Possible role of HHV-6 in the development of AIDS retinitis

Majority of AIDS patients experience visual loss due to AIDS-associated retinitis or commonly known as CMV retinitis. It has been reported that CMV infection of the retina is a late manifestation of AIDS and a poor prognostic sign. The etiology and mechanism(s) involved in the development of AIDS-associated retinitis is currently unknown. It is of critical importance to understand the pathobiology of this disease process in order to develop a rational approach to therapeutic intervention. We have determined the frequency and proximity of simultaneous occurrence of HIV-1 and HHV-6 in retinal tissues of AIDS patients in the absence of CMV infection. Active infection of HIV-1 has been identified in the retinal tissues of 30-60% of AIDS patients analyzed. HHV-6 antigens and transcripts were detectable in about 50% of HIV-1 positive retinas. Most significant finding of our studies is the presence of HIV-1 and HHV-6 antigens and transcriptional activity in retinal tissue in the absence of CMV infection. These observations suggest that HIV-1 in association with HHV-6 may predispose certain retinal cells to other opportunistic agents such as CMV in late stages of AIDS-associated retinitis.