STRIP

The emergence of foodborne parasites, such as the protozoa Cryptosporidium spp. and Toxoplasma gondii, is greatly favored by changing in eating habits towards fresh and minimally processed food, the global trade of foodstuffs, changes in food production systems and the increased number of sensitive people. Foodborne transmission of Cryptosporidium spp. and Toxoplasma gondii greatly depends on the ability of their oocyst forms to remain infective in food matrices in spite of external stresses combined to food characteristics. We hypothesize that oocysts are able to remain infective in foods by adapting their biological functions (structure and metabolism) at the cellular and/or molecular levels, and that food matrices can modify this response and the ability of the parasites to survive. In this context, the first objective of the STRIP project is to characterize, following a multidisciplinary approach, the biological response of oocysts submitted to selected stresses encountered by these parasites in food matrices (pH variations, reducing conditions) or following exposure to chemical disinfectants (chlorine, ozone) as applied in minimally-processed vegetables (MPV) industries. The oocyst response will be evaluated regarding (i) the structure, mechanics, and biochemistry of the oocyst wall and its possible interaction with host cells, (ii) the ability of oocysts to remain viable and infective, and (iii) the potential of the oocysts to adapt their metabolism to retain their infectivity. A second objective is to evaluate the impact of oxidative stress, at a pilot-scale, on the survival of oocysts associated to food matrices (leafy green vegetables). To reach these objectives, we will implement innovative imaging, biophysical, and ‘omic’ technologies coupled to viability and infectivity assays (RT-qPCR techniques, animal and cell culture assays). This tools and methodologies will provide an unprecedented characterization of the molecular and cellular mechanisms by which Cryptosporidium and T. gondii oocysts resist to stresses and retain their infectivity in food. The new important basic knowledge generated by the STRIP project will benefit to the field of food parasitology by providing for the first time a response-wide overview to stresses of these parasites, and to the 'agro-food' sector, in particular MPV industries, in order to implement innovative control measures, such as ozone-based technologies. We expect that the STRIP project contribute to a better risk assessment and management of these emerging foodborne parasitic pathogens in a context of global trade.