Experimental anterior uveitis after subcutaneous injection of feline sarcoma virus

Feline sarcoma virus (FeSV) is a naturally occurring virus that causes spontaneous tumors in cats. The immunologic and morphologic characteristics of these tumors have been studied extensively. It was recently observed in experiments undertaken to induce systemic malignancy with this virus, that severe uveitis and clinical blindness occurred. An investigation of the ophthalmologic changes was undertaken. A fulminent anterior uveitis was produced in cats by a series of subcutaneous injections of live FeLV-FeSV. This intraocular inflammation occurred in five of six animals using high viral titers, and four of seven with lower titers, resulting from the freeze thaw process. On histopathologic examination, most animals demonstrated dysplastic changes of the ciliary body in addition to the iridocyclitis. The remainder of the eye was unaffected. These animals developed systemic tumors unaccompanied by local inflammation, many of which spontaneously regressed. Notable features of this potential model for uveitis are that (1) direct injection into the eye is unnecessary, and (2) intravenous administration inducing immune tolerance with antigenic overload presented to the spleen is avoided. This inflammatory reaction seems to be specific to the iris and ciliary body. Levels of live virus detected in the aqueous humor exceeded those in the serum. These results suggest that the virus may be actively secreted by the ciliary epithelium, or may preferentially proliferate within the eye.