A Plant-Produced Pfs25 VLP Malaria Vaccine Candidate Induces Persistent Transmission Blocking Antibodies against Plasmodium falciparum in Immunized Mice

Abstract

Malaria transmission blocking vaccines (TBVs) are considered an effective means to control and eventually eliminate malaria. The Pfs25 protein, expressed predominantly on the surface of the sexual and sporogonic stages of Plasmodium falciparum including gametes, zygotes and ookinetes, is one of the primary targets for TBV. It has been demonstrated that plants are an effective, highly scalable system for the production of recombinant proteins, including virus-like particles (VLPs). We engineered VLPs (Pfs25-CP VLP) comprising Pfs25 fused to the Alfalfa mosaic virus coat protein (CP) and produced these non-enveloped hybrid VLPs in Nicotiana benthamiana plants using a Tobacco mosaic virus-based ‘launch’ vector. Purified Pfs25-CP VLPs were highly consistent in size (19.3±2.4 nm in diameter) with an estimated 20–30% incorporation of Pfs25 onto the VLP surface. Immunization of mice with one or two doses of Pfs25-CP VLPs plus Alhydrogel® induced serum antibodies with complete transmission blocking activity through the 6 month study period. These results support the evaluation of Pfs25-CP VLP as a potential TBV candidate and the feasibility of the ‘launch’ vector technology for the production of VLP-based recombinant vaccines against infectious diseases.

Alga-Produced Malaria Transmission-Blocking Vaccine Candidate Pfs25 Formulated with a Human Use-Compatible Potent Adjuvant Induces High-Affinity Antibodies That Block Plasmodium falciparum Infection of Mosquitoes

“…Sig, significant. observed with another plant-based method with hydroponic Nicotiana (14,39). Microalgae and single-celled waterborne plants grow much more rapidly than more complex plants and can be cultured under cyclic GMP (cGMP) conditions at low cost (50).…”

“…Parasite-produced Pfs25 contains 4 epidermal growth factor (EGF)-like domains and is not glycosylated, which makes it biotechnologically challenging to produce the properly folded, conformationally correct recombinant protein(s) required for the induction of effective transmission-blocking antibodies (7)(8)(9). Heterologous expression systems used to produce Pfs25 as a recombinant subunit immunogen include Escherichia coli (10), Saccharomyces cerevisiae (11), Pichia pastoris (7,12), baculovirus (13), Nicotiana benthamiana (14), Triticum vulgare (wheat germ) extract (6,15,16), and most recently, the chloroplast of the microalga Chlamydomonas reinhardtii (17,18).…”

Recent Developments in Malaria Vaccinology

“…Clinical testing of Pfs25-EPA in humans has now been initiated in the US and Mali. Another approach in which Pfs25 was fused to Alfalfa mosaic virus coat protein also showed promising results in mice (Jones et al, 2013) and is currently being assessed in a Phase Ia dose escalation study, the results of which are awaited. Furthermore, recombinant replication-deficient viral vectors in prime-boost regimes have also been explored as a TBV platform.…”

7. Themenbereich grüne Gentechnologie: Pflanzenzüchtung und Agrarwirtschaft

“…Für eine Vielzahl verschiedener Krankheiten wie Gebärmutterhalskrebs, Tuberkulose, Hepatits B, Cholera, HIV sowie Durchfallerkrankungen und viele weitere werden weltweit PMPs entwickelt. 80 Die Gewinnung von humanem Serum Albumin (HSA) aus Reis ist chinesischen Forschern gelungen (He et al, 2011 Clemente/Corigliano, 2012;Waheed et al, 2012;Ahmad et al, 2012;Yusibov et al, 2011. setzt wurde und Wirksamkeit gegenüber dem Malaria-Erreger Plasmodium falciparum zeigte (Jones et al, 2013). Eine umfangreiche Darstellung bisheriger Arbeiten zur Produktion von Vakzinen in transgenen Pflanzen findet sich in Guan et al (2013).…”