Growth of host cells and Chlamydia trachomatis in medium containing serum from 16-week-old calves.

We compared fetal bovine serum with five batches of serum from calves of various ages. HeLa and McCoy cells grown in only one batch of calf serum (from 16-week-old calves) had morphology, growth kinetics, and cloning efficiency similar to those of cells grown in fetal bovine serum. Cells maintained in calf serum from this batch supported the growth of two laboratory strains of Chlamydia trachomatis, a genital strain (E/UW-5/Cx) in McCoy cells and a lymphogranuloma venereum strain (440L) in HeLa cells. McCoy cells maintained in calf serum also supported the growth of C. trachomatis from clinical specimens. The batch of serum from 16-week-old calves was an effective alternative to fetal bovine serum for the growth of cells and of C. trachomatis. Other laboratories may be able to use calf serum for the maintenance of cells and for the isolation of Chlamydia spp. Before use, however, each batch of calf serum will have to be carefully evaluated to ensure that it is equivalent to fetal bovine serum.