Dual RNA-seq analyses provide insights into the biology of the fish pathogen Piscirickettsia salmonis

After invasion, P. salmonis actively replicates in macrophages and monocytes, and its ability to enter and multiply within host cells is essential for pathogenesis. The ability of P. salmonis to subvert the functions of macrophages contributes to bacteria survival and dissemination within the host.

Here, we adapted dual RNA-sequencing to define how P. salmonis remodel their gene expression in tandem with that of infected the host cell, a macrophage-like cell line from Salmo salar head kidney, known as SHK1. We found that SHK1 cells increased lysosomal content and activity to defend against invading bacteria, while P. salmonis upregulated gene functions related to virulence, including type IV secretion system (T4SS), iron acquisition, transport and efflux systems.