PLASMODIUM-GALLINACEUM - EFFECT OF INSECT CELLS ON OOKINETE DEVELOPMENT IN-VITRO

In vitro culture conditions affecting the transformation efficiency fr om zygote to ookinete for Plasmodium gallinaceum were examined, as a s tep toward improving the overall efficiency of in vitro culture system s for sporogonic stages. Gametocytes from infected chickens were allow ed to fertilize in vitro and the resulting zygotes were purified and c ultured. The time course for ookinete development in vitro was similar to that seen in Aedes aegypti mosquitoes. Supplementing a basal M-199 culture medium with heat-inactivated chicken serum and glucose did no t affect transformation efficiency, but resulted in a four-fold increa se in infectivity to mosquitoes when fed back to Ae, aegypti. Transfor mation from zygote to ookinete increased 5- to 10-fold when zygotes we re cocultured with one of six different mosquito cell lines or a Droso phila cell line. Under optimal conditions, transformation efficiencies of up to 75% were observed. The presence of insect cells also increas ed the longevity of ookinetes in culture up to 42 h, while in acellula r cultures ookinetes degenerated after about 24 h. Thr stimulatory eff ect was apparently not due to a factor secreted into the medium by the cells. (C) 1998 Academic Press.