To evaluate the inhibitory effects of drugs on the growth of Babesia gibsoni,
relative quantification real-time PCR method was developed in this study. The 18S rRNA gene
was used as a target gene for the 2–ΔΔCt method analysis. Additionally, chicken RNA was
added to the parasitized blood before total RNA extraction. The chicken β-actin gene was
selected as an internal control gene for the 2–ΔΔCt method analysis. The 100 µL parasitized
blood samples with different percentages of parasitized erythrocytes (PPEs) (3%, 1.5%, 0.75%,
0.375% and 0.1875%) were prepared for relative quantification of B. gibsoni. Regression
analysis results revealed significant linear relationships between the relative quantification
value and parasitemia. 18S rRNA gene expression was significantly decreased after treatment
with diminazene aceturate and artesunate in vitro drug sensitivity test. This result suggested
that this relative quantification real-time PCR method can be used to evaluate the effects of
drug inhibition.