Clofazimine Inhibits the Growth of Babesia and Theileria Parasites In Vitro and In Vivo

Abstract

The present study evaluated the growth-inhibitory effects of clofazimine, currently used for treating leprosy, against Babesia bovis, B. bigemina, B. caballi, and Theileria equi in in vitro culture and against Babesia microti in mice. The 50% inhibitory concentrations (IC 50 s) of clofazimine against the in vitro growth of B. bovis, B. bigemina, B. caballi, and T. equi were 4.5, 3, 4.3, and 0.29 M, respectively. In mice infected with B. microti, treatment with 20 mg/kg of body weight of clofazimine administered orally resulted in a significantly lower peak parasitemia (5.3%) than that in the control group (45.9%), which was comparable to the subcutaneous administration of 25 mg/kg diminazene aceturate, the most widely used treatment for animal piroplasmosis. Although slight anemia was observed in both clofazimine-and diminazene aceturate-treated infected mice, the level and duration of anemia were lower and shorter, respectively, than those in untreated infected mice. Using blood transfusions and PCR, we also examined whether clofazimine completely killed B. microti. On day 40 postinfection, when blood analysis was performed, parasites were not found in blood smears; however, the DNA of B. microti was detected in the blood of clofaziminetreated animals and in several tissues of clofazimine-and diminazene aceturate-treated mice by PCR. The growth of parasites was observed in mice after blood transfusions from clofazimine-treated mice. In conclusion, clofazimine showed excellent inhibitory effects against Babesia and Theileria in vitro and in vivo, and further study on clofazimine is required for the future development of a novel chemotherapy with high efficacy and safety against animal piroplasmosis and, possibly, human babesiosis.

Chemotherapeutic efficacies of a clofazimine and diminazene aceturate combination against piroplasm parasites and their AT-rich DNA-binding activity on Babesia bovis

“…In agreement with the previous study 6 , the effect of 20 mg/kg CF was comparable to and sometimes higher than that of 25 mg/kg DA. Therefore 25 mg/kg, the highest dosage, was considered as a baseline for selection of dosages in combination therapies in mice experiment.…”

“…The in vivo inhibition assay was performed as previously described 6 . Briefly, mice (5/group) were injected intraperitoneally with 1 × 10 7 B. microti –infected RBCs.…”

“…We recently reported that clofazimine (CF) has a potent inhibitory effect on the growth of piroplasms, but CF could not completely eliminate B . microti in mice 6 . CF is an antibiotic used in combination chemotherapies against leprosy 7 .…”

Performance and consistency of a fluorescence-based high-throughput screening assay for use in Babesia drug screening in mice

“…Moreover, the combined therapy exhibited rapid recovery of HCT levels as compared with those recently observed with clofazimine, which causes significantly lower hematocrit values on days 8 and 12 p.i. than those of the control 22 . Although the PYR/DA combination exhibited potential antibabesial effect against B. microti in the blood collected from treated mice using fluorescence assay, parasite’s DNA was detected in the mice organs by nested PCR 30- days post-treatment.…”

“…Female BALB/c mice aged 8 weeks were purchased from CLEA Japan (Tokyo, Japan) for use in this study and kept under specific pathogen-free conditions. The Munich strain of B. microti was maintained by passage in the blood of BALB/c mice 22 .…”