Figure 2. Percentage of tick cells with attached or internalized spirochetes as determined by flow cytometry. The tick cell lines AVL/CTVM17 (AVL17), BME/CTVM2 (BME2), HAE/CTVM8 (HAE8), IDE8, IRE/CTVM19 (IRE19), ISE6, RA243 and RAE/CTVM1 (RAE1) were inoculated with Borrelia burgdorferi, stained with PKH67, and cultivated in two different concentrations of medium, namely 10% BSK-H medium + 90% tick cell medium and 90% BSK-H medium + 10% tick cell medium. Data are reported as mean ± SD. There were no significant differences (*P>0.05) for the IRE19, ISE6 and RAE1 cell lines between the two combinations of culture media (ANOVA).