EFFECT OF CONDITIONED MEDIA FROM SEVERAL CELL-TYPES ON INVASION BY EIMERIA ADENOEIDES SPOROZOITES

The effect of conditioned media (media aspirated from a variety of cel l cultures after 4 d of growth) on cellular invasion by sporozoites of the turkey coccidium, Eimeria adenoeides, was examined. Conditioned m edium from turkey kidney cells and baby hamster kidney cells failed to alter invasion. However, conditioned medium from turkey cecal cell cu ltures produced a significant (P < 0.05), two-fold increase in invasio n over control medium in a variety of cell types. Retentates of condit ioned medium from the turkey cecal cells that were passed through micr oconcentrators having molecular mass cutoffs of 50, 100, and 300 kDa s imilarly enhanced invasion over retentates from control medium. Howeve r, retentates from microconcentrators with a cutoff of 1,000 kDa faile d to enhance invasion. Pretreatment in conditioned medium, followed by washing of sporozoites prior to inoculation into cultures, did not re sult in enhanced invasion. Moreover, when the interval between inocula tion of sporozoites into cells and fixation of cultures was reduced to less than 3 h, no enhancement of invasion occurred. Conditioned mediu m from turkey cecal cells that were grown in the presence of S-35-tran slabel had at least two labeled bands at 150 kDa and > 200 kDa that we re absent in conditioned media from turkey kidney and baby hamster kid ney cells.