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

SIMPLE SUMMARY: The viruses which produce feline leukemia (FeLV) and feline immunodeficiency (FIV) attack cells involved in the immune response. As specific drugs are either nonexistent, produce secondary effects, or are expensive, a therapeutic possibility is using nonspecific immunostimulants, such as human interferon alpha. We used this drug to treat 27 cats infected by FeLV and 31 infected by FIV. All cats were naturally infected and treatment was administered orally by their owners for four months. Participating cats were evaluated in our clinics at mid-treatment (M2), end of treatment (M4), and 4–8 months after the end of treatment (M10). We observed that treatment was well tolerated by the cats (as it did not affect the liver or the kidney functions), and improved most of the parameters analyzed (clinic, anemia, white cell counts, and CD4+/CD8+ ratio) as long as it was administered. However, 4–8 months after it was discontinued, though most animals remained clinically healthy, many of these parameters had rebounded to initial values or values even worse than the initial values. Thus, more studies should be conducted with longer administration of this drug to evaluate tolerability and sustained improvement of diseases produced by these two viruses which may lead to death. ABSTRACT: Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV), two of the most important pathogens of cats, produce chronic systemic diseases with progressive death of cells involved in the immune response, ultimately leading to death. Immunostimulants is one of the few alternatives to the symptomatic treatment. In this study, 27 naturally FeLV-infected (FeLV+) and 31 naturally FIV-infected (FIV+) cats were administered orally by their owners 60 IU/day of recombinant human interferon alpha (rHuIFN-α) for four months in alternate weeks. Clinical status was evaluated and blood samples collected at four different visits or months (M): pretreatment (M0), mid-treatment (M2), end of treatment (M4), and 4–8 months after end of treatment (M10). Most cats ostensibly improved their clinical status, and many became asymptomatic. rHuIFN-α treatment improved the anemic processes observed at M0 (at least in cats with mild or moderate anemia) and leukocyte counts, including a more favorable CD4+/CD8+ ratio. An increase in the serum gammaglobulin concentration was seen in 80% of the cats. Despite observing an obvious favorable progress in the clinical, biopathological, and CD4+/CD8+ values during treatment, almost invariably all the parameters analyzed worsened after treatment discontinuation (M10), which suggests that the interferon-α protocol should be either extended or include additional cycles for a long-lasting benefit in FeLV+ and FIV+ cats.