Abstract
BackgroundThe excretory-secretory (ES) proteins of Trichinella spiralis muscle larvae (ML) come mainly from the excretory granules of the stichosome and the cuticles (membrane proteins), are directly exposed to the host’s immune system, and are the main target antigens, which induce the immune responses. Although the ES proteins are the most commonly used diagnostic antigens for trichinellosis, their main disadvantage are the false negative results during the early stage of infection. The aim of this study was to identify early specific diagnostic antigens from the main components of T. spiralis muscle larval ES proteins.MethodsTwo-dimensional electrophoresis (2-DE) combined with Western blot were used to screen the early diagnostic antigens from the main components of T. spiralis muscle larval ES proteins. The protein spots recognized by the sera from BALB/c mice infected with T. spiralis at 18 days post-infection (dpi) were identified by MALDI-TOF/TOF-MS and putatively annotated using GO terms obtained from the InterPro databases.ResultsThe ES proteins were analyzed by 2-DE, and more than 33 protein spots were detected with molecular weight varying from 40 to 60 kDa and isoelectric point (pI) from 4 to 7. When probed with the sera from infected mice at 18 dpi, 21 protein spots were recognized and then identified, and they were characterized to correlate with five different proteins of T. spiralis, including two serine proteases, one deoxyribonuclease (DNase) II, and two kinds of trypsin. The five proteins were functionally categorized into molecular function and biological process according to GO hierarchy.Conclusions2-DE and Western blot combined with MALDI-TOF/TOF-MS were used to screen the diagnostic antigens from the main components of T. spiralis muscle larval ES proteins. The five proteins of T. spiralis identified (two serine proteases, DNase II and two kinds of trypsin) might be the early specific diagnostic antigens of trichinellosis.
Highlights
The excretory-secretory (ES) proteins of Trichinella spiralis muscle larvae (ML) come mainly from the excretory granules of the stichosome and the cuticles, are directly exposed to the host’s immune system, and are the main target antigens, which induce the immune responses
We identified the early specific diagnostic antigens from the main components of T. spiralis ML ES proteins using immunoproteomic methods
Previous studies demonstrated that all true positive sera, reacted with a three-band pattern ranging in size from 48–72 kDa using ES antigens of T. spiralis ML [38]
Summary
The excretory-secretory (ES) proteins of Trichinella spiralis muscle larvae (ML) come mainly from the excretory granules of the stichosome and the cuticles (membrane proteins), are directly exposed to the host’s immune system, and are the main target antigens, which induce the immune responses. The ES proteins are the most commonly used diagnostic antigens for trichinellosis, their main disadvantage are the false negative results during the early stage of infection. The aim of this study was to identify early specific diagnostic antigens from the main components of T. spiralis muscle larval ES proteins. Serologic tests [e.g., enzyme-linked immunosorbent assay (ELISA) using muscle larval excretory-secretory (ES) antigen or the synthetic antigen 3,6-dideoxy-D-arabinohexose (tyvelose)] for detecting the specific anti-Trichinella antibody IgG are not positive in pigs and mice infected experimentally until 3–4 weeks after infection [11,12,13]. The detection of IgG antibodies to Trichinella by ELISA using ES antigens of T. spiralis muscle larvae (ML) is commonly used for diagnosis of trichinellosis [9]. The main disadvantage of detection of IgG antibodies is the occurrence of a high rate of false negative results during the early stage of infection. An attempt is made to screen early specific antigens from the most abundant proteins of T. spiralis ML ES proteins, which might be valuable for the early diagnosis of trichinellosis
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