A trial with 3′-azido-2′,3′-dideoxythymidine and human interferon-α in cats naturally infected with feline leukaemia virus

Abstract

Feline leukaemia virus (FeLV) infection is still one of the leading causes of infection-related deaths in domestic cats. Treatment with various drugs has been attempted, but none has resulted in cure or complete virus elimination. Human interferon-α2a (huIFN-α2a) and 3′-azido-2′,3′-dideoxythymidine (AZT) have been proven to decrease antigenaemia in cats infected experimentally with FeLV. The purpose of this study was to assess the efficacy of huIFN-α2a, AZT and a combination of both drugs in cats infected naturally with FeLV in a placebo-controlled double-blinded trial. Fourty-four FeLV-infected cats in which free FeLV p27 antigen was detected in serum by enzyme-linked immunosorbent assay were included in the study. Cats were assigned to one of four treatment groups that received either high dose huIFN-α2a (10 5 IU/kg q24h; 12 cats), AZT (5 mg/kg q12h; 10 cats, both of these treatments (12 cats) or placebo (10 cats). All cats were treated for 6 weeks. Clinical variables, including stomatitis, and laboratory parameters, such as CD4 + and CD8 + counts and serum FeLV p 27 antigen concentration, were recorded throughout the treatment period. No significant difference among the groups was observed during the treatment period for any of the parameters. Aside from anaemia in one cat treated with AZT, no adverse effects were observed. It was not possible to demonstrate efficacy of huIFN-α2a or AZT alone or together in cats infected naturally with FeLV when given according to this regimen for 6 weeks; however, no notable side effects were detected.

Follow-Up of Viral Parameters in FeLV- or FIV-Naturally Infected Cats Treated Orally with Low Doses of Human Interferon Alpha

“…As a molecule active in many cellular types of different species, rHuIFN-α has several advantages over rFeIFN-ω [12]. The antiviral activity of IFN-α is well-documented, and has been described to reduce in vitro the amount of viral infective particles of FeLV and FIV in feline cell cultures, without affecting the synthesis of viral proteins [13,14], though results in vivo are controversial [15]. In addition, rHuIFN-α is non-toxic, low-cost and easy to administer orally.…”

Efficacy of antiviral chemotherapy for retrovirus-infected cats

“…46 In a placebo-controlled, doubleblind study in naturally FeLV-infected cats using a similar high dose regimen, treatment with IFN-α (1 x 10 5 IU/kg SC q24h for 6 weeks) did not lead to a significant improvement in clinical, laboratory, immuno logical or virological parameters (EBM grade I). 47 Low dose oral IFN-α was used in a placebocontrolled study in experimentally induced FeLV infection; 0.5 IU/cat (eight cats) or 5 IU/cat (five cats) was given (following experimental challenge) on 7 consecutive days on alternate weeks for a period of 1 month. 111 No difference was found in the development of viraemia between groups; however, treated cats had significantly fewer clinical signs and longer survival times when compared with the placebo group (with a better response in the cats given 0.5 IU/cat) (EBM grade II).…”

“…45,46 In a study in which cats naturally infected with FeLV were treated with zidovudine for 6 weeks, however, treatment did not lead to a significant improvement in clinical, laboratory, immunological or virological parameters (EBM grade I). 47 Thus, overall therapeutic efficacy of zidovudine is less promising in FeLV-infected cats than in FIV-infected cats.…”

Virus de la leucemia felina: un patógeno actual que requiere atención en Colombia

“…Los fármacos antivirales empleados en medicina humana, tales como la 3'-azido-2', 3'-didesoxitimidina (AZT), han sido utilizados contra el FeLV con resultados poco concluyentes. Varios estudios en los cuales se ha tratado a gatos infectados de forma natural por FeLV con AZT y dosis altas de interferón-α humano subcutáneo, han mostrado que, a pesar de no evidenciarse efectos adversos de estas terapias solas o en combinación, los tratamientos con AZT y/o interferón-α humano no conducen a ninguna mejora estadísticamente significativa en los parámetros clínicos, de laboratorio o virológicos comparados con grupo control tratado con placebo (Hartmann et al, 2002;Stuetzer et al, 2013). Por otro lado, se ha demostrado la actividad anti-FeLV de cuatro fármacos aprobados por la FDA (Food and Drug Administration de los EE.UU) in vitro en cultivos celulares, en concentraciones terapéuticas no tóxicas (tenofovir, raltegravir, decitabine y gemcitabina).…”