Development of an innovative sub-unit vaccine against toxoplasmosis – NANOTOXO

Nanoparticles used in the NANOTOXO project are made of starch and lipids. The nanoparticles will be coupled to Toxoplasma gondii antigens to generate our vaccine formulation. The formulation will be optimised in term of antigen binding and stability. Studies of the vaccine will be performed in mice in order to elicit an immune response protective against Toxoplasma gondii infection.

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PATENT 1. Betbeder D., Dimier-Poisson I. Ducourneau C.
Pharmaceutical composition for its use in the preventive treatment of infections caused by an intra-cellular pathogen, more particularly Toxoplasma gondii.
European patent N°: 12370002.3-2406 date of filing: 17.09.12

Congenital toxoplasmosis is of considerable economic importance in the livestock industry, because it is one of the principal causes of fetal death, stillbirths and abortion (1 million in Europe every year) in sheep and goat. Primary Toxoplasma infection leads to an immune response that confers lifelong protection against reinfection and against the congenital transmission of toxoplasmosis. Therefore, it should be possible to develop a safe and effective vaccine against acquired and congenital toxoplasmosis.

Presently only one vaccine, based on live attenuated Toxoplasma tachyzoites, has been licensed. However, the possibility exists that it might at some point revert to a pathogenic form, which makes it a poor vaccine candidate for humans.

Moreover, this vaccine is expensive, requires a cold storage for its delivery, causes side effects, is difficult to manufacture and has a short shelf life. In an attempt to overcome these problems, current research is investigating subunit vaccines. Therefore, we are focusing on the conception of a nanoparticle-based subunit vaccine administered intra-nasally.

Feasibility studies with our vaccine have shown it elicits potent, long-lasting humoral and cell-mediated immunity, as well as providing protection. So the aim of this project is to develop an innovative and efficient synthetic vaccine for veterinary use. We expect that this vaccine would reduce or prevent formation of T.gondii tissue cysts, a source of meat contamination for humans. This vaccine should lower the intra-cerebral and intra-muscular cysts and protect pregnant ewe against abortion if they are contaminated during pregnancy. The standardization of the vaccine formulation in term of antigen preparation, binding to nanoparticles, size, stability and immunogenicity will be assessed to select the optimal formulation for animal clinical studies at the end of this 2-year evaluation.