Objective—To establish optimal conditions for long-term culture of the erythrocytic stage of Theileria uilenbergi.
Sample Population—Red blood cells from 3 splenectomized sheep experimentally infected with a blood stabilate of T uilenbergi.
Procedures—Cultures of T uilenbergi were initiated by use of blood from experimentally infected sheep collected when parasites were detected in Giemsa-stained thin blood smears. Different culture conditions were tested to optimize in vitro growth of the organisms. Subcultures were performed at a ratio of 1:2, 1:4, and 1:8 when the percentage of parasitized erythrocytes (PPE) was at least 1% or when the initial PPE was doubled.
Results—The optimal culture medium was HL-1 medium (a complete chemically defined medium) supplemented with 20% sheep serum and 0.75% chemically defined lipids. Optimal culture conditions included incubation in a humidified 2% O2, 5% CO2, and 93% N2 atmosphere at 37°C. Cultures of the merozoite stage of the parasite were continuously propagated in vitro for > 1 year. The PPE reached values of up to 3%.
Conclusions and Clinical Relevance—Optimization of culture conditions to reach a high PPE seems worthwhile. The continuous propagation of T uilenbergi in culture allows the production of parasite material without infecting animals and provides a continuous laboratory source of parasites for further studies.