Comparative proteomic profiling reveals specific adaption of Vibrio anguillarum to oxidative stress, iron deprivation and humoral components of innate immunity.

Abstract The gram-negative bacterium Vibrio (Listonella) anguillarum (VA) is the causative agent of vibriosis, a. terminal hemorrhagic septicemia affecting the aquacultural industry across the globe. In the current study we used comparative label-free quantitative proteomics to investigate how VA adapts to conditions that mimic defined aspects of vibriosis-related stress such as exposure to oxidative stress (H2O2), opsonization with complement factors through incubation with Atlantic salmon serum, and iron deprivation upon supplementation of 2,2′-dipyridyl (DIP) to the growth medium. We also investigated how regulation of virulence factors may be governed by the VA growth phase and availability of nutrients. All conditions investigated revealed stress-specific proteomic adaption and only nine proteins were found to be commonly regulated in all conditions. Notably, iron deprivation and exposure to Atlantic salmon serum both evoked upregulation of iron acquisition mechanisms. A general observation made for all stress-related conditions was regulation of multiple metabolic pathways. The findings made in the present study represent a source of potential virulence determinants that can be of use in the search for means to avoid/control vibriosis. Significance Vibriosis in fish and shellfish caused by V. anguillarum is responsible for large economic losses in the aquaculture sector across the globe. However, not much is known about the defense mechanism of this pathogen to percept and adapt to the imposed stresses during infection. Analyzing the response of V. anguillarum to multiple host-related physiochemical stresses, the quantitative proteomic analysis of the present study indicates modulation of several virulence determinants and key defense networks of this pathogen. Our findings provide a theoretical basis to enhance our understanding of V. anguillarum - host interactions and can be employed to improve current intervention strategies to control vibriosis in aquaculture.