response that has a different behavior in cats with FIP compared to FCoV-infected non-symptomatic cats. In this project the researchers will investigate the relationship between the FCoV-shedding characteristics or the clinical appearance of FIP on one hand, and the presence of different forms of AGP on the other.