OPTIC-NERVE MORPHOMETRY FOLLOWING AXONAL DEGENERATION FROM SAIDS IN RHESUS-MONKEYS

In order to further study AIDS (acquired immunodeficiency syndrome) re lated neuropathologic findings, specifically progressive diffuse leuko -encephalopathy (PDL) and optic neuropathy, ten macaque monkeys (Macac a mulatta) were infected with simian immunodeficiency virus (SIV), obs erved for varying periods, and then sacrificed and tissue prepared for analysis. A marked difference from human AIDS pathology was found: in all monkeys, there was significant peripheral axonal dropout, as oppo sed to relatively little dropout in the central areas of the nerves (t stat. = -5.9, p <.001). In those monkeys infected with SIV for over o ne year, the axonal loss in the periphery was also greater than in the central optic nerve (t stat. = -5.03, p <.001); monkeys infected with SIV for less than one year had slightly less peripheral than central loss (t stat. = -4.5, p =.001). When compared with humans, however, it was found that the overall loss of axons was less (15% in monkeys vs. up to 45% in humans). There was also a lack of discernible retinal pa thology, such as cotton wool spots, in the monkey tissue.