Identification of proteome, antigen protein and antigen membrane protein from Spiroplasma eriocheiris

Spiroplasma eriocheiris, which causes tremor disease in Chinese mitten crab Eriocheir sinensis, has led to huge economic losses in aquaculture. Immunoproteomics, a new scientific technique combining proteomics and immunological analytical methods, provided the direction of our research on S. eriocheiris. The aim of our study was to identify the proteome, antigen proteins and antigen membrane proteins of S. eriocheiris. A total of 780 S. eriocheiris proteins were identified by the LC-MS/MS technique. Based on immunoproteomics, 51 proteins and 7 proteins in S. eriocheiris were identified by anti-S. eriocheiris serum and negative serum respectively (six proteins in common). Thus, 45 antigenic proteins in S. eriocheiris were identified; among them, molecular chaperone DnaK, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), ATP synthase subunit beta and enolase can be considered as immunogenic proteins. Similarly, 32 membrane proteins and 6 membrane proteins were identified by anti-S. eriocheiris serum and negative serum respectively (two proteins in common). Thus, 30 antigenic membrane proteins in S. eriocheiris were identified; three of them have been reported as surface proteins including pyruvate kinase, enolase and GAPDH. All of these proteins may play key roles in the pathogeny and can be used in the future for diagnoses and prevention.

Spiroplasma eriocheiris is a novel pathogen causing the tremor disease in Chinese mitten crab Eriocheir sinensis. This is the first time LC-MS/MS was used to identify the proteome, antigen protein and antigen membrane protein of S. eriocheiris. The results can certainly provide valuable information towards the identification of virulent proteins or diagnosis of pathogenic mechanisms.