Background: The transitional period between the oncosphere and the cysticercus of Taenia solium is the postoncospheral (PO) form, which has not yet been completely characterized. The aim of this work was to standardize a method to obtain T. solium PO forms by in vitro cultivation. We studied the morphology of the PO form and compared the expression of antigenic proteins among the PO form, oncosphere, and cysticerci stages. Methodology/Principal Findings: T. solium activated oncospheres were co-cultured with ten cell lines to obtain PO forms, which we studied at three stages of development–days 15, 30, and 60. A high percentage (32%) of PO forms was obtained using HCT-8 cells in comparison to the other cell lines. The morphology was observed by bright field, scanning, and transmission electron microscopy. Morphology of the PO form changed over time, with the six hooks commonly seen in the oncosphere stage disappearing in the PO forms, and vesicles and microtriches observed in the tegument. The PO forms grew as they aged, reaching a diameter of 2.5 mm at 60 days of culture. 15–30 day PO forms developed into mature cysticerci when inoculated into rats. Antigenic proteins expressed in the PO forms are also expressed by the oncosphere and cysticerci stages, with more cysticerci antigenic proteins expressed as the PO forms ages. Conclusions/Significance: This is the first report of an in vitro production method of T. solium PO forms. The changes observed in protein expression may be useful in identifying new targets for vaccine development. In vitro culture of PO form will aid in understanding the host-parasite relationship, since the structural changes of the developing PO forms may reflect the parasite’s immunoprotective mechanisms. A wider application of this method could significantly reduce the use of animals, and thus the costs and time required for further experimental investigations.
Bibliographical noteFunding Information:
This work was financially supported by: MV is supported by the Fondo para la Innovaci?n, Ciencia y Tecnolog?a FINCyT grant Contrato N? 129- FINCyT-IB-2013, http://www.fincyt.gob.pe/site/index. php; NC is supported by The Fogarty International Clinical Research Scholars and Fellows Program at Vanderbilt University grant R24 TW007988, http:// fogartyscholars.org/; HHG is supported by Bill and Melinda Gates Foundation?Cysticercosis Elimination in Peru grants 23981 and 33848, Training in Infectious Diseases in Peru grant FIC/NIH D43 TW001140 (http://grantome.com/grant/NIH/D43- TW001140-14) and Wellcome Trust Senior International Research Fellowship in Public Health and Tropical Medicine (http://www.wellcome.ac.uk/ index.htm); and RHG is supported by Infectious Diseases Training Program in Peru grant 5D43TW006581 (https://www.collectiveip.com/grants/ NIH:8248228). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
© 2016 Chile et al.