Deciphering the impact of MreB on the morphology and pathogenicity of the aquatic pathogen Spiroplasma eriocheiris.

Background: Spiroplasma eriocheiris has been proved to be a pathogen causing tremor disease of Eriocheir sinensis, it is also infectious to other aquatic crustaceans, resulting in a serious threat on the sustainable development of the aquaculture industry. S. eriocheiris is a helical-shaped microbe without a cell wall, and its motility is related to the cytoskeleton protein MreB which belongs to the actin superfamily and has five MreB homologs.

Results: In this study, we purified MreB3, MreB4 and MreB5, and successfully prepared monoclonal antibodies. After S. eriocheiris treated with actin stabilizator Phalloidin and inhibitors A22, we found that Phalloidin and A22 affect the S. eriocheiris morphology by altering MreB expression. We confirmed that the ability of S. eriocheiris to invade E. sinensis was increased after treatment with Phalloidin, including that the morphology of E. sinensis blood lymphocytes was deteriorated, blood lymphocytes viability was decreased, peroxidase activity and cell necrosis were increased. On the contrary, the pathogenicity of S. eriocheiris decreased after treatment with A22.

Conclusions: Our findings suggest that the MreB protein in S. eriocheiris plays a crucial role in its morphology and pathogenicity, providing new insights into potential strategies for the prevention and control of S. eriocheiris infections.