Amount of cholesterol in host membrane affects erythrocyte invasion and replication by Babesia bovis

Cholesterol is a major component of the erythrocyte membrane. In the present study, we investigated the effects of cholesterol reduction in host bovine erythrocytes (RBC) on the growth of Babesia bovis, a major bovine haemoprotozoon. An in vitro growth assay with bovine RBC that had been prepared by pre-treatment with a cholesterol depletion agent (methyl-beta-cyclodextrin, MCD) showed that the culture with 5 mM MCD-treated RBC inhibited the growth of B. bovis significantly as compared with that with the control RBC. In further experiments, the treatment with 5 mM MCD was proved to suppress both activities of the parasite, erythrocyte invasion and replication within the infected RBC. In contrast, a slight reduction in the membrane cholesterol by 1 mM MCD treatment promoted both their growth and erythrocyte invasion activity. These results indicate that erythrocyte invasion and replication by B. bovis are affected by the amount of cholesterol in the host erythrocyte membrane.