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.
Highlights
Feline leukemia and feline immunodeficiency are two of the most important viral diseases affecting domestic cats
This study was conducted to analyze the effect of oral treatment with low doses of rHuIFN-α (Roferon-A) on the viral parameters of domestic cats naturally infected with feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV), since from our previous experience, we had observed that the clinical status of infected cats improved notably with IFN treatment
The results show that treatment with low doses of rHuIFN-α was associated with an improvement of the viral parameters studied in FeLV+ cats as long as the animals were treated, but reverted to levels similar to the original ones within 4–8 months upon treatment discontinuation
Summary
Feline leukemia and feline immunodeficiency are two of the most important viral diseases affecting domestic cats. FIV infections have been described to progress following several stages similar to HIV infection in humans, leading to a final stage with a severe immunodeficiency that predisposes to many secondary infections and, eventually, to the death of the cat. Even though there is a long clinical latency, there is some degree of FIV replication as antibodies are detectable early after infection and remain during all the life of the cat [2]. These antibodies are mostly against the main protein of the capsid, p24CA, and their detection constitutes the basis for serological diagnosis. Some are triggered by the envelope proteins (gp95SU and gp40TM), and their induction is used for a partially successful vaccine [3]
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