VIRUS-RNA PERSISTS WITHIN THE RETINA IN CORONAVIRUS-INDUCED RETINOPATHY

The murine coronavirus, mouse hepatitis virus (MHV), JHM strain, induc es a biphasic retinal disease in adult BALB/c mice. In the early phase , Day 1 to Day 7, a retinal vasculitis is noted which is associated wi th the presence of viral proteins and infectious virus. In the late ph ase, Day 10 to Day 140, a retinal degeneration is associated with the absence of viral proteins, infectious virus, and inflammatory cells. T he purpose of this study was to determine if viral RNA persists within the retina during the retinal degenerative phase of the disease. BALB /c mice were inoculated by the intravitreal route with 10(4.0) TCID50/ 5 mu l of virus. The presence of viral RNA was detected by in situ hyb ridization with a viral cDNA probe and viral proteins were identified by immunocytochemical staining. During the acute phase of the infectio n, viral RNA was found in the retina, RPE, ciliary body epithelium, an d the iris epithelium. During the late phase of the infection, viral R NA was almost exclusively found within the retina and RPE and not in t he anterior segment of the eye. Within the retina, viral RNA was detec ted in the ganglion cell layer, the inner retina, the outer retina, an d the RPE cell. Immunocytochemical staining identified viral protein w ithin the retina only from Day 1 to Day 8, This ocular disease was als o associated with a persistent systemic infection. Both viral RNA and viral proteins were identified within the liver during the first 8 day s. However, only viral RNA was detected in the liver from Day 8 to Day 60. These studies demonstrate that MHV established an acute infection (Day 1-8) where infectious virus and viral proteins were identified. This was followed by a persistent infection within the retina and live r where only viral RNA were detected by in situ hybridization. (C) 199 6 Academic Press, Inc.