Optic nerve involvement in viral spread in herpes simplex virus type 1 retinitis.

Colchicine was used to block fast axonal transport of the optic nerve of the uninjected eye after uniocular anterior chamber inoculation of herpes simplex virus type 1 (HSV-1). The results of these experiments suggest that second-wave virus is transported to the retina of the uninjected contralateral eye through the optic nerve of the uninjected eye, since intravitreal treatment with colchicine reduced both the viral titer and prevalence of animals with histopathologic evidence of retinitis. The chemical block to viral entry provided by colchicine was both dose- and time-dependent, with administration of colchicine that was timed to interfere with the second viral wave being the most effective. Colchicine did not appear to be directly inhibitory to viral replication or toxic to the virus, and colchicine did not cause clinical or microscopic evidence of retinal inflammation. Intravitreal injection of colchicine did not alter the timing or recovery of the first wave of virus.