BthTX-II, an Asp49 PLA from , Impairs Infection: In Vitro and Ex Vivo Approaches.

: , an obligate intracellular parasite, poses a major global health concern owing to its potential for congenital transmission, particularly during pregnancy. Current pharmacological treatments, including spiramycin and pyrimethamine, exhibit limitations in both efficacy and safety, underscoring the need for novel therapeutic strategies. In this study, we investigated the antiparasitic potential of BthTX-II, an Asp49 phospholipase A (PLA) isolated from venom, in human trophoblast cells (BeWo) and third-trimester human placental explants infected with . : In vitro assays were performed using BeWo cells infected with tachyzoites and treated with non-cytotoxic concentrations of BthTX-II (3.125, 1.56, and 0.78 µg/mL). An ex vivo model employing third-trimester human placental villous explants was used under similar conditions. Parasite proliferation, adhesion, and invasion were assessed alongside host immune response modulation. : Our findings demonstrate that BthTX-II reduces proliferation in BeWo cells at all tested non-cytotoxic concentrations. The toxin also significantly impaired parasite adhesion and invasion while modulating host immune response by upregulating interleukin (IL)-6, IL-8, and macrophage migration inhibitory factor (MIF), and downregulating vascular endothelial growth factor-potentially disrupting parasite proliferation. In placental villous explants, BthTX-II (1.56 μg/mL) reduced proliferation and modulated IL-8, MIF, and tumour necrosis factor-alpha levels without compromising tissue viability. : These findings highlight BthTX-II as a potential candidate in toxoplasmosis treatment. Further investigation should focus on its dual role in limiting parasite development and modulating immune responses at the maternal-fetal interface.