In vitro comparison of antiviral drugs against feline herpesvirus 1

K van der Meulen¹ , B Garré¹^,2 , S Croubels² and H Nauwynck¹

¹Laboratory of Virology

²Department of Pharmacology, Pharmacy and Toxicology, Faculty of Veterinary Medicine, Salisburylaan 133, Ghent University, 9820 Merelbeke, Belgium

author email corresponding author email

BMC Veterinary Research 2006, 2:13doi:10.1186/1746-6148-2-13


Published:	26 April 2006

Abstract

Background

Feline herpesvirus 1 (FHV-1) is a common cause of respiratory and ocular disease in cats. Especially in young kittens that have not yet reached the age of vaccination, but already lost maternal immunity, severe disease may occur. Therefore, there is a need for an effective antiviral treatment. In the present study, the efficacy of six antiviral drugs, i.e. acyclovir, ganciclovir, cidofovir, foscarnet, adefovir and 9-(2-phosphonylmethoxyethyl)-2, 6-diaminopurine (PMEDAP), against FHV-1 was compared in Crandell-Rees feline kidney (CRFK) cells using reduction in plaque number and plaque size as parameters.

Results

The capacity to reduce the number of plaques was most pronounced for ganciclovir, PMEDAP and cidofovir. IC_{50 (NUMBER)}values were 3.2 μg/ml (12.5 μM), 4.8 μg/ml (14.3 μM) and 6 μg/ml (21.5 μM), respectively. Adefovir and foscarnet were intermediately efficient with an IC_{50 (NUMBER)}of 20 μg/ml (73.2 μM) and 27 μg/ml (140.6 μM), respectively. Acyclovir was least efficient (IC_{50 (NUMBER)}of 56 μg/ml or 248.7 μM). All antiviral drugs were able to significantly reduce plaque size when compared with the untreated control. As observed for the reduction in plaque number, ganciclovir, PMEDAP and cidofovir were most potent in reducing plaque size. IC_{50 (SIZE)}values were 0.4 μg/ml (1.7 μM), 0.9 μg/ml (2.7 μM) and 0.2 μg/ml (0.7 μM), respectively. Adefovir and foscarnet were intermediately potent, with an IC_{50 (SIZE)}of 4 μg/ml (14.6 μM) and 7 μg/ml (36.4 μM), respectively. Acyclovir was least potent (IC_{50 (SIZE)}of 15 μg/ml or 66.6 μM). The results demonstrate that the IC_{50 (SIZE)}values were notably lower than the IC_{50 (NUMBER)}values. The most remarkable effect was observed for cidofovir and ganciclovir. None of the products were toxic for CRFK cells at antiviral concentrations.

Conclusion

In conclusion, measuring reduction in plaque number and plaque size are two valuable and complementary means of assessing the efficacy of an antiviral drug. By using these parameters for six selected antiviral drugs, we found that ganciclovir, PMEDAP, and cidofovir are the most potent inhibitors of FHV-1 replication in CRFK cells. Therefore, they may be valuable candidates for the treatment of FHV-1 infection in cats.