Mycoplasmas in Tissue Culture

Mycoplasmas are frequently found as contaminants in tissue-cultured cells. Infections may be inapparent or cause severe cytopathic changes. The source of primary contaminations in most cases is probably the upper respiratory tract of man. The wide dissemination of infections in cultures most probably occurs as a result of aerosols set up during the processing of contaminated cultures. Mycoplasmas in cultured cells may cause chromosome aberrations, degradation of the host cell DNA, and morphological transformations. They cleave thymidine and its related structural inhibitors and also degrade arginine. They inhibit the growth of adenovirus and Rous sarcoma virus and no doubt affect others. A number of antibiotics which are relatively non-toxic for cells in culture are active against mycoplasmas and may be used to cure infected cells. Mycoplasmas interfere with the biochemistry of the cell at many points and no one working with tissue cultures can afford to ignore them. Stringent aseptic techniques are the best safeguard against primary infections and cross-contaminations.