[Pathogenicity of Spiroplasma sabaudiense (mollicute) for the cells (c6/36) of Aedes albopictus (Insecta: Diptera) in vitro].

An initial stock of Spiroplasma sabaudiense had been maintained in cell-free medium for 2-3 years. Subsequent passages in Leibovitz's medium L-15 in the presence of Aedes albopictus (C6/36) cells dramatically increased the pathogenicity of S. sabaudiense towards these cells. Cytopathogenicity included production of syncytia, an increase in the number of mitochondria and alteration of their morphology, vacuolisation and a reduction in the rate of growth. Cell lysis was associated with cytadsorption by spiroplasmas and was apparent following the third passage. At six days post-inoculation during the fourth and fifth passages, cell cultures had been totally destroyed by S. sabaudiense. The intra-cellular stage of S. sabaudiense is described and the literature pertaining to the pathogenicity of spiroplasmas for insects is reviewed.