Experimental cytomegalovirus ophthalmitis.

Cytomegalovirus can produce a severe necrotizing chorioretinitis in patients on immunosuppressive therapy and infants born with congenital cytomegaloviral inclusion disease. To study the effect of cytomegalovirus on the eye, murine cytomegalovirus was injected into the eyes of nonimmunosuppressed Swiss CD-1 weanling mice. The eyes were then prepared for virus titer, as well as light and electron microscopy at variable periods after inoculation (1 to 28 days). From days 2 to 6, the hallmarks of cytomegalovirus infection, intranuclear and intracytoplasmic viral inclusions, were evident within cytomegalic cells. The major site of reaction was in the uveal tract, where necrosis and inflammation were prominent. Viral particles budding through the nuclear membranes into the perinuclear cisternae and vacuoles with viral particles could be seen in the cytoplasm of infected cells. In lesions older than 2 weeks, only a mild mixed inflammatory infiltrate and fibrosis were observed. Morphologic alterations unaccompanied by inflammation occurred in the outer sensory retina overlying infected retinal pigment epithelial cells. Multiple necrotic foci with inclusion-bearing cells in the liver indicated the systemic spread of virus from the eye. The titer of virus recovered from the eye peaked at day 4 and then declined to low levels, but infectious virus could still be isolated at day 28, even though viral particles were not seen morphologically at or after day 14. Many of the alterations seen in the model resemble those found in the human cytomegaloviral ophthalmitis.