Virulence mechanisms of bacterial aquaculture pathogens and antivirulence therapy for aquaculture

Abstract

Although aquaculture continues to be the fastest-growing food-producing industry worldwide, the sector faces important challenges with respect to controlling infectious diseases. Indeed, the frequent use of antibiotics, which are traditionally the most important line of defence against bacterial disease, has raised problems related to the development and spread of resistance. As a result, we currently are in a race to develop novel therapeutics that should allow us to continue controlling bacterial disease in the future. In this respect, scientific progress of the past years has allowed us to start understanding the mechanisms by which bacterial pathogens are causing disease. This knowledge in its turn opens up novel possibilities to combat infections by interfering with these mechanisms, a strategy that has been termed antivirulence therapy. In this review, the current knowledge with respect to pathogenicity mechanisms of bacterial aquaculture pathogens is discussed, including adhesion mechanisms, production of extracellular polysaccharides and biofilm formation, production of lytic enzymes (e.g. haemolysins and proteases), mechanisms of iron acquisition, secretion systems and regulatory mechanisms such as quorum sensing and host–pathogen signalling with catecholamine stress hormones. Furthermore, an overview is given of the first steps towards antivirulence therapy for aquaculture, with a focus on quorum sensing disruption as a proof of concept.