Heat‐precipitation allows the efficient purification of a functional plant‐derived malaria transmission‐blocking vaccine candidate fusion protein

Abstract

Malaria is a vector-borne disease affecting more than two million people and accounting for more than 600,000 deaths each year, especially in developing countries. The most serious form of malaria is caused by Plasmodium falciparum. The complex life cycle of this parasite, involving pre-erythrocytic, asexual and sexual stages, makes vaccine development cumbersome but also offers a broad spectrum of vaccine candidates targeting exactly those stages. Vaccines targeting the sexual stage of P. falciparum are called transmission-blocking vaccines (TBVs). They do not confer protection for the vaccinated individual but aim to reduce or prevent the transmission of the parasite within a population and are therefore regarded as an essential tool in the fight against the disease. Malaria predominantly affects large populations in developing countries, so TBVs need to be produced in large quantities at low cost. Combining the advantages of eukaryotic expression with a virtually unlimited upscaling potential and a good product safety profile, plant-based expression systems represent a suitable alternative for the production of TBVs. We report here the high level (300 μg/g fresh leaf weight (FLW)) transient expression in Nicotiana benthamiana leaves of an effective TBV candidate based on a fusion protein F0 comprising Pfs25 and the C0-domain of Pfs230, and the implementation of a simple and cost-effective heat treatment step for purification that yields intact recombinant protein at >90% purity with a recovery rate of >70%. The immunization of mice clearly showed that antibodies raised against plant-derived F0 completely blocked the formation of oocysts in a malaria transmission-blocking assay (TBA) making F0 an interesting TBV candidate or a component of a multi-stage malaria vaccine cocktail.

ThePlasmodium falciparumblood stages acquire factor H family proteins to evade destruction by human complement

“…In accordance with our observations that the ACP is as a major threat for the malaria parasites in the mosquito midgut, transmission blocking antibodies against prominent sexual stage surface proteins like Pfs230 or Pfs25 require active human complement to kill the mosquito midgut stages, as was previously shown in standard membrane feeding assays (e.g. Read et al, 1994;Williamson et al, 1995;Healer et al, 1997;Beiss et al, 2015;Boes et al, 2015;reviewed in Pradel, 2007). Furthermore, in the presence of anti-Pfs230 antibodies complement factor C1q binds to the gamete surface and activates the classical complement pathway (Simon et al, 2013).…”

“…Read et al , 1994; Williamson et al , 1995; Healer et al , 1997; Beiss et al , 2015; Boes et al , 2015; reviewed in Pradel, 2007). Furthermore, in the presence of anti‐Pfs230 antibodies complement factor C1q binds to the gamete surface and activates the classical complement pathway (Simon et al , 2013).…”

Strategies & recent development of transmission-blocking vaccines against Plasmodium falciparum

“…The plant-based expression system provides all the advantages of a eukaryotic expression system with high purity and stability. Various TBV candidates have been successfully produced in plant system707172 with high recovery and desired immunogenicity (Table IV). Algae are also a promising system for the production of TBV that are orally delivered to avoid expensive purification and injectible delivery737475.…”

Expression optimization of a cell membrane-penetrating human papillomavirus type 16 therapeutic vaccine candidate in Nicotiana benthamiana

“…Furthermore, plant production is highly scalable, from laboratory benchtops through to agricultural scale in fields, greenhouses or in vertical farming units [ 22 – 25 ]. Plants have also been shown to produce biologically functional pharmaceuticals, including products presently in use in humans such as glucocerebrocidase [ 22 , 26 – 29 ].…”