In vitro efficacy of bumped kinase inhibitors against Besnoitia besnoiti tachyzoites

Jiménez-Meléndez, Alejandro; Ojo, Kayode K.; Wallace, Alexandra M.; Smith, Tess R.; Hemphill, Andrew; Balmer, Vreni; Regidor‐Cerrillo, Javier; Ortega‐Mora, Luis Miguel; Hehl, Adrian B.; Fan, Erkang; Maly, Dustin J.; Voorhis, Wesley C. Van; Álvarez‐García, Gema

doi:10.1016/j.ijpara.2017.08.005

Cited by 26 publications

(20 citation statements)

References 39 publications

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“…Thus, repurposing of compounds that are already licensed or under development is a faster way to identify novel candidate therapeutics against B. besnoiti infection. This has been demonstrated in studies on thiazolides (9), cationic arylimidamides (10), bumped kinase inhibitors (BKIs), diclazuril and decoquinate (11,12), and buparvaquone (13).…”

Section: Introductionmentioning

confidence: 86%

Activities of Endochin-Like Quinolones Against in vitro Cultured Besnoitia besnoiti Tachyzoites

et al. 2020

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Endochin-like quinolones (ELQs) potently inhibit the proliferation of Plasmodium, Toxoplasma, Neospora, and Babesia by targeting the cytochrome b Qo and Qi sites and interfering with oxidative phosphorylation and pyrimidine biosynthesis. The activities of 14 different ELQs were assessed against B. besnoiti tachyzoites grown in human foreskin fibroblasts (HFF) by quantitative real time PCR. The values for 50% proliferation inhibition (IC50) of five ELQs were determined in a 3-days growth assay after an initial screen of 12 ELQs at 0.01, 0.1, and 1 µM. The IC50s of ELQ-121,-136, and-316 were 0.49, 2.36, and 7.97 nM, respectively. The IC50s of ELQs tested against B. besnoiti were higher than IC50s previously observed for P. falciparum and T. gondii. However, the B. besnoiti cytochrome b sequence and the predicted Qo and Qi ELQ binding sites in the Toxoplasma, Neospora, and Besnoitia cytochrome b are virtually identical, suggesting that the differences in ELQ susceptibility are not due to variations in the substrate binding sites. TEM of ELQ-treated parasites primarily demonstrated alterations within the parasite mitochondrion, profound thickening of the nuclear membrane, as well as increased vacuolization within the tachyzoite cytoplasm. Long-term treatment assays of intracellular B. besnoiti with ELQs for up to 20 days followed by the release of drug pressure caused a substantial delay in parasite growth and proliferation while ELQs were present, but parasite proliferation resumed days after ELQs were removed. Interestingly, structural alterations persisted after ELQ removal and parasite proliferation was slowed. These findings provide a basis for further in vivo studies of ELQs as therapeutic options against B. besnoiti infection.

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Section: Introductionmentioning

confidence: 86%

Activities of Endochin-Like Quinolones Against in vitro Cultured Besnoitia besnoiti Tachyzoites

et al. 2020

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“…The high degree of efficacy and specificity of BKIs in apicomplexans relative to mammalian kinases is due to differences in the topology of a hydrophobic pocket within the ATP binding site that is, in part, determined by the size of their respective gatekeeper residues [9]. BKIs have proven in vitro activity against Babesia bovis [6] and Besnoitia besnoiti [10], as well as in vitro and in vivo against Cryptosporidium spp. [11–17], Cystoisospora suis [18], T. gondii [19–21] and N. caninum [21–23].…”

Section: Introductionmentioning

confidence: 99%

Comparative assessment of the effects of bumped kinase inhibitors on early zebrafish embryo development and pregnancy in mice

Anghel

Winzer

Imhof

et al. 2020

Preprint

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Bumped kinase inhibitors (BKIs) are effective against a variety of apicomplexan parasites. Fifteen BKIs with promising in vitro efficacy against Neospora caninum tachyzoites, low cytotoxicity in mammalian cells, and no toxic effects in non-pregnant BALB/c mice, were assessed in pregnant mice. Drugs were emulsified in corn oil and applied by gavage for 5 days. Five BKIs did not affect pregnancy, 5 BKIs exhibited 15-35% of neonatal mortality, and 5 compounds caused strong effects (infertility, abortion, stillbirth and pup mortality). Additionally, the impact of these compounds on zebrafish (Danio rerio) embryo development was assessed by exposing freshly fertilized eggs to 0.2-50μM of BKIs and microscopical monitoring of embryo development in a blinded manner during 4 days. We propose an algorithm that includes quantification of malformations and embryo deaths, and established a scoring system that allows to calculate an impact score (Si) that indicates at which concentrations BKIs visibly affect zebrafish embryo development. Comparison of the two models showed that for 9 compounds no clear correlation between Si and pregnancy outcome was visible. However, those 3 BKIs affecting zebrafish embryos only at high concentrations (40μM or higher) did not impair mouse pregnancy at all, and those 3 compounds that inhibited zebrafish embryo development already at 0.2μM showed detrimental effects in the pregnancy model. Thus, the zebrafish embryo development test has a limited predictive value to foresee pregnancy outcome in BKI-treated mice. We conclude, that maternal health-related factors such as cardiovascular, pharmacokinetic and/or bioavailability properties also contribute to BKI-pregnancy effects.

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“…The control and prevention of this disease relies only on diagnostic and management measures, as no chemotherapeutics are available and no vaccines are licensed in Europe (Álvarez‐García, Frey, Mora, & Schares, ). Promising drugs have been tested in vitro (Cortes, Muller, Boykin, Stephens, & Hemphill, ; Jiménez‐Meléndez et al., ). However, an appropriate ruminant experimental model has not been developed yet; this model is a requirement to test the safety and efficacy of these potential prophylactic and therapeutic tools.…”

Section: Introductionmentioning

confidence: 99%

Effect of parasite dose and host age on the infection with Besnoitia besnoiti tachyzoites in cattle

Diezma-Díaz

Jiménez-Meléndez

et al. 2018

Transbound Emerg Dis

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Bovine besnoitiosis is continuing to spread in Europe. Therefore, the development of ruminant animal models of infection is urgently needed to evaluate therapeutic and prophylactic tools. Herein, we studied the effect of parasite dose and host age on the infection dynamics with Besnoitia besnoiti tachyzoites in cattle in two independent experimental infections. In experiment A, twelve 3-month-old male calves were inoculated intravenously with either three different doses of tachyzoites (G1: 10 ; G2: 10 ; G3: 10 ) or with PBS (G4). In experiment B, six 14-month-old bulls were inoculated with 10 tachyzoites based on results obtained in experiment A. In both trials, clinical signs compatible with acute and chronic besnoitiosis were monitored daily; blood and skin samples were collected regularly for 70-115 days post-infection (pi). Finally, animals were killed, and tissues were collected for lesion and parasite detections. Infected animals developed mild-moderate signs compatible with acute besnoitiosis. Lymphadenopathy and fever were observed in both calves (from 12 hr until 7 days pi) and bulls (from 6 days until 9 days pi). Seroconversion was detected at 16-19 days pi, and antibody levels remained high. Infected animals did not developed characteristic clinical signs and macroscopic lesions of chronic besnoitiosis. However, successfully, parasite-DNA was detected in a reduced number of target tissues: conjunctiva, ocular sclera, epididymis, skin of the scrotum and carpus in calves (n = 10, 6 of which belonged to G3), and pampiniform plexus and testicular parenchyma in bulls. Remarkably, one tissue cyst and mild microscopic lesions were also detected. In summary, inoculated animals developed the acute besnoitiosis and chronic infection was evidenced by microscopic findings. However, our results suggest that tachyzoite dose and host age are not key variables for inducing clinical signs and macroscopic lesions characteristic of chronic besnoitiosis. Thus, a further refinement of this model should evaluate other parasite- and host-dependent variables.

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In vitro efficacy of bumped kinase inhibitors against Besnoitia besnoiti tachyzoites

Cited by 26 publications

References 39 publications

Activities of Endochin-Like Quinolones Against in vitro Cultured Besnoitia besnoiti Tachyzoites

Activities of Endochin-Like Quinolones Against in vitro Cultured Besnoitia besnoiti Tachyzoites

Comparative assessment of the effects of bumped kinase inhibitors on early zebrafish embryo development and pregnancy in mice

Effect of parasite dose and host age on the infection with Besnoitia besnoiti tachyzoites in cattle

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