• Genomics & Informatics
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• 제14권2호
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• pp.53-61
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• 2016

Toxoplasma gondii is an intracellular Apicomplexan parasite and a causative agent of toxoplasmosis in human. It causes encephalitis, uveitis, chorioretinitis, and congenital infection. T. gondii invades the host cell by forming a moving junction (MJ) complex. This complex formation is initiated by intermolecular interactions between the two secretory parasitic proteins-namely, apical membrane antigen 1 (AMA1) and rhoptry neck protein 2 (RON2) and is critically essential for the host invasion process. By this study, we propose two potential leads, NSC95522 and NSC179676 that can efficiently target the AMA1 hydrophobic cleft, which is a hotspot for targeting MJ complex formation. The proposed leads are the result of an exhaustive conformational search-based virtual screen with multilevel precision scoring of the docking affinities. These two compounds surpassed all the precision levels of docking and also the stringent post docking and cumulative molecular dynamics evaluations. Moreover, the backbone flexibility of hotspot residues in the hydrophobic cleft, which has been previously reported to be essential for accommodative binding of RON2 to AMA1, was also highly perturbed by these compounds. Furthermore, binding free energy calculations of these two compounds also revealed a significant affinity to AMA1. Machine learning approaches also predicted these two compounds to possess more relevant activities. Hence, these two leads, NSC95522 and NSC179676, may prove to be potential inhibitors targeting AMA1-RON2 complex formation towards combating toxoplasmosis.

• Parasites, Hosts and Diseases
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• 제51권5호
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• pp.503-510
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• 2013

Toxoplasma gondii is an apicomplexan parasite with a broad host range of most warm-blooded mammals including humans, of which one-thirds of the human population has been infected worldwide which can cause congenital defects, abortion, and neonatal complications. Here, we developed a rapid diagnostic test (RDT) for T. gondii infection. Antigenic N-terminal half of the major surface antigen (SAG1) was linked with intrinsically unstructured domain (IUD) of dense granule protein 2 (GRA2). The recombinant GST-GRA2-SAG1A protein was successfully expressed and purified as 51 kDa of molecular weight. Furthermore, antigenicity and solubility of the rGST-GRA2-SAG1A protein were significantly increased. The overall specificity and sensitivity of GST-GRA2-SAG1A loaded RDT (TgRDT) were estimated as 100% and 97.1% by comparing with ELISA result which uses T. gondii whole cell lysates as the antigen. The TgRDT tested with Uganda people sera for field trial and showed 31.9% of seroprevalence against T. gondii antibody. The TgRDT is proved to be a kit for rapid and easy to use with high accuracy, which would be a suitable serodiagnostic tool for toxoplasmosis.

• 동의생리병리학회지
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• 제22권1호
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• pp.96-99
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• 2008

Toxoplasma gondiiis a widespread apicomplexan parasite which is able to infect virtually all warm-blooded vertebrates. Twenty-two percent of the U.S. population is infected, but severe disease in adults is mainly limited to immunosuppressed patients. In patients with acquired immunodeficiency syndrome(AIDS), T. gondii causes a life-threatening opportunistic infection, with Toxoplasma encephalitis as its most severe manifestations. T. gondii is also known to cause congenital infection and is among the pathogens with the highest incidence of complications in pregnancies. Despite its clinical importance, only very few therapeutic drugs against T. gondii are available, all of which target the rapidly dividing tachyzoites, leaving the dormant encysted bradyzoite stage unaffected. We searched 15 traditional medicines that have anti-inflammatory effect from dongyibogam and Traditional Chinese medicine. In vitro studies were performed with HeLa cell cultures, with quantification of Toxoplasma growth by a cell proliferation assay. The result of experiment shows the selectivity of Citrus unshiu Markovich is 6.0. This is higher than sulfadiazine (selectivity was 1.63). For in vivo studies, mice were acutely infected intraperitoneally with $10^5$ tachyzoites of the virulent RH strain and then treated per orally for 4 days from 6 hours postinfection. Efficacy was assessed by sequential determination of parasite burdens in peritoneal cavity. In vivo, Citrus unshiu Markoviche inhibited Toxoplasma growth at a concentration of 10㎎/㎏ of body weight per day, the inhibition ratio was estimated to be 64.01%.