Effects of interferon-alpha on cytopathic changes and titers for feline herpesvirus-1 in primary cultures of feline corneal epithelial cells.

Objective: To assess the effect of interferon (IFN)-alpha on viability of feline corneal epithelial cells, replication of feline herpesvirus (FHV)-1, and virus-induced cytopathic changes.

Sample Population: Healthy eyes from 10 recently euthanatized cats.

Procedure: 4 replicate primary cultures of feline corneal epithelial cells were grown after the addition of 10(2) to 10(6) IU of IFN-alpha/mL. Cultures were examined every 24 hours for evidence of cytotoxic changes. Viable cell counts and percentage of viable cells were determined 48 hours after initiation of culture. In a separate experiment, cultures of corneal cells were inoculated with FHV-1 and cultured for 72 hours with or without 10(5) IU of IFN-alpha/mL. The FHV-1-infected cultures were evaluated for viral-induced cytopathic effects, and viral titers were determined in samples of culture supernatant.

Results: Interferon-alpha did not have cytotoxic effects on corneal epithelial cells at concentrations ranging from 10(2) to 10(6) IU of IFN-alpha/mL. Interferon-alpha at a concentration of 10(5) IU/mL significantly reduced the cytopathic changes and FHV-1 titers.

Conclusions And Clinical Relevance: Lack of in vitro cytotoxic effects and efficacy against FHV-1 infection in primary cultures of feline corneal cells suggests that the in vivo therapeutic effect of IFN-a should be assessed in controlled clinical trials.