Members of the genus Mycoplasma are the smallest organisms that are capable of self-replication. They are known to cause various diseases as well as myriad problems in tissue culture. Incidence of mycoplasma contamination in cell culture has been reported to be somewhere between 5 per cent and16 per cent, depending on the source. Given the scope of mycoplasma infection, it is prudent for researchers to take precautions to avoid it, and when infection is suspected, to confirm and eliminate the infection as soon as possible.
Mycoplasma infection can cause morphological changes, pH reduction, metabolic problems, slow growth, and agglutination. Additionally, contamination can affect virus production and induce chromosomal changes. DNA rearrangements are a particular concern to cytogeneticists who may make erroneous diagnoses based on false positive results. Many times mycoplasma infections are insidious and do not destroy the host cells. Effects of contamination can build cumulatively, thereby making immediate detection less likely.
Because of their extremely small size (0.2 mm0.8 mm) and lack of rigid cell wall, mycoplasma may escape the sterile filtration process. Prevention measures, including good aseptic technique, use of primary cells when possible, and the wearing of protective clothing by technicians, should be routine in all cell culture laboratories.
Cell lines should be regularly tested for contamination. There are many methods for mycoplasma detection available today, including agar isolation, Hoechst staining, PCR, and immunodetection. For those who are unable or unwilling to discard their culture once infection is confirmed, methods of elimination should be considered.
Mycoplasma removal Agent (MRA) is a water-soluble oxo-quinoline-carboxylic acid derivative available in sterile, ready-to-use form. It is highly effective in eliminating mycoplasma from tissue culture. MRA actively kills a variety of species, including cultured and awild-type' by inhibiting mycoplasma DNA gyrase. MRA has been found to have a 95 per cent success rate; most cultures requiring the recommended concentration of 0.5 mg/ml. Some cultures may require higher dosages depending on the strain and severity of infection. ICN's MRA has been found superior to all other methods of mycoplasma elimination and is endorsed by the European Collection of AnimalCell Cultures.
The reagent is safe for all cell lines, does not affect chromosomal arrangement or antibody production,and shows results in less than sevendays. It is stable at room temperature.
MRA is an effective option for researchers who have detected an infection in a valuable cell line. Despite the high incidence of mycoplasma contamination in tissue culture laboratories, the many problems caused by these organisms can be curtailedwith preventative measures and an effective elimination reagent suchas MRA. u
ENQUIRY No 34
ICN Biomedicals Inc is based in Irvine, Calfiornia, USA. www.icnbiomed.com
