Characterization of the Secreted Acid Phosphatase SapS Reveals a Novel Virulence Factor of That Contributes to Survival and Virulence in Mice

possesses a large arsenal of immune-modulating factors, enabling it to bypass the immune system's response. Here, we demonstrate that the acid phosphatase SapS is secreted during macrophage infection and promotes its intracellular survival in this type of immune cell. In animal models, the SA564 mutant demonstrated a significantly lower bacterial burden in liver and renal tissues of mice at four days post infection in comparison to the wild type, along with lower pathogenicity in a zebrafish infection model. The SA564 mutant elicits a lower inflammatory response in mice than the wild-type strain, while cells harbouring a functional induce a chemokine response that favours the recruitment of neutrophils to the infection site. Our and quantitative transcript analysis show that SapS has an effect on capacity to adapt to oxidative stress during growth. SapS is also involved in biofilm formation. Thus, this study shows for the first time that SapS plays a significant role during infection, most likely through inhibiting a variety of the host's defence mechanisms.