Objective: To elucidate the tissue specificity of the expression of HIV-1 genes in an animal and its pathological effects on these tissues.
Design and methods: Transgenic mice carrying a defective HIV-1 genome were bred in order to overcome the host-range barrier of this virus.
Results: mRNA specific to the transgene was detected in the eyes and the spleen, and, in smaller quantities, in the thymus and the brain. Interestingly, many of the transgenic mice developed cataracts at 3-6 months of age. Swelling and vacuolation of the lens fiber cells were marked, but the epithelial cells of the lens were less affected. HIV antigens were detected in the lens fiber cells and the retina by immunological staining. Accumulation of large amounts of p24 Gag antigen was demonstrated in the affected lens by immunoblot analysis, while negligible Env or other viral proteins was detected. Although accumulation of the Gag protein was also detected in the skin and the brain, no apparent abnormality was observed in these tissues.
Conclusions: Preferential expression of the HIV genes in the eyes, skin, brain and lymphoid tissues was demonstrated. The accumulation of the Gag protein is suggested to have detrimental effects on lens fiber cells, causing cataracts.