NON-ESSENTIAL AND ESSENTIAL METAL EFFECTS ON INTRACELLULAR TOXOPLASMA GONDII
Laís Pessanha de Carvalho* and Edésio José Tenório de Melo
ABSTRACT
Toxoplasma gondii is an obligatory protozoan parasite that uses sophisticated mechanisms to guarantee its
survival at the intracellular environment of all eukaryotic host cells. However, metals are very important for
survival and development of several parasites at host intracellular environment. The parasites use essential metals
as co-factors or structural components of metalloproteins. These proteins are involved in host cell invasion,
establishment on cytoplasm, vacuole formation, parasite multiplication and host cell egress. Nonetheless, the
understanding of toxicological and biochemical impact of metallic ions on biological systems of intracellular
replicative form of T. gondii - tachyzoite is poorly known. The aim of this study was utilize the relationship of
host cell - Toxoplasma gondii to verify the effects of non-essential (CdCl2 and HgCl2) and essential (ZnCl2)
metals on the maintenance of intracellular infection. We used different concentrations (1, 3, 5, 8, 10 and 20 μM)
and incubation times (2, 12 and 24 h) to observe the progressive toxic effect to parasite. Ultrastructural features
were analyzed under light and transmission electron microscopy. The results indicated that uninfected culture were
more susceptible to toxicity of non-essential metals than infected ones. However, the infection decreased during
the incubation with these metals while tachyzoites underwent elimination at low time and concentrations of the
non-essential metals. These results suggest that parasites were very susceptible to these metals. Therefore, the
essential metal (ZnCl2) protected the host cells and parasites against toxic effects of non-essential metals (HgCl2
and CdCl2).
Keywords: cadmium, infected cells, mercury, T. gondii and zinc.
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