Proteomic study of activated Taenia solium oncospheres

Abstract

Taenia solium cysticerci are a major cause of human seizures and epilepsy in the world. In the gastrointestinal tract of infected individuals, taeniid eggs release the oncospheres, which are then activated by intestinal stimuli, getting ready to penetrate the gut wall and reach distant locations where they transform in cysticerci. Information about oncospheral molecules is scarce, and elucidation of the oncosphere proteome could help understanding the host-parasite relationship during the first steps of infection. In this study, using liquid chromatography and tandem mass spectrometry (LC-MS/MS) analysis, we could identify a set of oncospheral proteins involved in adhesion, protein folding, detoxification and proteolysis, among others. In addition, we have characterized one of the identified molecules, the parasite 14-3-3, by immunoblot and immunolocalization. The identification of these oncospheral proteins represents the first step to elucidate their specific roles in the biology of the host-parasite relationship.

Figure 1

Representative microscopical images (100×) of activated Taenia solium oncospheres. The absence of envelopes (1a, b) and the presence of secretory vesicles (1b) can be seen. H, hooks; SV, secretory vesicles. Bars = 22 μm.

Figure 2

Comparative percentage of the relative abundance of Taenia solium activated oncospheres proteins calculated with the Exponentially Modified Protein Abundance Index (emPAI) and classified into seven functionally-related groups. The figure includes the total percentage of abundance for each functional group, as well as the abundance emPAI number and name of each protein, from the most to the least abundant, in the different groups.

Figure 3

Immunolocalization and immunoblot of the 14-3-3 zeta protein in Taenia solium activated oncospheres. 3a. The mouse anti-14-3-3z serum reacted with the surface of activated oncospheres (D, F). No reactivity was found on oncospheres incubated with a negative mouse serum (B). Images A, C and E show the corresponding images from B, D and F, respectively, under visible light. ES, egg shell; H, hooks. Bars = 10 μm. 3b. The same anti-14-3-3 serum reacted with a band of around 25 kDa by immunoblot in a total extract from activated oncospheres (2). The negative serum showed no reactivity at that molecular weight (3). The banding pattern from the parasite total soluble extract in a 12% polyacrylamide gel stained with silver nitrate is showed in (1). Molecular weight markers are indicated in the left of the figure, in kDa.