PhD Student Looking for New Toxoplasmosis Treatment Methods

Toxoplasmosis is a disease caused by the protozoan Toxoplasma gondii (T. gondii). This parasite has the ability to infect many warm-blooded animals. It enters the human body with raw or undercooked meat, insufficiently cleaned vegetables, and when we drink contaminated water. Animals kept in the open are infected by ingestion of contaminated water or plants.

We become infected with the protozoan once and it accompanies us for the rest of our lives, often in a latent and inactive phase. 25 to 30 percent of the population can be infected. Toxoplasmosis does not give characteristic symptoms, and most of the infected remain unaware. The protozoan begins to multiply only when immunity decreases. It is dangerous for children and the elderly, for transplant recipients, as well as the developing foetus and pregnant women. T. gondii invasion can lead to brain damage and even death in immunocompromised individuals.

Adrian Bekier from the Department of Immunology and Infectious Biology at the University of Lodz undertakes research into the treatment of toxoplasmosis. The doctoral student explains that so far no effective method has been developed that would allow to completely eliminate the parasite from the infected organism.

Many drugs used to treat toxoplasmosis inhibit the important metabolic pathway of folic acid. However, these drugs only reduce the level of tissue damage. The scientist explains that when the intracellular parasite begins to intensively multiply, it destroys and attacks neighbouring cells. Therapy can only limit the extent of damage, but is burdened with side effects.

"Currently used therapies cause a number of side effects, such as allergic reactions, low count of white blood cells, anaemia, a decrease in platelets, arrhythmias, gastrointestinal disorders and skin discoloration. Therefore, the search for less toxic and more selective drugs continues," the research project leader says.

What`s more, the protozoan becomes resistant to commonly used drugs. Therefore, in cooperation with the Department of Organic Chemistry of the Faculty of Pharmacy and the Department of Medical Analytics, Medical University of Lublin, new derivatives of the compound with ability to inhibit the growth of T. gondii proven in preliminary experiments and with low toxicity for host cells have been synthesized. The doctoral student hopes that on this basis it will be possible to develop a new drug for toxoplasmosis.

"We can identify various infectious stages in the life cycle of T. gondii. The main source of human infection is eating raw or undercooked meat containing tissue cysts filled with bradyzoites, or vegetables contaminated with soil containing oocysts with sporozoites, or drinking water contaminated with the protozoan. In addition, the parasite can be transmitted through transfusion blood, including transplantation of organs, or from mother to foetus through the placenta," Bekier says.

He explains that the acute phase of toxoplasmosis begins when the parasite is released from tissue cysts and oocysts to transform into so-called tachyzoites. Under the pressure of the host`s developed immune response, tachyzoites transform into slowly dividing bradyzoites enclosed into cysts. This is the beginning of the chronic phase. Cysts can embed themselves in various tissues, for example nerve or muscle tissue, and stay in dormant form for the rest of our lives.

The only known definitive host of T. gondii are cats. They become infected mainly through predation on indirect hosts infected with the parasite, and then excrete infectious forms of the protozoan for a certain period. Bekier emphasizes that currently the only effective method of preventing T. gondii infection is health prevention, especially raising awareness of future mothers and early diagnosis of pregnant women and newborns.

The National Science Centre awarded nearly 140 thousand PLN from the PRELUDIUM competition funds for the project "Antiparasitic properties and identification of molecular targets of new thiosemicarbazide and thiazolidinone derivatives in invasions of the Toxoplasma gondii etiology". The doctoral project supervisor is Dr. Katarzyna Dzitko from the University of Lodz.

PAP - Science in Poland, Karolina Duszczyk

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