A Novel Calcium-Dependent Protein Kinase 1 Inhibitor Potently Prevents Toxoplasma gondii Transmission to Foetuses in Mouse.

Treatments currently used to prevent congenital toxoplasmosis are non-specific of Toxoplasma gondii and have grievous side effects. To develop a more specific and less toxic drug, we have designed SP230, an imidazo[1,2-b]pyridazine salt targeting the Toxoplasma gondii calcium-dependent protein kinase 1 (TgCDPK1) and active against acute toxoplasmosis in mice. Efficiency of SP230 to inhibit foetal transmission of the parasite was evaluated in a mouse model of congenital toxoplasmosis. Swiss mice were infected at mid-pregnancy with tachyzoites or cysts of the ME49 strain of T. gondii by intraperitoneal and oral route, respectively, and treated with SP230 at 50 mg/kg for 5 days by the same routes. Parasite burden in organs of dams and in foetuses was measured by quantitative PCR. Intraperitoneal administration of SP230 drastically reduced the number of parasites (more than 97% of reduction) in the brain and lungs of dams, and led to a reduction of 66% of parasite burden in foetuses. Oral administration of SP230 was particularly efficient with 97% of reduction of parasite burdens in foetuses. SP230 did not impact number and weight of offspring in our conditions. This inhibitor of TgCDPK1 is a promising candidate for the development of alternative therapeutics to treat infected pregnant women.

Engineering and Functional Evaluation of Neutralizing Antibody Fragments Against Congenital Toxoplasmosis.

Maternal-fetal transmission of Toxoplasma gondii tachyzoites acquired during pregnancy has potentially dramatic consequences for the fetus. Current reference-standard treatments are not specific to the parasite and can induce severe side effects. In order to provide treatments with a higher specificity against toxoplasmosis, we developed antibody fragments-single-chain fragment variable (scFv) and scFv fused with mouse immunoglobulin G2a crystallizable fragment (scFv-Fc)-directed against the major surface protein SAG1. After validating their capacity to inhibit T. gondii proliferation in vitro, the antibody fragments' biological activity was assessed in vivo using a congenital toxoplasmosis mouse model. Dams were treated by systemic administration of antibody fragments and with prevention of maternal-fetal transmission being used as the parameter of efficacy. We observed that both antibody fragments prevented T. gondii dissemination and protected neonates, with the scFv-Fc format having better efficacy. These data provide a proof of concept for the use of antibody fragments as effective and specific treatment against congenital toxoplasmosis and provide promising leads.

[Tricks and misuses of rapid diagnostic testing for malaria diagnosis]. / Pièges et mésusages des tests de diagnostic rapide pour rechercher le paludisme en routine.

Molecular biology or immunochromatographic tests are conventionally offered as aids in the routine diagnosis of malaria. However, the interpretation of their results requires a precise knowledge of their limits, both by the biologist and the physician. It is in particular conditioned by thorough interview of the patient in order to seek a history of recent or even older malaria disease. We discuss herein the different usages and how to interpret such diagnostics, through a concrete example of a malaria case which was particularly tough to investigate.

Imidazo[1,2-b]pyridazines targeting Toxoplasma gondii calcium-dependent protein kinase 1 decrease the parasite burden in mice with acute toxoplasmosis.

The current therapeutic arsenal for toxoplasmosis is restricted to drugs non-specific to the parasite which cause important side effects. Development of more efficient and specific anti-Toxoplasma compounds is urgently needed. Imidazo[1,2-b]pyridazines designed to inhibit the calcium-dependent protein kinase 1 of Toxoplasma gondii (TgCDPK1) and effective against tachyzoite growth in vitro at submicromolar ranges were modified into hydrochloride salts to be administered in vivo in a mouse model of acute toxoplasmosis. All protonated imidazo[1,2-b]pyridazine salts (SP230, SP231 and SP232) maintained their activity on TgCDPK1 and T. gondii tachyzoites. Rat and mouse liver microsomes were used to predict half-life and intrinsic clearance, and the pharmacokinetic profile of the most rapidly degraded imidazo[1,2b]pyridazine salt (SP230) was determined in serum, brain and lungs of mice after a single administration of 50 mg/kg. Compounds were then tested in vivo in a murine model of acute toxoplasmosis. Mice infected with tachyzoites of the ME49 strain of T. gondii were treated for 4, 7 or 8 days with 25 or 50 mg/kg/day of SP230, SP231 or SP232. The parasite burdens were strongly diminished (>90% reduction under some conditions) in the spleen and the lungs of mice treated with imidazo[1,2-b]pyridazine salts compared with untreated mice, without the need for pre-treatment. Moreover, no increases in the levels of hepatic and renal toxicity markers were observed, demonstrating no significant signs of short-term toxicity. To conclude, imidazo[1,2-b]pyridazine salts have strong efficacy in vivo on acute toxoplasmosis and should be further tested in a model of mouse congenital toxoplasmosis.

Synthetic parasites: a successful mucosal nanoparticle vaccine against Toxoplasma congenital infection in mice.

AIM: Development of protein vaccine to prevent congenital infection is a major public health priority. Our goal is the design of mucosal synthetic pathogen inducing protective immune responses against congenital toxoplasmosis. MATERIALS & METHODS: Mice were immunized intranasally, establishing pregnancy and challenging orally. Placental immune response, congenital infection, pup growth, parasitic load rates were studied. RESULTS: Pups born to vaccinated infected dams had significantly fewer brain cysts, no intraocular inflammation and normal growth. Protection was associated with a placental cellular Th1 response downregulated by IL-6 and correlated with persistence of vaccine for few hours in the nose before being totally eliminated. CONCLUSION: Our vaccine conferred high protection against congenital toxoplasmosis. These results provide support for future studies of other congenital vaccine.

Pulmonary toxoplasmosis in immunocompromised patients with interstitial pneumonia: a single-centre prospective study assessing PCR-based diagnosis.

AIMS: Pulmonary toxoplasmosis has become a very rare parasitic infection since the advent of highly active antiretroviral therapies. It is generally diagnosed by the direct microscopic observation of Toxoplasma gondii tachyzoites in bronchoalveolar lavage fluid (BALF). The aim of this study was to assess possible improvements in diagnostic performance associated with the use of real-time PCR. METHODS: This prospective study was carried out on BALFs obtained from immunocompromised patients over a 2-year period. We systematically compared the results of conventional staining with those of molecular detection. RESULTS: Two cases of pulmonary toxoplasmosis were diagnosed for a total of 336 samples. PCR did not detect any additional cases and was more time-consuming than conventional staining. CONCLUSIONS: Conventional staining is a reliable technique and is probably the most appropriate method for experienced microbiology laboratories, whereas T. gondii-specific PCR may be useful for laboratories with less experience in parasitology. TRIAL REGISTRATION NUMBER: 2015_030, May 27th 2015.

[Toxoplasmic cyst and heart transplant: a case report of serological reactivation in an acute graft rejection context]. / Kyste toxoplasmique et transplant cardiaque : cas d'une réactivation sérologique dans un contexte de rejet de greffe.

We describe the case of a serological reactivation in a Toxoplasma-seropositive subject, following a cardiac transplantation transmitting cysts contained in the myocardial tissue. In a context of acute graft rejection, primary chemoprophylaxis enables to avoid onset of opportunistic toxoplasmosis, emerging with immunodepletion performed by high-dose steroids. Then, we draw up a brief review of the bibliographical literature about pathophysiological mechanisms of toxoplasmic reactivation in heart transplants.

Interleukin 17 receptor signaling is deleterious during Toxoplasma gondii infection in susceptible BL6 mice.

Th17 cells are involved in host defense against several pathogens. Using interleukin (IL) 17RA-deficient mice, we demonstrated reduced ileitis with diminished neutrophil recruitment and inflammatory lesions in the ileum, in the regional lymph node, in the spleen, and in the liver at day 7 and prolonged survival after Toxoplasma gondii infection. In addition, IL-17A antibody neutralization reduced inflammation and enhanced survival in BL6 mice. Diminished inflammation is associated with augmented interferon (IFN) gamma serum levels and enhanced production of IL-10 and IFN-gamma in cultured splenocytes upon antigen restimulation. Finally, cyst load and inflammation in the brain at 40 days are greater in surviving BL6 mice than in IL-17RA-deficient mice. In conclusion, oral T. gondii infection increases IL-17 expression and contributes to the inflammatory response, and IL-17 neutralization has a partial protective effect against fatal T. gondii-associated inflammation.