Proteomic Analysis of Schistosoma mansoni Cercarial Secretions

Abstract

Schistosomiasis is a global health problem caused by several species of schistosome blood flukes. The initial stage of infection is invasion of human skin by a multicellular larva, the cercaria. We identified proteins released by cercariae when they are experimentally induced to exhibit invasive behavior. Comparison of the proteome obtained from skin lipid-induced cercariae (the natural activator), a cleaner mechanical induction procedure, and an uninduced proteomic control allowed identification of protein groups contained in cercarial acetabular gland secretion versus other sources. These included a group of proteins involved in calcium binding, calcium regulation, and calcium-activated functions; two proteins (paramyosin and SPO-1) implicated in immune evasion; and protease isoforms implicated in degradation of host skin barriers. Several other protein families, traditionally found as cytosolic proteins, appeared concentrated in secretory cells. These included proteins with chaperone activity such as HSP70, -86, and -60. Comparison of the three experimental proteomes also allowed identification of protein contaminants from the environment that were identified because of the high sensitivity of the MS/MS system used. These included proteins from the intermediate host snail in which cercariae develop, the investigator, and the laboratory environment. Identification of proteins secreted by invasive larvae provides important new information for validation of models of skin invasion and immune evasion and aids in rational development of an anti-schistosome vaccine.

Proteomic analysis of Schistosoma mansoni egg secretions

“…Previously identified egg-specific glycoproteins (IPSE/ alpha-1, omega-1, kappa-5) were positively identified as components of ESP, and yet some of the most abundant proteins are still relatively uncharacterized. A comparison of our proteomic identification of egg secreted proteins and the results of both peptide mass fingerprinting of SEA [42] and cercarial secretions [39] revealed that many proteins were identified in all three studies: 14-3-3 proteins, actin, enolase, GAPDH, HSP70, thioredoxin, and GST −26K and −28K. However, in this study we also identified protein components not previously identified in parasitic secretions including NPC2 and venom allergen-like proteins.…”

“…The gene ontology of the most-abundant egg secreted proteins (22 proteins comprising 50% of total ESP) was compared to the ontology of both the entire complement of egg secreted proteins (188 proteins, 100% of ESP) and the ontology of annotated Schistosoma mansoni proteins in the NCBI nonredundant database, as analyzed by the GOblet server previously (650 proteins, [39]). Table 2 displays the results of GO annotation for the three major categories of molecular function, biological process, and cellular component.…”

Schistosomes—proteomics studies for potential novel vaccines and drug targets

“…The first study [55] has utilized 1D SDS-PAGE LC-MS/MS to analyze secretions from stimulated S. mansoni cercariae, using either human skin lipid stimulation or tail shearing transformation by passages through a syringe; also noninduced cercariae were used. The authors identified 72, 85 and 15 proteins that were secreted by cercariae submitted to these three conditions, respectively [55]. In the lipid-stimulated sample 12 glycolytic enzymes, six previous vaccine candidates and three cercarial elastases were detected [55].…”

“…The authors identified 72, 85 and 15 proteins that were secreted by cercariae submitted to these three conditions, respectively [55]. In the lipid-stimulated sample 12 glycolytic enzymes, six previous vaccine candidates and three cercarial elastases were detected [55]. A second study [31] has utilized S. mansoni cercariae mechanically transformed by vortexing, followed by incubation in culture medium.…”

Excretory/Secretory Proteome of the Adult Developmental Stage of Human Blood Fluke, Schistosoma japonicum

“…Importantly this information can be expected to facilitate the discovery of vaccines and new therapeutic drug targets as well as new diagnostic reagents for schistosomiasis control. Proteomics approaches encompass the most efficient and powerful tools for identification of protein complexes and have been widely used to decipher the ES components of the filarial parasite Brugia malayi (19), Leishmania (Trypanosomatidae) (20), nematodes (21)(22)(23)(24)(25)(26), and Trematoda (27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37). For the genus Schistosoma, the ES compositions of S. mansoni have been identified in many developmental life stages, including sporocyst (34), cercaria (35,36), and egg (37) but have not been characterized in the adult worm.…”