Functionality of Toxoplasma gondii antibodies in a population of Beninese pregnant women exposed to malaria.

Plasmodium falciparum and Toxoplasma gondii are two apicomplexan parasites that can lead to severe complications for the newborn when contracted during pregnancy. This study explores the cross-reactivity of antibodies specific to both pathogens in pregnant women, exposed or not to malaria. The antibody response against full-length recombinant antigens from P. falciparum (PfAMA1, Pfs48/45) and T. gondii (TgAMA1, TgSAG1, TgGRA7), selected for their strong immunogenicity, was analysed on 150 plasma samples from women residing in Benin or France. The antibody functionality was assessed using P. falciparum in vitro Growth Inhibition Assay (GIA). As the main results, toxoplasmosis seropositive women with an ongoing P. falciparum infection better inhibited P. falciparum invasion compared to toxoplasmosis seronegative women (34.6% vs. 17.2%, p ≤ 0.01). Women with positive serologies for both parasites presented a significantly higher inhibition of P. falciparum invasion compared to those only seropositive for malaria (coef = 6.27, p = 0.076) in reference with double-negative women (coef = 11.35, p = 0.001). These data suggest that plasma samples containing anti-T. gondii IgG may contribute reducing the development of P. falciparum parasites. This study provides insight into the immune dynamics of the co-infection by these two apicomplexans with potential implications for developing cross-protective vaccines and therapies.