INCREASING THE YIELD OF EIMERIA-TENELLA OOCYSTS IN PRIMARY CHICKEN KIDNEY-CELLS

The present study was undertaken to increase the yield of Eimeria tene lla oocysts in primary chicken kidney cells (PCKCs) using a comparativ ely inexpensive cell-culture system. PCKCs growing on coverslips posit ioned on the bottoms of individual wells in 24-well tissue-culture pla tes were infected with sporozoites of E. tenella. The effects of chang ing the culture medium (RPMI 1640), medium pH, serum type, and serum c oncentration in the wells were determined by counting newly produced o ocysts at 7 days postinoculation. There were significantly more (P < 0 .01) oocysts produced when the medium was supplemented with 10% fetal bovine serum (FBS) and changed either daily or every other day compare d with nor changing the medium. When the same medium was changed daily , significantly more (P < 0.05) oocysts were produced at pH 7.4 than a t pH 8.0 but not at pH 6.0. If the medium was changed daily, significa ntly more (P < 0.05) oocysts were produced when medium was supplemente d with 10% FBS only rather than 5% and 10% chicken serum. The cell-cul ture system described in this study offers a convenient and efficient method for investigating the biological, biochemical, and immunologica l relationships between E. tenella and the host cell.