Mycoplasma strain 163K was isolated from the gills of a tench (Tinca tinca L.) with red disease. The cells are elongated, ovoid or flask shaped, consisting of a thicker body and a more slender part ending in a hemispherical terminal structure, that is apparently stabilized by a cytoskeleton. They are able to attach to inert surfaces and living cells. The most exciting property of the organisms is their fast gliding motion, which occurs on glass and plastic surfaces and which is not interrupted by resting periods. Growth occurs between 17 and 30°C, with an optimum at 25"C, in modified Hayflick medium with horse or bovine serum and in medium with swine serum. Acid is produced from several carbohydrates, but arginine and urea are not catabolized. The organism reduces tetrazolium chloride, produces film and spots and hydrogen peroxide, and is able to hemolyze and to adsorb to erythrocytes of several animal species. Indirect immunofluorescence test, growth inhibition, and metabolism iqhibition tests indicate that the mycoplasma represents a new species for which the name Mycoplasma mobile is proposed. Strain 163K (ATCC 43663) is the type strain.In a study of 85 fish of several species, mycoplasmalike colonies were obtained on agar plates directly inoculated with unfiltered organ material of 16 of the 85 fish examined (17). Despite immense efforts, cultivation in further passages was only possible in one case, with an isolate from the gills of a tench (Tinca tinca L.). In a second study of 95 fish of several species (unpublished data), again mycoplasmalike colonies were observed repeatedly on agar plates directly inoculated with materials from the gills, skin, spleens and intestines, of the fish, but subcultivation did not succeed in any case. Consequently, there was only one type of mycoplasma isolated from these fish. However, this mycoplasma distinguished itself by such unique properties that its description as a new species appears to be justified. MATERIALS AND METHODSMycoplasma. The mycoplasma isolate originated from the gdls of a tench showing symptoms of red disease. Growth was obtained under aerobic conditions at an incubation temperature of 15°C on modified Hayflick medium. The details of primary isolation have been described previously (17). The isolate was designated strain 163K.Media and cultivation. Strain 163K was isolated and generally cultivated in Hayflick medium (7), modified as described before (17). For the preparation of antisera rnycoplasmas were cultivated in Friis medium (13), modified as described before (17). For the preparation of solid medium, 0.7% (wthol) purified agar (Oxoid no. 1) and 0.01% dextran were added. Strain 163K was usually incubated aerobically at 25°C. For determination of the temperature range enabling growth and reproduction, mycoplasmas were incubated at 4, 17, 25, 30, and 37°C. Strain 163K was filter cloned three times according to the recommended procedure, using a 220-nm-pore membrane filter (Millipore C o p ) (23).Growth curves. Broth medium (5 ml) was inoculated with...

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.

The intracerebral inoculation of newborn Syrian hamsters with pure cultures of Spiroplasma sp. strain SMCA caused severe, prolonged disease involving the central nervous system, culminating in death. The disease was characterized by spasms, muscular tremors, disturbances in motor control, inability to feed, dramatic loss of weight, and runting. The effect was dose related, with the largest numbers of viable spiroplasmas producing the highest incidence of disease and death in the shortest period of time. Severe hemorrhaging developed throughout the brain, liver, and spleen, and spiroplasmas were readily recovered from these organs, indicating that the agent disseminated from the initial site of infection to distant host tissues. Newborn animals were susceptible, but adults were resistant; these findings are similar to those reported for newborn mice and rats. Unlike mice and rats, hamsters did not develop cataracts visible to the unaided eye. The histopathological features of eye disease in hamsters were different from those in rats and were characterized by microophthalmia (especially in runted hamsters) and abnormal proliferation, disorientation, and disorganization of corneal, lens, and retinal tissues. The significance of these findings is discussed.

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