Cytomegalovirus retinitis during AIDS: Current issues and future directions

Cytomegalovirus (CMV) retinitis is the leading cause of blindness in patients with acquired immune deficiency syndrome (AIDS). Before improved therapeutic approaches can be developed to manage this devastating sight- threatening disease, specific questions pertinent to the pathophysiology of CMV retinitis must be addressed. These questions relate to the origin of virus responsible for retinitis, spread of virus within the retina, the immunopathogenesis of retinal destruction, and the fate of virus during traditional antiviral therapy. In this review, we examine for each question the clinical rationale, the experimental data, and the clinical implications associated with these data. In particular, two experimental systems are emphasized. One is an in vitro system to study the susceptibility of human retinal pigment epithelium to CMV infection. The other involves clinically- relevant murine models of CMV retinitis, especially one of retrovirus- induced immunodeficiency (MAIDS). We suggest that immune-based therapy alone or in combination with traditional chemotherapy offers improved prospects for maintaining subclinical CMV infection in the immunosuppressed individual, thereby preventing CMV retinitis.