New insights into the Manila clam – Perkinsus olseni interaction based on gene expression analysis of clam hemocytes and parasite trophozoites through in vitro challenges
The Manila clam (Ruditapes philippinarum) is the bivalve species with the highest global production from both fisheries and aquaculture, but its production is seriously threatened by perkinsosis, a disease caused by the protozoan parasite Perkinsus olseni. To understand the molecular mechanisms underlying R. philippinarum–P. olseni interactions, we analysed the gene expression profiles of in vitro challenged clam hemocytes and P. olseni trophozoites, using two oligo-microarray platforms, one previously validated for R. philippinarum hemocytes and a new one developed and validated in this study for P. olseni. Manila clam hemocytes were in vitro challenged with trophozoites, zoospores, and extracellular products from P. olseni in vitro cultures, while P. olseni trophozoites were in vitro challenged with Manila clam plasma along the same time-series (1 h, 8 h, and 24 h). The hemocytes showed a fast activation of the innate immune response, particularly associated with hemocyte recruitment, in the three types of challenges. Nevertheless, different immune-related pathways were activated in response to the different parasite stages, suggesting specific recognition mechanisms. Furthermore, the analyses provided useful complementary data to previous in vivo challenges, and confirmed the potential of some proposed biomarkers. The combined analysis of gene expression in host and parasite identified several processes in both the clam and P. olseni, such as redox and glucose metabolism, protease activity, apoptosis and iron metabolism, whose modulation suggests cross-talk between parasite and host. This information might be critical to determine the outcome of the infection, thus highlighting potential therapeutic targets. Altogether, the results of this study aid understanding the response and interaction between R. philippinarum and P. olseni, and will contribute to developing effective control strategies for this threatening parasitosisThis work was funded by the Ministerio de Economía y Competitividad of the Spanish Government, through the projects (AGL2011-30449-C02-01 and AGL2012-37981), the European Regional Development Funds (FEDER 2007–2013) and the Regional Government of Galicia, Xunta de Galicia, Spain, through the projects ED431C 2018/28 and ED431D 2017/21. The study was also supported by the Centro de Supercomputación de Galicia (CESGA). The first author would like to acknowledge the PhD scholarship awarded by the EXPERTS III Consortium of the European Community Mobility Programme “Erasmus Mundus Action 2, Strand 1” (EMA2). SFB was supported by a scholarship of the Consellería do Mar da Xunta de GaliciaS
