iTRAQ-based differential proteomic analysis of high- and low-virulence strains of Spiroplasma eriocheiris.

Spiroplasma eriocheiris is one of the major pathogenic bacteria in crustaceans, featuring high infectivity, rapid transmission, and an absence of effective control strategies, resulting in significant economic losses to the aquaculture industry. Research into virulence-related factors provides an important perspective to clarify how Spiroplasma eriocheiris is pathogenic to shrimps and crabs. Therefore, in this study, isobaric tags for relative and absolute quantitation (iTRAQ) technology was utilized to undertake a differential proteomic analysis of high- and low-virulence Spiroplasma eriocheiris strains at different growth phases. A total of 868 differentially expressed proteins (DEPs) were obtained, of which 31 novel proteins were identified by proteogenomic analysis. There were 62, 61, 175, and 235 DEPs between the log phase (YD) and non-log phase (YFD) of the high-virulence strain, between the log phase (CD) and non-log phase (CFD) of the low-virulence strain, between YD and CD, and between CFD and YFD, respectively. All the DEPs were compared with virulence protein databases (MvirDB and VFDB), and 68 virulence proteins of Spiroplasma eriocheiris were identified, of which 12 were involved in a total of 21 metabolic pathways, including motility, chemotaxis, growth, metabolism and virulence of the bacteria. The results of this study form the basis for further research into the molecular mechanism of virulence and physiological differences between high- and low-virulence strains of Spiroplasma eriocheiris, and provide a scientific basis for a detailed understanding of its pathogenesis.