Abstract
The most commonly used serodiagnostic antigens for trichinellosis are the excretory-secretory (ES) antigens from T. spiralis muscle larvae (ML), but the specific antibodies against the ML ES antigens are usually negative during early stage of Trichinella infection. The recent studies demonstrated that T. spiralis adult worm (AW) antigens were recognized by mouse or swine infection sera on Western blot as early as 7–15 days post-infection (dpi), the AW antigens might contain the early diagnostic markers for trichinellosis. The purpose of this study was to screen early diagnostic antigens in T. spiralis AW ES proteins recognized by sera of early patients with trichinellosis. T. spiralis AW were collected at 72 h post-infection (hpi), and their ES antigens were analyzed by SDS-PAGE and Western blot. Our results showed that 5 protein bands (55, 48–50, 45, 44, and 36 kDa) were recognized by sera of early patients with trichinellosis collected at 19 dpi, and were subjected to shotgun LC–MS/MS and bioinformatics analyses. A total of 185 proteins were identified from T. spiralis protein database, of which 116 (67.2%) proteins had molecular weights of 30∼60 kDa, and 125 (67.6%) proteins with pI 4–7. Bioinformatic analyses showed that the identified proteins have a wide diversity of biological functions (binding of nucleotides, proteins, ions, carbohydrates, and lipids; hydrolase, transferase, and oxidoreductase, etc.). Several enzymes (e.g., adult-specific DNase II, serine protease and serine protease inhibitor) could be the invasion-related proteins and early diagnostic markers for trichinellosis. Moreover, recombinant T. spiralis serine protease (rTsSP-ZH68) was expressed in E. coli and its antigenicity was analyzed by Western blot with the early infection sera. The rTsSP-ZH68 was recognized by sera of infected mice at 8–10 dpi and sera of early patients with trichinellosis at 19 dpi. T. spiralis AW proteins identified in this study, especially serine protease, are the promising early diagnostic antigens and vaccine candidates for trichinellosis.
Highlights
Trichinella spiralis, an intracellular parasitic nematode, can cause a serious foodborne trichinellosis
Trichinella spiralis adult worm (AW) ES proteins were separated by SDS-PAGE
The results demonstrated that the AW ES proteins had 25 bands with a MW ranging from 15 to 97 kDa (Figure 1A)
Summary
Trichinella spiralis, an intracellular parasitic nematode, can cause a serious foodborne trichinellosis. Humans acquire trichinellosis by ingesting raw or undercooked meat (mainly pork) that contains the infective larvae of Trichinella (Murrell, 2013). Human trichinellosis has been reported in 55 countries of the world and is considered as a re-emerging disease (Pozio, 2007). From 1986 to 2009, there were 65,818 cases and 42 deaths reported from 41 countries (Murrell and Pozio, 2011). Trichinellosis can lead to death, in elderly patients accompany with neurological or cardiovascular complications. It is difficult to diagnose the human trichinellosis on the basis of clinical manifestations of the patients. It is difficult to diagnose the human trichinellosis on the basis of clinical manifestations of the patients. (Dupouy-Camet et al, 2002)
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