Mouse model of secondary cystic echinococcosis.

Cystic echinococcosis (CE) is a parasitic zoonosis caused by the larval stage of the cestode Echinococcus granulosus sensu lato (s. l.), a genetic complex composed of five species: E. granulosus sensu stricto (s. s.), E. equinus, E. ortleppi, E. canadensis, and E. felidis. The parasite requires two mammalian hosts to complete its life cycle: a definitive host (mainly dogs) harboring the adult parasite in its intestines, and an intermediate host (mostly farm and wild ungulates) where hydatid cysts develop mainly in the liver and lungs. Humans are accidental intermediate hosts, being susceptible to either primary or secondary forms of CE; the first one due to the ingestion of oncospheres, and the second one because of the spillage of protoscoleces (PSC) contained within a primary cyst. Secondary CE is a serious medical problem, and can be modeled in immunocompetent mice (a non-natural intermediate host) through the intraperitoneal inoculation of viable PSC from E. granulosus s. l. This model is useful to study not only the immunobiology of CE, but also to test new chemotherapeutics or therapeutical protocols, to explore novel vaccine candidates, and to evaluate alternative diagnostic and/or follow-up tools. The mouse model of secondary CE involves two sequential stages: an early stage of parasite pre-encystment (PSC develop into hydatid cysts in the peritoneal cavity of mice), and a late or chronic stage of parasite post-encystment (already differentiated cysts slowly grow during the whole host lifespan). This model is a time-consuming infection, whose outcome depends on several factors like the parasite infective dose, the mouse strain, and the parasite species/genotype. Thus, such variables should always be adjusted according to the research objectives. Herein, the general materials and procedures needed to establish secondary CE in mice are described, as well as several useful tips and recommendations.

Using the model cestode Taenia crassiceps for the study of cysticercosis.

Taenia solium is the aetiological agent of taeniasis/cysticercosis, one of the most severe neglected tropical diseases (NTD) according to the World Health Organization (WHO). The life cycle of T. solium alternates between pigs (intermediate host) and humans (definitive host). In addition, humans can act as accidental intermediate hosts if they ingest infective eggs. In this case, the most severe condition of the disease occurs when parasites invade the central nervous system, causing neurocysticercosis (NCC). The complexity of the life cycle of T. solium imposes a barrier to study this pathogen thoroughly. Thus, related species, such as T. crassiceps are commonly used. Due to its capacity to multiply asexually, T. crassiceps can be maintained by serial passage in laboratory mice in standard biosecurity level facilities. In addition, an in vitro system to generate cysticerci in the presence of feeder cells has been recently developed. Despite model species display biological differences with their zoonotic counterparts, they have historically helped to understand the biology of the related pathogenic species and hence, generate improvements in NTD detection and control. In this chapter, we describe the procedures to carry out both in vivo and in vitro systems for T. crassiceps in the laboratory.

A Comparative Analysis of the Protein Cargo of Extracellular Vesicles from Helminth Parasites.

Helminth parasites cause debilitating-sometimes fatal-diseases in humans and animals. Despite their impact on global health, mechanisms underlying host-parasite interactions are still poorly understood. One such mechanism involves the exchange of extracellular vesicles (EVs), which are membrane-enclosed subcellular nanoparticles. To date, EV secretion has been studied in helminth parasites, including EV protein content. However, information is highly heterogeneous, since it was generated in multiple species, using varied protocols for EV isolation and data analysis. Here, we compared the protein cargo of helminth EVs to identify common markers for each taxon. For this, we integrated published proteomic data and performed a comparative analysis through an orthology approach. Overall, only three proteins were common in the EVs of the seven analyzed species. Additionally, varied repertoires of proteins with moonlighting activity, vaccine antigens, canonical and non-canonical proteins related to EV biogenesis, taxon-specific proteins of unknown function and RNA-binding proteins were observed in platyhelminth and nematode EVs. Despite the lack of consensus on EV isolation protocols and protein annotation, several proteins were shown to be consistently detected in EV preparations from organisms at different taxa levels, providing a starting point for a selective biochemical characterization.

Primera identificación de Echinococcus vogeli en una paca en la provincia de Misiones, Argentina / [First report of Echinococcus vogeli in a paca in Misiones province, Argentina].

We report the first finding of Echinococcus vogeli in a paca, Cuniculus paca, in the tropical forest of Misiones, in the north of Argentina. The presence of the bush dog, Speothos venaticus, E. vogelís only natural definitive host, was also reported. The polycystic hydatids, 2 to 3 cm in diameter, were only found in the liver of an adult paca. The size range of the hooks and the relative proportion blade/handle did not show significant differences with respect to the ones reported for E. vogeli. The size of E. granulosus hooks, measured for comparison purposes, was significantly smaller (p E. vogeli in Argentina. The probability of finding neotropical echinococcosis in humans reinforces the need to expand the search for E. vogeli in Argentina. Echinococcosis due to E. vogeli is very aggressive and may cause death in about a third of the human population affected.