Overexpression of IL-6 has been shown to promote chronic inflammation and increase susceptibility to viral infections.32,34,36,37 It is possible that excessive production of IL-6 in cats with FCGS explains the chronic FCV and PFFV infection and elevated globulin and acute-phase protein levels in blood typically found and may be directly involved in perpetuation of oral mucosal inflammation and ulceration. This evidence concerns the gene IL6 and viral infectious disease.