Sialic acid catabolism contributes to Vibrio mimicus virulence

Abstract

Vibrio mimicus is an emerging pathogen primarily associated with catfish vibriosis. Infectious caused by V. mimicus in aquatic animals have been characterized by a short infection course and high mortality rate, resulting in significant economic losses. The utilization of sialic acid has been shown to be correlated with bacterial virulence, particularly in highly sialylated environments. In this study, we investigated virulence-determining phenotypes of V. mimicus strain SCCF01 (WT) and the sialic acid catabolism (SaCS) defect strain ΔSaCS, and revealed their potential molecular connections by comparative proteomics analysis. Our results showed that abrogation of sialic acid catabolism ability resulted in bacterial morphological changes, a decrease in biofilm formation, but an increase in cell adherence ability. Animal experiments confirmed that SaCS contributes to V. mimicus pathogenicity, as the LD50 of ΔSaCS strain was 27-fold lower compared to WT strain. Proteomics analysis revealed that differentially expressed proteins between the culture supernatants of WT and ΔSaCS were mainly enriched in pentose phosphate pathway, purine metabolism and bacterial chemotaxis. The ΔSaCS lacked several extracellular proteins and virulence factors, providing additional explanation for its attenuating effect.