The efficacy of recombinant feline interferon-omega in treating symptomatic cats infected with feline immunodeficiency virus



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PICO Question

In symptomatic cats with feline immunodeficiency virus (FIV), does high-dose subcutaneous recombinant feline interferon-omega (rFeIFN-ω) administration lead to reduced clinical signs compared to cats who were not administered rFeIFN-ω?


Clinical bottom line

Category of research



Number and type of study designs reviewed

Three studies were critically reviewed, including one randomised controlled trial, one non-randomised controlled trial, and one uncontrolled clinical trial.


Strength of evidence



Outcomes reported

Each of the studies reported that rFeIFN-ω administration significantly reduced clinical signs in FIV infected cats. However, all three papers have limitations in their study design and statistical analysis which lower the strength of the evidence they provide.



There is only weak evidence demonstrating that rFeIFN-ω administration leads to reduced clinical signs in FIV positive cats. Currently, there is a lack of well-designed, double-blinded, randomised, placebo-controlled clinical trials which have an adequate sample size and specifically focus on FIV positive cats. As a result, more robust evidence is needed to prove the definitive therapeutic benefit of rFeIFN-ω in symptomatic FIV patients. Treatment with rFeIFN-ω may still be considered by clinicians for cats with clinical signs potentially associated with retroviral infection, such as oral lesions and stomatitis, particularly if they are not responding well to supportive therapy alone.


How to apply this evidence in practice

The application of evidence into practice should take into account multiple factors, not limited to: individual clinical expertise, patient’s circumstances and owners’ values, country, location or clinic where you work, the individual case in front of you, the availability of therapies and resources.

Knowledge Summaries are a resource to help reinforce or inform decision making. They do not override the responsibility or judgement of the practitioner to do what is best for the animal in their care.


Beczkowski, P.M., Litster, A., Lin, T.L., Mellor, D.J., Willett, B.J. & Hosie, M.J. (2015). Contrasting clinical outcomes in two cohorts of cats naturally infected with feline immunodeficiency virus (FIV). Veterinary Microbiology. 176(1–2), 50–60. DOI:

de Mari, K., Maynard, L., Sanquer, A., Lebreux, B. & Eun, H. (2004). Therapeutic Effects of Recombinant Feline Interferon-co on Feline Leukemia Virus (FeLV)-Infected and FeLV/Feline Immunodeficiency Virus (FIV)-Coinfected Symptomatic Cats. Journal of Veterinary Internal Medicine. 18(4), 477–482. DOI:

Doménech, A., Miró, G., Collado, V.M., Ballesteros, N., Sanjosé, L., Escolar, E., Martin, S. & Gomez-Lucia, E. (2011). Use of recombinant interferon omega in feline retrovirosis: From theory to practice. Veterinary Immunology and Immunopathology. 143(3–4), 301–306. DOI:

Dunham, S.P. & Graham, E. (2008). Retroviral Infections of Small Animals. Veterinary Clinics of North America: Small Animal Practice. 38(4), 879–901. DOI:

Gerlach, N., Gibbert, K., Alter, C., Nair, S., Zelinskyy, G., James, C.M. & Dittmer, U. (2009). Anti-retroviral effects of type I IFN subtypes in vivo. European Journal of Immunology. 39(1), 136–46. DOI:

Gil, S., Leal, R.O., Duarte, A., McGahie, D., Sepúlveda, N., Siborro, I., Cravo, J., Cartaxeiro, C. & Tavares, L.M. (2013). Relevance of feline interferon omega for clinical improvement and reduction of concurrent viral excretion in retrovirus infected cats from a rescue shelter. Research in Veterinary Science. 94(3), 753–763. DOI:

Gil, S., Leal, R.O., McGahie, D., Sepúlveda, N., Duarte, A., Niza, M.M.R.E. & Tavares, L. (2014). Oral Recombinant Feline Interferon-Omega as an alternative immune modulation therapy in FIV positive cats: Clinical and laboratory evaluation. Research in Veterinary Science. 96(1), 79–85. DOI:

Leal, R.O. & Gil, S. (2016). The Use of Recombinant Feline Interferon Omega Therapy as an Immune-Modulator in Cats Naturally Infected with Feline Immunodeficiency Virus: New Perspectives. Veterinary Sciences. 3(4), 32. DOI:

Matsumoto, H., Teshima, T., Iizuka, Y., Sakusabe, A., Takahashi, D., Amimoto, A. & Koyama, H. (2018). Evaluation of the efficacy of the subcutaneous low recombinant feline interferon-omega administration protocol for feline chronic gingivitis-stomatitis in feline calicivirus-positive cats. Research in Veterinary Science. 121, 53–58. DOI:

White, J., Stickney, A. & Norris, J.M. (2011). Feline Immunodeficiency Virus: Disease Association Versus Causation in Domestic and Nondomestic Felids. Veterinary Clinics of North America: Small Animal Practice. 41(6), 1197–1208. DOI:

Vol. 8 No. 3 (2023): The third issue of 2023

Section: Knowledge Summaries

Categories :  Small Animal  /  Dogs  /  Cats  /  Rabbits  /  Production Animal  /  Cattle  /  Sheep  /  Pig  /  Equine  /  Exotics  /