The research focus of the Ojo Lab is to develop novel, robust, safe and affordable antimicrobial agents that can withstand the threat of resistance while effectively treating debilitating parasitic diseases.
Studies have shown that physiologically important enzymes necessary for parasite survival and maintenance could be potential anti-parasitic drug targets. It has been demonstrated that inhibition of the calcium-dependent protein kinases (CDPKs) of some members of Phylum Apicomplexa prevents invasion of host cells and stops parasite replication.
This has been key in our ongoing studies, as apicomplexan parasites’ CDPKs have a unique hydrophobic pocket within the ATP-binding site that allows for the development of inhibitors that selectively target apicomplexan CDPKs with negligible to no effect on human kinases. Our research may facilitate the development of safe and effective broad spectrum therapeutic agents that will treat debilitating parasitic diseases such as cryptosporidiosis, toxoplasmosis, neosporidiosis, besnoitiosis and prevent equine protozoal myeloencephalitis.
The Ojo Lab is utilizing the experience and tools developed from their studies on Toxoplasma gondii, Neospora caninum and Cryptosporidium parvum to design a new class of malaria transmission-blocking compounds. There are many effective therapeutics to treat malaria infection in humans, however, the Plasmodium parasite remains transmissible to mosquitoes for a period of time after the symptoms of infection have ceased in the human. This allows for reinfection of the mosquito carrier that would augment the spread of infection in humans.
Our compounds act via inhibition of PfCDPK4, which efficiently blocks Plasmodium parasite infection of mosquitoes. Our studies indicate that this strategy could lead to non-toxic, selective inhibitors with favorable oral pharmacokinetic properties that block malaria transmission to mosquitoes, making them excellent leads for further drug development. Since the CDPK4 genes of all Plasmodium species with known genomes are highly conserved, an effective lead compound will likely be useful in blocking the transmission of all 5 species known to cause human malaria, which has a significant public health implication and potential benefit.
We are currently using a similar, unique target-based approach for the development of specific inhibitors of Giardia lamblia as an alternative treatment option for giardiasis diarrhea. The Paredez and Ojo Labs have engineered strains of G. lamblia with luciferase-based reporter systems for efficient and accurate drug evaluation both in vitro and in vivo. The bioluminescent reporter was the keystone for developing a phenotypic high throughput screening cell assay and a reliable mouse model of infection to facilitate the search for efficacious compounds.
Our HTS cell assay using one of these strains has been adapted for 384-well plates to accommodate vast numbers of compounds. The mouse infection model is designed for live, whole animal imaging as a non-invasive method of monitoring infection and treatment efficacy, made possible by the luciferase reporter present in the Giardia strain.
Current efforts are focused toward developing a dual efficacy drug against Giardia and Cryptosporidium, since they occupy similar anatomical locations. Various compound libraries are being screened against both parasites and promising leads will move into animal studies for further development to produce preclinical drug candidates.