Use of cycloheximide to study independent lipid metabolism of Chlamydia trachomatis cultivated in mouse L cells grown in serum-free medium.

A system for measuring chlamydial lipid synthesis was developed with mouse L cells grown in serum-free modified Waymouth 752/l medium in a shaker culture. Host lipid synthesis was reduced approximately 90% when cells were incubated for 24 h in medium containing cycloheximide (2 micrograms/ml). Lipid metabolism was monitored by measuring the incorporation of [3H]isoleucine into the total lipid of normal and infected cells. The results suggested that lipid synthesis of Chlamydia trachomatis lymphogranuloma venereum (LGV-404L) was not inhibited by cycloheximide treatment when the chlamydiae were grown in L cells, whereas host lipid synthesis was inhibited. Chlamydial lipid metabolism began about 6 to 12 h after infection when the noninfectious reticulate body was found and continually increased until the beginning of the appearance of intracellular infectious elementary bodies at 24 to 30 h.