EFFECT OF 3'AZIDO-2',3'-DEOXYTHYMIDINE (AZT) ON EXPERIMENTAL FELINE IMMUNODEFICIENCY VIRUS-INFECTION IN DOMESTIC CATS

The compound 3'azido-2),3 '-deoxythymidine (AZT) inhibits the replicat ion of feline immunodeficiency virus (FIV) in cell culture, and treatm ent with the compound has been reported to induce some clinical improv ement in some cases of feline FIV infection. In order to determine the effect of prophylactic treatment with AZT on experimental FIV infecti on, cats were treated,vith the compound at 0.2, 1.0, 5, 25 or 50 mg kg (-1) day(-1) for 29 days. One day after the treatment was started, the y were inoculated with 150 cat infectious doses of FIV. All the cats b ecame viraemic, seroconverted and developed lymphadenopathy, although the onset of each was delayed in the cats given higher doses of AZT. A naemia developed in the cats given high doses of AZT. Virus re-isolate d from the cats given 50 mg kg(-1) day(-1) was as susceptible to AZT i n cell culture as the inoculated virus. Thus AZT is much less effectiv e in cats than might have been expected from the results of in vitro s tudies.