Toxoplasma gondii is a protozoan parasite infecting nearly one third of the global population. Severe immunosuppression in chronically infected individuals results in reactivated toxoplasmosis (RT), a devastating complication following hematopoietic stem cell transplantation (HSCT), particularly in allogeneic (allo-) recipients. Despite the staggering annual rise in the number of HSCT across Europe, there are still no standardized guidelines on the monitoring and treatment of RT. Moreover, limited treatment options for RT are inadequate for HSCT patients due to side myelotoxicity and ineffective since they act only on circulating parasites. Our project entitled "Reinvention of the diagnostic algorithm and treatment options for reactivated toxoplasmosis" (acronym ToxoReTREAT) funded for the next 3 years by the Science Fund of the Republic of Serbia (as of December 1st, 2023), is using multidisciplinary approach to tackle this challenge.

The aim of ToxoReTREAT is to resolve the problem of RT in allo-HSCT recipients combining medicine, pharmacy and computer science to provide efficient novel treatment options and cost-benefit improvements in the management of RT. The results of molecular monitoring of RT (18 allo-HSCT recipients already recruited), T. gondii isolation and characterization, identification of host-related and treatment-related risk factors, will lead to improved diagnostic algorithm and eventually the up-to-date National guidelines. Acridine and acridone derivatives, newly synthetized and modified throughout this project (20 acridines already synthetized), will be tested in both in vitro and in vivo experimental models of RT, using T. gondii strains isolated from allo-HSCT recipients. ToxoReTREAT will provide at least one drug candidate for RT with reduced toxicity and increased overall efficacy on T. gondii tachyzoites and bradyzoites, in comparison to standard treatment. This research should instigate an increased interest of the pharmaceutical industry to engage in development of better new drugs for the treatment of toxoplasmosis. Application of a freely available ImageJ software to advance automated image scoring for chemotherapy results (we"ve obtained 15 high-resolution images of in vitro experimental results so far), both straightforward and cost-effective mathematically quantifiable approach, will contribute to more feasible transfer of knowledge gained through chemotherapy experiments.