Vertical transmission of Toxoplasma gondii during late gestation: Efficacy of spiramycin-nanoparticles and Aluvia (lopinavir/ritonavir) in offspring of infected mice.

Congenital toxoplasmosis, resulting from vertical transmission of Toxoplasma gondii during pregnancy, poses serious risks to the fetus. This study investigated the efficacy and therapeutic potential of spiramycin, spiramycin-loaded chitosan nanoparticles and Aluvia (a combination of lopinavir and ritonavir) in mitigating fetal infection during late gestation in Swiss albino mice. Forty pregnant mice were included in the study and divided into control and experimental groups (10 and 30 respectively). Each pregnant mouse was injected subcutaneously with 30 tachyzoites of the virulent T. gondii RH strain during the 3rd gestation period (on day 15 of pregnancy). Therapeutic efficacy was assessed by evaluating parasite load, in offspring's liver, spleen, and brain impression smear. Quantitative real-time PCR targeted B1 gene was used to detect the parasite load in the offspring's liver. Spiramycin-loaded CNPs revealed a significant decrease in parasite load in all the studied organs compared to spiramycin and Aluvia. Alongside spiramycin-loaded CNPs, Aluvia revealed a high parasite reduction rate in brain impression smear. Real-time PCR confirmed that spiramycin-loaded CNPs achieved the highest and most remarkable reduction rate (81%) in parasite count in the liver of offspring. In conclusion, spiramycin-loaded CNPs and Aluvia showed promising results, particularly in significantly reducing parasite burden in the offspring's brain, indicating their potential ability to cross the placenta and the fetal blood brain-barrier (BBB). These findings provide useful data on the transmission of Toxoplasma to offspring organs and highlight the promise of spiramycin nanoparticle formulation and Aluvia in improving therapeutic outcomes for congenital toxoplasmosis and minimizing the severity of fetal infection.