Previous studies detected immunoreactivity against proteins of a human A-type retroviral particle type-I (HIAP-I) in serum samples from the majority of patients with Graves' disease (autoimmune hyperthyroidism). To determine whether hyperthyroid cats might be a model for retroviral involvement in thyroid autoimmunity, serum samples from 32 cats (21 hyperthyroid and 11 controls) and 10 hypothyroid dogs were examined for immunoreactivity with HIAP-I using a Western blot technique. Of the 21 hyperthyroid cats 15 (71.4%) were HIAP-I positive, while only 2 of 11 (11.8%) control animals without endocrine pathology were positive. No significant correlations were seen between HIAP seroreactivity and serum thyroid hormone levels (T3 and T4), age, gender, treatment history, vaccination status, or weight. No seroreactivity to HIAP-I was detected in hypothyroid dogs. An examination of HIAP-I reactivity in feline leukemia virus (FeLV)-seroconverting cats found that 7/9 (78%) animals viremic for FeLV-A showed an alteration in HIAP serology, whereas only 1/7 (14%) nonviremic animals showed a change in HIAP-I serology. Results suggest that cats serve as a useful animal model for the role of retroviruses in thyroid autoimmune diseases.

Reference: Sander et al, Microsc Res Tech 68:235-238, 2005.