Chimeric oil bodies as an alternative delivery system for peptide vaccines
Author(s)
Capuano, Floriana
Date Issued
February 24, 2009
Type
Doctoral Thesis
Abstract
Transgenic plants have potential advantages over conventional expression systems for the production of recombinant antigens for the formulation of subunit vaccines. In particular, seed-targeted expression is attractive as proteins can stably accumulate. However, the purification of recombinant proteins from seeds may be difficult due to the complex spectrum of proteins present in this plant organ.
The oleosin fusion technology represents an efficient method to simplify the purification of recombinant proteins from seeds. Oleosins are hydrophobic plant proteins embedded in small, oily organelles extremely abundant in oil storing seeds. These organelles, termed oil bodies, are easily isolated from other cellular components by flotation-centrifugation. Hence, exploiting the targeting of foreign proteins to oil bodies through oleosin-fusion is an efficient means to enhance accumulation and purification efficiency from seeds. So far, several pharmaceuticals have been produced and efficiently purified from plants through this technology.
In this work a further application for oil bodies has been envisaged. In particular, owing to the corpusculate nature and lipid components, oil bodies have been considered as possible carriers of immunologically-active peptides (epitopes) for novel vaccine formulations. For this purpose, Arabidopsis thaliana plants have been engineered to express sequences derived from Human Immunodeficiency Virus type 1 (HIV-1) and influenza virus as fusions to 19K sunflower oleosin. Transgenic plants have been genetically characterized and oil bodies purified from transgenic seeds. Both wild type and chimeric oil bodies have been analysed by Mass Spectrometry approach either to reveal the whole composition of oil body associated proteins with the aim to fine characterize the vaccine carrier and to confirm the presence of the HIV-1- and influenza virus-derived epitopes in sunflower oleosin fusions. The immunological properties of the chimeric oil bodies have been evaluated in vivo by appropriate murine model. The ability to elicit cellular immune responses, that is crucial to protect against viral pathogens such as HIV-1 and influenza, has been demonstrated. Despite adjuvant properties has not been evidenced so far, preliminary results suggest that further investigation is necessary.
In conclusion, the oil body-derived platform suggested in the present PhD thesis demonstrates the full applicability of this technology for plant-derived vaccines.
Additional information
Dottorato di ricerca in Biotecnologie vegetali
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