Objective: To assess the effect of cidofovir on viability of feline corneal epithelial (FCE) cells, replication of feline herpesvirus (FHV)-1, and virus-induced cytopathic changes.
Sample population: Healthy eyes from 14 recently euthanatized cats.
Procedure: Cidofovir at concentrations ranging from 0.05 to 0.000005 mg/mL was added to primary cultures of FCE cells, and cytopathic changes and effects on cell proliferation and cell viability were determined during the subsequent 48 hours. Efficacy of cidofovir (0.02 and 0.05 mg/mL) to prevent in vitro infection of FCE cells with FHV-1 was determined during 72 hours of culture by assessing viral cytopathic effects and viral titers.
Results: Cidofovir at concentrations of 0.05, 0.005, and 0.0005 mg/mL significantly reduced mean viable cell counts, and cidofovir at a concentration of 0.05 mg/mL significantly reduced the percentage viability of cultured FCE cells. Minimal cytopathic changes were observed at concentrations of 0.02 and 0.05 mg of cidofovir/mL. Cidofovir at concentrations of 0.05 and 0.02 mg/mL abrogated the cytopathic effects attributable to FHV-1 infection and reduced viral titers from > or =10(14) TCID(50)/mL to < or =10(3.5) TCID50/mL.
Conclusions and clinical relevance: Cidofovir in vitro was highly efficacious against FHV-1 infection of a primary culture of FCE cells but had cytostatic effects on cultured cells.