Early mucosal responses in blue catfish (Ictalurus furcatus) skin to Aeromonas hydrophila infection.

Bacterial pathogens are well-equipped to detect, adhere to, and initiate infection in their finfish hosts. The mucosal surfaces of fish, such as the skin, function as the front line of defense against such bacterial insults that are routinely encountered in the aquatic environment. While recent progress has been made, and despite the obvious importance of mucosal surfaces, the precise molecular events that occur soon after encountering bacterial pathogens remain unclear. Indeed, these early events are critical in mounting appropriate responses that ultimately determine host survival or death. In the present study, we investigated the transcriptional consequences of a virulent Aeromonas hydrophila challenge in the skin of blue catfish, Ictalurus furcatus. We utilized an 8×60K Agilent microarray to examine gene expression profiles at key early timepoints following challenge (2 h, 12 h, and 24 h). A total of 1155 unique genes were significantly altered during at least one timepoint. We observed dysregulation in a number of genes involved in diverse pathways including those involved in antioxidant responses, apoptosis, cytoskeletal rearrangement, immunity, and extracellular matrix protein diversity and regulation. Taken together, A. hydrophila coordinately modulates mucosal factors across numerous cellular pathways in a manner predicted to enhance its ability to adhere to and infect the blue catfish host.