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

Abstract

Specific treatments for the long-life infections by feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are either toxic, expensive or not too effective. Interferon α (IFN-α) is an immunomodulatory molecule which has been shown in vitro to decrease the release of infective particles. The aim of this study was to follow the progress of the clinical score and viral parameters of FeLV- and FIV-naturally infected privately owned cats treated with recombinant human IFN-α (rHuIFN-α, Roferon-A). Twenty-seven FeLV-infected cats (FeLV+) and 31 FIV-infected cats (FIV+) were enrolled in the study. Owners were instructed to orally administer 1 mL/day of 60 IU rHuIFN-α/mL in alternating weeks for four months. Blood samples were taken at the beginning of the study (M0), mid-treatment (M2), end of treatment (M4), and 6–10 months later (M10). Clinical status at these time points improved notably with rHuIFN-α treatment, regardless of the initial severity of the disease, an effect which lasted throughout the study in most animals (15 of the 16 FeLV+ symptomatic cats; 20 of the 22 FIV+ symptomatic cats) improved markedly their clinical situation. In FeLV+ cats plasma antigenemia (p27CA), reverse transcriptase (RT) activity, and proviral load decreased at M2 and M4 but increased again at M10 (“rebound effect”). The level of antigenemia or RT activity was below the detection limits in FIV+ cats, and the effect on proviral load was less marked than in FeLV+ cats. Taken together, these results indicate that rHuIFN-α is a good candidate for treating FeLV+ cats, but the “rebound effect” seen when treatment was discontinued suggests that additional studies should be conducted to clarify its effect on progression of the infection in cats.

Clinical and Hematological Follow-Up of Long-Term Oral Therapy with Type-I Interferon in Cats Naturally Infected with Feline Leukemia Virus or Feline Immunodeficiency Virus

“…In this study, we followed-up the disease in each cat by comparison to M0, before the start of the treatment. This approach has been followed by other researchers when studying naturally infected cats [20,[25][26][27][28], who have suggested that values at M0 are potentially more representative than a placebo in studies in field conditions with animals in unknown and probably different stages of infection. In addition, a placebo-treated or non-treated group of cats would have been ethically controversial, as owners demand a therapeutic option for their cats.…”

“…Animal handling, treatment, reagent manipulation, and data collection were all carried out in compliance with guidelines for Good Clinical Practice, and Good Laboratory Practice of the Animal Welfare Committee of the Veterinary Clinical Hospital and the Complutense University, and the experimental procedures were approved by the Institutional Animal Care and Use Committee of the Complutense University [20].…”

“…However, approximately one-third of the cats were asymptomatic ( Table 1). The laboratory findings and viral parameters in this group of cats at M0 is published elsewhere [4,20,23]. Though owners had been instructed to bring their cat to all three visits, for different reasons several failed in this obligation and some data were missing.…”

“…Several studies reported the effect of rHuIFN-α, mainly in FeLV-infected cats (reviewed in [9,19]). In general, these studies associate the effect of this cytokine with decreased mortality [17], improvement in the clinical signs, laboratory alterations, CD4+/CD8+ ratio, and viral parameters of FeLV+ cats treated with IFN-α [18,20]. Very few studies describe results of treatment with rHuIFN-α in FIV infection, but they seem to be similar to those reported for FeLV infection, though no significant effects of rHuIFN-α were observed with respect to viral and proviral load [20,21].…”

“…In general, these studies associate the effect of this cytokine with decreased mortality [17], improvement in the clinical signs, laboratory alterations, CD4+/CD8+ ratio, and viral parameters of FeLV+ cats treated with IFN-α [18,20]. Very few studies describe results of treatment with rHuIFN-α in FIV infection, but they seem to be similar to those reported for FeLV infection, though no significant effects of rHuIFN-α were observed with respect to viral and proviral load [20,21]. The aim of the present study was to analyze the progress of the clinical status, biopathological markers, and CD4+/CD8+ ratio in FeLV-and FIV-naturally infected cats during oral treatment for four months with rHuIFN-α and several months after treatment discontinuation, as it is not known whether changes in these parameters are long-lasting.…”