Diversity and role of the pathobiome in infection by an invasive parasitIic protist in clam populations – PANIC

Recent studies have shown an impressive increase in the circulation of infectious agents with the emergence of numerous epizootics, zoonoses and epidemics that may result from the introduction of exotic species combined with climate change. The marine micro-parasite Perkinsus olseni (Alveolata) illustrates this phenomenon. Accidentally introduced into Europe in 1972 from Asia with its host, the Manila clam Ruditapes. philippinarum, this parasite has spread along European coasts infecting the exotic clams, R. philippinarum, and the endemic clams R. decussatus. Infection consequences range from sub-lethal effects in clams’ populations in France to recurrent mortality events especially in Portugal for the endemic host species and in Italy for the exotic clams. Distribution of both hosts and parasite, as well as local variations in the disease severity, make this model ideal to consolidate our knowledge of emerging infectious diseases in coastal marine waters under a warming climate context. Amongst the factors modulating host-parasite interactions, the temperature cannot fully explain the different virulence and disease outcomes observed in situ along the European coastline. Indeed, infected hosts harbor an overlooked compartment composed of a complex microbial community (inc. virus, bacteria, eukaryotes), the pathobiome, which could reduce or maximize the pathogenicity of this exotic parasite. This often-neglected compartment undoubtedly plays a key role in the virulence of this parasite and therefore in disease outcomes.
The ANR JCJC PANIC project will test the challenging hypothesis that the pathobiome diversity plays a key role in the modulation of the virulence of exotic parasitic species. Using a multidisciplinary approach ranging from culture, metabarcoding to transcriptomics, this innovative and ambitious project will increase our knowledge, through an integrated view of the host-parasite-pathobiome triptych, of emerging diseases in marine coastal ecosystems in a context of global change.