Integrative RNA-Seq analysis of host-parasite interactions and microbiota shifts in the gills of two fish species infected with monogeneans.

Monogenean infections represent a significant threat to aquaculture by compromising fish health. These parasites can cause severe histological damage and increase mortality rates. The white snook (Centropomus viridis) and the gilthead seabream (Sparus aurata) are two commercially important fish species that become susceptible to diseases when infected with monogeneans. Understanding the molecular mechanisms underlying host responses to infection is essential for developing effective disease management strategies. In this study, we performed an integrative RNA-Seq analysis using transcriptomic datasets from C. viridis and S. aurata infected with the monogeneans Rhabdosynochus viridisi and Sparicotyle chrysophrii, respectively. These datasets originate from three studies, allowing us to investigate host gene expression changes, monogenean gene activation, and microbiota shifts associated with infection. Our analysis of the gill microbiota revealed significant alterations in bacterial composition between infected and uninfected fish. In the microbiota of both C. viridis and S. aurata, eight bacterial families were more abundant in infected fish, whereas eleven and four families, respectively, were more abundant in uninfected fish. In monogeneans, the molecular mechanisms shared across all Bioprojects included extracellular matrix organization, proteolysis, and gluconeogenesis, processes that may be involved in parasite colonization and survival within the host. In fish, our analysis identified shared molecular mechanisms between S. aurata and C. viridis, including oxygen carrier activity, cytokine regulation, bacterial response, and cadherin-mediated adhesion, highlighting a complex interplay between the host immune system, microbiota, and parasite. These findings enhance our understanding of fish-microbiome-parasite interactions and offer valuable perspectives for improving disease control strategies in aquaculture.