In vitro T cell function by domestic cats and cheetahs to two common pathogens, feline herpesvirus-1 (FHV-1) and Cryptococcus neoformans, was assessed. Conjunctival and oropharyngeal swabs were collected and a questionnaire regarding signalment, lifestyle, vaccination history and clinical signs was obtained for each cat. Results Exposure of CRFK cells to lactoferrin prior to or during viral adsorption inhibited FHV-1 replication by 87–96% (mean: 91%). Constant concentrations of interferon products were maintained throughout the study. Mice inoculated with a lysate of Sf9 cells expressing FHV-1 gD induced antibodies with virus-neutralizing and hemagglutination-inhibition activities. A 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide assay was used to detect cytotoxic effects of interferon. RESULTS: All cats developed acute conjunctivitis and rhinitis typical of FHV-1 infection.
Treatment with rFeIFN-omega at various concentrations resulted in significant reductions in the number of plaques (100,000 U/mL, 54.7%; and 500,000 U/mL, 59.8%) and in plaque size (100,000 U/mL, 47.5%; 250,000 U/mL, 81.0%; and 500,000 U/mL; 70.5%). Using recombineering, an FHV-1 mutant lacking the entire open reading frame encoding glycoprotein C (gC) was constructed based on the FHV-1 BAC clone. None of the tested concentrations of interferon caused significant cellular toxicosis. At some of the higher concentrations, the antiviral effect of rFeIFN-omega was greater than the antiviral effect of rHuIFN-alpha2b. Cytotoxicity assays were performed once to assess drug toxicity to CRFK cells.