Proteomic profiling of hydatid fluid from pulmonary cystic echinococcosis

Abstract

Background: Most cystic echinococcosis cases in Southern Brazil are caused by Echinococcus granulosus and Echinococcus ortleppi. Proteomic studies of helminths have increased our knowledge about the molecular survival strategies that are used by parasites. Here, we surveyed the protein content of the hydatid fluid compartment in E. granulosus and E. ortleppi pulmonary bovine cysts to better describe and compare their molecular arsenal at the host-parasite interface.

Methods: Hydatid fluid samples from three isolates of each species were analyzed using mass spectrometry-based proteomics (LC-MS/MS). In silico functional analyses of the identified proteins were performed to examine parasite survival strategies.

Results: The identified hydatid fluid protein profiles showed a predominance of parasite proteins compared to host proteins that infiltrate the cysts. We identified 280 parasitic proteins from E. granulosus and 251 from E. ortleppi, including 52 parasitic proteins that were common to all hydatid fluid samples. The in silico functional analysis revealed important molecular functions and processes that are active in pulmonary cystic echinococcosis, such as adhesion, extracellular structures organization, development regulation, signaling transduction, and enzyme activity.

Conclusions: The protein profiles described here provide evidence of important mechanisms related to basic cellular processes and functions that act at the host-parasite interface in cystic echinococcosis. The molecular tools used by E. granulosus and E. ortleppi for survival within the host are potential targets for new therapeutic approaches to treat cystic echinococcosis and other larval cestodiases.

Keywords: Echinococcus granulosus; Echinococcus ortleppi; Host-parasite interface; Hydatid fluid; Parasite proteomics; Secretome.

Fig. 1

Parasitic proteins identified in HF samples from pulmonary cystic echinococcosis. Venn diagrams showing the number of proteins identified: a in E. granulosus biological replicates; b in E. ortleppi biological replicates; c in each species or shared between them. The overall numbers of proteins detected are indicated below the sample/species identification

Fig. 2

In silico prediction of secretion pathways. Percentages of the total and absolute number of proteins in E. granulosus and E. ortleppi HF repertoires with probable classic or alternative signals for secretion are presented. Proteins with any identifiable signal for secretion were grouped under the term “Unidentified secretion pattern.” a E. granulosus HF proteins. b E. ortleppi HF proteins

Fig. 3

Summarized functional classification of proteins identified in E. granulosus HF. Scatterplot view of REVIGO category clusters of related GO terms obtained in functional enrichment analysis. a Biological process category clusters. b Molecular function category clusters. Sphere size is proportional to the P-value (larger spheres indicate more significant P-values, according to the scale)

Fig. 4

Summarized functional classification of proteins identified in E. ortleppi HF. Scatterplot view of REVIGO category clusters of related GO terms obtained in functional enrichment analysis. a Biological process category clusters. b Molecular function category clusters. Sphere size is proportional to the P-value (larger spheres indicate more significant P-values, according to the scale)