EFFECT OF CONDITIONED MEDIA FROM CHICKEN AND TURKEY INTESTINAL-CELL CULTURES ON INVASION BY SPOROZOITES OF 3 SPECIES OF AVIAN COCCIDIA

The effect of conditioned media from cultures of turkey and chicken in testinal cells on cellular invasion by sporozoites of avian Eimeria sp ecies was examined in vitro. Media conditioned by the growth of cells from the ceca, mid-intestine (area of the yolk stalk diverticulum), an d duodenal loop were examined for their ability to enhance invasion. C onditioned medium from cultures of turkey cecal cells significantly en hanced invasion by the turkey coccidia Eimeria adenoeides, by 2.4-fold , and E. meleagrimitis, by 2.2-fold, as compared with invasion in the presence of control medium. Conditioned medium from mid-intestinal cel l cultures enhanced invasion by the two coccidial species by 2.0- and 2.1-fold, respectively. The enhancement occurred with conditioned medi a from early (1) as well as later (11) passages of cells. This suggest s that the enhancing factor was produced by fibroblast-like cells, the predominant cell type at both early and late passages, and not by epi thelial like cells that had disappeared by the first or second passage . Additionally, conditioned media from cultures of chicken cecal and d uodenal loop cells significantly enhanced invasion by the turkey cecal coccidium, E. adenoeides, (1.7- and 1.6-fold, respectively). This was less enhancement than was caused by the turkey cell conditioned media . Heat treatment (56 degrees C for 45 min) of conditioned media failed to alter the effect on invasion. Neither the turkey or chicken cecal cell media nor conditioned media from any other chicken intestinal cel l cultures enhanced invasion by E. tenella, the chicken cecal coccidiu m. Although morphologically dissimilar when they were first plated, th e gross appearance and growth of the turkey and chicken cells when con ditioned media was collected was comparable.