Background: Toxoplasmosis is a zoonotic disease caused by the intracellular opportunistic protozoan,
T. gondii that infects both vertebrate and invertebrate cells. Nanoparticles (NPs) provide promising
therapeutic agents for effective treatment of parasitic diseases, by overcoming the drawbacks of low
bioavailability and poor cellular permeability of anti-parasitic drugs.
Objective: To assess the therapeutic effect of gold (Au) NPs on experimentally infected mice with chronic
toxoplasmosis.
Material and Methods: Sixty-five laboratory-bred female Swiss albino mice were included. Five mice
were left as control negative (non-infected non-treated), while the rest were experimentally infected
orally with avirulent T. gondii strain (ME49). Fifty days post infection (pi), infected mice were divided
into 4 groups (15 mice each); group 1: control group (infected non-treated); group 2: treated with
Spiramycin (Rovamycin); group 3: treated with low-dose AuNPs; and group 4: treated with high-dose
AuNPs. Treatment was administered orally for 10 days. All mice were sacrificed sixty days pi. Assessment
of the therapeutic effect of AuNPs was achieved using parasitological, histopathological and biochemical
parameters. The first included estimation of the parasite tissue cysts numbers and size in impression
smears from brain, liver and spleen; histopathological parameters evaluated inflammation, necrosis and
hemorrhages in tissues. Liver transaminases: aspartate transaminase (AST) and alanine transaminase
(ALT) were measured in sera of all groups as a biochemical parameter.
Results: Statistically significant reductions were observed in the mean cyst count and size in brain, liver,
and spleen of the infected treated group with high dose AuNPs (group 4) compared to the other infected
groups. Histopathological examination of the brain, liver and spleen tissues showed that inflammatory
reaction was decreased in both AuNPs-treated groups in comparison to Spiramycin-treated group and the
non-treated mice. There was a significant reduction in the mean values of ALT and AST in mice treated
with AuNPs high dose in comparison to other groups (P<0.05).
Conclusion: AuNPs have a potentially therapeutic effect especially the high dose against experimental
chronic toxoplasmosis.