USE OF MEROCYANINE-540 AND HOECHST-33258 FOR THE SELECTIVE KILLING OFCONTAMINATING MYCOPLASMAS IN CELL-CULTURES

Mycoplasma infection can substantially affect the biological propertie s of cells in vitro. We have devised a method for the selective killin g of mycoplasmas, e.g., A. laidlawii, M. fermentans, M. hyorhinis and M. arginini, from experimentally infected cell cultures. This approach is based on the differential binding of the lipophilic fluorescent pr obe Merocyanine 540 followed by illumination with visible light. The e fficiency of the procedure depends on the Merocyanine 540 concentratio n, the intensity of illumination, and the presence of oxygen in the me dium. When A. laidlawii contaminated corneal endothelial cell cultures were treated simultaneously with Merocyanine 540 and DNA-binding fluo rochrome Hoechst 33258 and then illuminated, a significant degree of e radication was observed, even after one cycle of treatment. This combi ned treatment is therefore recommended as an effective method of purgi ng mycoplasmas from contaminated cultures.