Leprosy in a chimpanzee. Morphology of the skin lesions and characterization of the organism.

Microscopic features of lepromatoid lesions in a chimpanzee inoculated with bovine leukemia virus consisted of diffuse dermal infiltrations of foamy histiocytes, except for a subepidermal "clear zone" devoid of infiltrating cells. Acid-fast organisms were in histiocytes, dermal nerves and a branch of the left radial nerve. The organisms were more intensely acid-fast with the Fite-Faraco than with the Ziehl-Neelsen stain. The organisms did not oxidize 3,4-dihydroxyphenylalanine (dopa) to indole but their acid-fast staining quality was removed by pretreatment with pyridine. Human leprosy patients, inoculated simultaneously with chimpanzee and human lepromin, reacted similarly to both lepromins. Organisms, when inoculated into mouse footpads, multipllied in 6 months to a quantity that was compatible with their identification as Mycobacterium leprae.