Feline Immunodeficiency Virus Lacks Sensitivity to the Antiviral Activity of Feline IFN- γ

Abstract

The antiviral activity of recombinant feline interferon-γ (rFeIFN-γ) against feline immunodeficiency virus (FIV) was investigated. A persistently FIV_Bang-infected feline T cell line (FeT-J/Bang) was treated with either rFeIFN-ω, rFeIFN-γ, or recombinant human IFN-α2 (rHuIFN-α2), and the culture fluids were tested for antiviral activity by reverse transcriptase (RT) assay. FeT-J/Bang cell cultures treated with rFeIFN-ω showed dose-dependent inhibition of RT activity. In contrast, rFeIFN-γ treatment had no antiviral effect on FIV replication but instead caused a statistically significant enhancement on day 9 of culture. Antiviral activity of rFeIFN-γ was also tested on feline peripheral blood mononuclear cells (PBMC). PBMC cultures were inoculated with FIV_Bang and simultaneously treated with either rFeIFN-ω, rFeIFN-γ, or rHuIFN-α2. FeIFN-γ had no effect on FIV replication, unlike the rFeIFN-ω and rHuIFN-α2, which had strong anti-FIV effects. In another study, rFeIFN-γ treatment was initiated 3 days before FIV_Bang infection, the day of FIV_Bang infection, or 3 days post-FIV_Bang infection and then tested for antiviral activity. The time of initiating rFeIFN-γ treatment had no effect on the antiviral activity. Hence, these results suggest that unlike rHuIFN-α2 and rFeIFN-ω, rFeIFN-γ has no inhibitory effect on FIV replication in PBMC but causes a slight enhancement in a feline T cell line.