Preliminary characterization of an adult worm “vomit” preparation of Schistosoma mansoni and its potential use as antigen for diagnosis

Abstract

Schistosoma mansoni is a parasitic trematode of the portal-mesenteric veins with a closed-end intestine. Adult worms regurgitate their intestinal content after digestion, together with constituents of the lining gut. Some of these molecules circulate in the blood and are antigenic. We obtain a "vomit" preparation and preliminary evaluate its biochemical composition and antigenic capacity. The "vomit" preparation was obtained after changes in temperature and solutions of incubation of adult worms between 4 and 37 degrees C. Supernatant was assayed for protein, carbohydrate concentration and enzymatic activities associated to the intestine and to the worm tegument. The antigenicity of the product was evaluated using Western blot (WB) analysis against sera of experimentally infected mice, before and after drug cure, sera from people infected with S. mansoni and from individuals infected with other parasitoses. More carbohydrate than protein was detected in the preparations. Cysteine proteinase (CP), N-acetyl-beta-D: -glucosaminidase and alkaline phosphatase activities were detected. The latter enzyme activity is a marker of the tegument, suggesting that in spite of careful conditions used to avoid the presence of tegumental material, manipulation of the worms always resulted in the release of tegumental molecules. Cationic exchange chromatography was useful to separate various components of this "vomit" preparation, particularly enzymes responsible for CP activity. Two highly immunogenic and specific duplets were observed in the WB analysis, 31/32- and 38/40-kDa components, the former probably referring to the intestinal CPs Sm31/Sm32. None of the two duplets disappeared after successful chemotherapy during the time of evaluation in mice or humans.

Comparative sensitivities of various tests for diagnosing early Schistosoma mansoni infection in mice

“…The present results clearly demonstrated that CS sensitivity to detect IgG in plasma of S. mansoni infected mice was generally higher than that of WoV which contrasted the previous study that compared the sensitivity of the two antigens to detect IgG in sera of infected humans residing in an endemic area in Burkina Faso [15]. Furthermore, antibodies against certain antigens present in the worm intestine, may take longer time to disappear [24].…”

Schistosome Feeding and Regurgitation

“…However, worms in vitro are rarely seen voiding Hz unless they are subjected to a chemical, osmotic, or temperature shock [11], [63], [64]. Indeed, the one direct series of observations on adult worms in the intestinal vasculature of mice [31] makes no mention of Hz regurgitation.…”

“…Instead, intense motor activity in the anterior gut, followed by relaxation of the esophageal wall muscles, resulted in the movement of a thin dark line of vomitus up the esophageal lumen and out through the mouth [26] (Figure 3D). It is unclear whether Hz can be selectively eliminated during regurgitation, while important cathepsins, peptidases, saposins, and a variety of carrier protein homologs are retained [11], [63], [64]. However, the Hz expelled into the bloodstream of infected animals [65], [66] has been proposed to exert an immunomodulatory effect on the host [67].…”

Induction of protective immune responses against schistosomiasis using functionally active cysteine peptidases

“…More recently, using microarray analysis, Gobert et al (2010) showed that genes encoding cathepsin B and cathepsin L were greatly up-regulated in S. mansoni larvae cultured for 5 days (65 and 37-fold, respectively). Both SmCBs and SmCLs are highly immunogenic in infected mice and antibodies are detected in sera of S. mansoni -infected patients (Dalton et al, 1995; Dalton and Brindley, 1996; Planchart et al, 2007; Sulbarán et al, 2010). …”