Treatment with Bumped Kinase Inhibitor 1294 Is Safe and Leads to Significant Protection against Abortion and Vertical Transmission in Sheep Experimentally Infected with Toxoplasma gondii during Pregnancy

16 páginas, 3 tablas, 6 figuras.Previous studies on drug efficacy showed low protection against abortion and vertical transmission of Toxoplasma gondii in pregnant sheep. Bumped kinase inhibitors (BKIs), which are ATP-competitive inhibitors of calcium-dependent protein kinase 1 (CDPK1), were shown to be highly efficacious against several apicomplexan parasites in vitro and in laboratory animal models. Here, we present the safety and efficacy of BKI-1294 treatment (dosed orally at 100 mg/kg of body weight 5 times every 48 h) initiated 48 h after oral infection of sheep at midpregnancy with 1,000 TgShSp1 oocysts. BKI-1294 demonstrated systemic exposure in pregnant ewes, with maximum plasma concentrations of 2 to 3 M and trough concentrations of 0.4 M at 48 h after each dose. Oral administration of BKI-1294 in uninfected sheep at midpregnancy was deemed safe, since there were no changes in behavior, fecal consistency, rectal temperatures, hematological and biochemical parameters, or fetal mortality/morbidity. In ewes infected with a T. gondii oocyst dose lethal for fetuses, BKI-1294 treatment led to a minor rectal temperature increase after infection and a decrease in fetal/lamb mortality of 71%. None of the lambs born alive in the treated group exhibited congenital encephalitis lesions, and vertical transmission was prevented in 53% of them. BKI-1294 treatment during infection led to strong interferon gamma production after cell stimulation in vitro and a low humoral immune response to soluble tachyzoite antigens but high levels of anti-SAG1 antibodies. The results demonstrate a proof of concept for the therapeutic use of BKI-1294 to protect ovine fetuses from T. gondii infection during pregnancy.We gratefully acknowledge the SALUVET group (Complutense University of Madrid, Spain), Luis Miguel Ferrer, Jose Ventura, José Calasanz Jiménez, Francisco Saura, Teresa Navarro, and José María González from the University of Zaragoza (Spain), and Victor Herrero and Javier Blanco from Clinical Veterinary Hospital (Complutense University of Madrid, Spain) for their excellent technical assistance, Dale Kempf and Kennan Marsh, from AbbVie, Inc., for their suggestion of the Phosal vehicle used in the experiments reported here, Rama S. R. Vidadala and Dustin J. Maly, Department of Chemistry, University of Washington, for characterization and further purification of BKI-1294, and advice from Robert Choy and Eugenio L. de Hostos from the PATH Drug Development Program. The Animal Experimentation Service (SEA) at the University of Zaragoza is acknowledged for providing their facilities to carry out the reproduction program. R.S.-S. is supported by a fellowship from the Spanish Ministry of Education, Culture and Sports (MECD), as a part of the Program of Training of University Teaching Staff (FPU; grant number FPU13/03438). A.H. is supported by a Swiss National Science Foundation grant (no. 310030-165782). This work was supported by the Public Health Service, National Institutes of Health, Bethesda, MD (grants R01 AI 111341 and R01 HD 080670), the U.S. Department of Agriculture (grant 2014-67015-22106), and the Community of Madrid, Spain (PLATESA2, P2018/BAA-4370). I.F., A.H., K.K.O., W.C.V.V., and L.M.O.-M. conceived the study and participated in its design. R.S.-S. wrote the manuscript, with results interpretation and discussion inputs from I.F., J.R.-C., A.H., M.A.H., L.K.B., W.C.V.V., and L.M.O.-M. J.J.R. selected the animals and executed the reproductive program. R.S.-S., I.F., and M.R. carried out oocyst infection and drug administration. R.S.-S., I.F., M.R., M.P.D., M.G.-H., E.T., and J.B. participated in clinical examination and sampling of animals and performed necropsies and hematological, biochemical, and histopathological analyses. M.H., L.K.B., R.C., G.R.W., and K.K.O. determined the pharmacokinetics of the compound. R.S.-S. performed peripheral blood stimulation assay, serological assays, PCR analyses, statistical analysis, and interpretation of the results. All authors read and approved the final manuscript. W.C.V.V. is the president and co-owner of ParaTheraTech, Inc., a company that is developing BKIs for animal health. W.C.V.V. did not perform the experiments or interpret the results of the experiments, but he did edit the paper and helped plan the experiments. The other authors have no competing interests to declare