Besnoitia besnoiti: quantitative in vitro studies.

Experimental parameters for optimization of the growth conditions of Besnoitia besnoiti endozoites in vitro are presented. A combination of Hepes-buffered McCoy and Leibovitz (ML) medium with 10% bovine serum was preferable to Eagle's Minimum Essential Medium (MEM) based on either Hank's or Earle's salts. The ML medium and a CO2 balanced gas phase significantly increased the growth rate of the parasite. Infection of Vero cells at 1 h after subcultivation resulted in higher yields of endozoites than infection of 24- or 48-h-old cells. Increased numbers of parasites (6 x 10(7) and 9 x 10(7)) in the infection inoculum per Roux bottle containing Vero cells produced poor yields, while infection with 2 x 10(7) parasites resulted in a 250 to 300-fold increase after 6 days of cultivation with one medium change.