Pathogenicity of Spiroplasma sp. strain SMCA in rabbits: clinical, microbiological, and histological aspects

Newborn rabbits inoculated intracerebrally with early-passaged broth cultures of Spiroplasma strain SMCA (suckling mouse cataract agent) either died or developed eye disease. Death occurred 4 to 12 days after infection. Rabbits which died showed hemorrhages throughout the brain, especially in areas leading to the optic nerve, and hemorrhages in the liver. SMCA could be reisolated from brain, liver, and eyes. Rabbits with eye disease did not open their eyes during an observation time of 3 to 4 months. Pathological examination revealed marked microophthalmia and severe cataract formation characterized by complete degeneration of lens fibers and liquefaction and mineralization of the lens. Other ocular changes were chronic panophthalmitis with complete destruction of the retina. Neither eye disease nor death could be induced by inoculating SMCA subcutaneously into newborn rabbits. In adult rabbits, no disease occurred after intravenous or subcutaneous injection or after inoculation into the conjunctival sac.