Isolation of the Trachoma Agent in Cell Culture.

Summary Five isolates of the trachoma agent have been made by culture in irradiated McCoy cells, without use of the standard method of yolk sac inoculation. These have been passed serially in cell culture at intervals of 3-4, or at 5 days, 9 to 15 times. Increase in level of infection was indicated by increasing counts of inclusions observed regularly at 48 hours after inoculation, and by cytopathic effect in some passages. Passage of cell culture harvests to yolk sacs gave irregular results throughout the series with no indication that successful passage in cell culture was accompanied by adaptation to yolk sac. The technical assistance of C. Thomas Colonna, J. I. Thomas, and Richard Grays is gratefully acknowledged.