Researchers around the world are working intensively to find a safe and effective treatment for feline infectious peritonitis (FIP), a highly lethal systemic disease, but to date no such treatment has become available for practical use. The etiologic agent in FIP is a coronavirus, an enveloped, single-stranded positive-sense RNA virus. Not all feline coronaviruses, however, cause FIP; only the feline infectious peritonitis virus (FIPV) biotype is the agent involved in FIP. The other feline coronavirus biotype, feline enteric coronavirus (FECV), causes a mild, often subclinical, enteritis. Both feline coronavirus (FCoV) biotypes exist as two serotypes, type I and II; therefore, there are FECV types I and II and FIPV types I and II. The majority of FCoVs worldwide, approximately 70-90%, belong to type I.
Previously these authors determined that type I FCoV has a close association with cholesterol throughout its life cycle, and that itraconazole, a highly lipophlic, triazole antifungal drug often used to treat dermatophytosis and other fungal infections in cats, inhibits FCoV infection. Itraconazole has been reported to inhibit intracellular cholesterol transport, and the authors wanted to determine if this drug would inhibit intracellular cholesterol transport in feline cells. In the present study, the antiviral effects of itraconazole on FCoV were studied in cell cultures of feline cells found to be sensitive to types I and II FIPV and type II FECV. Three strains of type I FIPV and one strain of type II FIPV were used in the study.
Results of the study showed that itraconazole inhibits type I FCoV infection in feline cells, but had no effect on Type II FCoV infection. Based on the known pharmacokinetics of itraconazole in cats, and the results obtained with various concentrations of the drug in cell cultures evaluated in the present study, the authors recommend using itraconazole for treatment of FIP following the currently recommended fungal infection treatment protocol in cats. The authors plan to perform a clinical trial of itraconazole in cats diagnosed with FIP, and also investigate combinations of itraconazole with other drugs in treatment of FIP. [PJS]