A highly infectious Plasmodium yoelii parasite, bearing Plasmodium falciparum circumsporozoite protein.

Min Zhang,Moriya Tsuji,Shiroh Iwanaga,Robert Mitchell,Elizabeth H Nardin,Tiffany Tsao,Masao Yuda,Izumi Kaneko

doi:10.1186/s12936-016-1248-z

Abstract

BackgroundPlasmodium circumsporozoite protein (CSP) is a major surface antigen present in the sporozoite (Spz) stage of a malaria parasite. RTS, S vaccine, the most clinically advanced malaria vaccine, consists of a large portion of Plasmodium falciparum CSP (PfCSP). A highly infectious, recombinant rodent malaria, Plasmodium yoelii parasite bearing a full-length PfCSP, PfCSP/Py Spz, was needed as a tool to evaluate the role of PfCSP in mediating, protective, anti-malaria immunity in a mouse model.MethodsA transgenic parasite, PfCSP/Py Spz, was generated by inserting a construct expressing the PfCSP at the locus of the P. yoelii CSP gene by double cross-over homologous recombination. Then the biological and protective properties of PfCSP/Py Spz were determined.ResultsThis PfCSP/Py parasite produced up to 30,000 Spz in mosquito salivary glands, which is equal or even higher than the number of Spz produced by wild-type P. yoelii parasites. Five bites of PfCSP/Py-infected mosquitoes could induce blood infection in BALB/c mice.ConclusionsThe current study has demonstrated a successful establishment of a transgenic P. yoelii parasite clone that is able to express a full-length PfCSP, PfCSP/Py parasite. Importantly, this PfCSP/Py parasite can be as infectious as the wild-type P. yoelii parasite both in mosquito vector and in mouse, a mammalian host. A new transgenic parasite that expresses a full-length PfCSP may become a useful tool for researchers to investigate immunity against PfCSP in a mouse model.

Highlights

Plasmodium circumsporozoite protein (CSP) is a major surface antigen present in the sporozoite (Spz) stage of a malaria parasite
Biological properties of Plasmodium falciparum CSP (PfCSP)/Py parasites A hybrid P. yoelii parasite has been generated by replacing full P. yoelii CSP (PyCSP) with full PfCSP via double cross-over recombination
The hybrid PfCSP/Py Spz were recognized by 2A10 monoclonal antibody (mAb), an antibody that reacts with the central repeats of the PfCSP [27]

Summary

Introduction

Plasmodium circumsporozoite protein (CSP) is a major surface antigen present in the sporozoite (Spz) stage of a malaria parasite. PfPb parasites were used to investigate the in vivo protection induced by the anti-PfCSP monoclonal antibodies (mAbs) delivered by adeno-associated, virus-based gene transfer [17]. The lack of both N-terminal and C-terminal in the PfPb parasite is a drawback for its use in the analysis of protective immunity mediated by T-cells as the non-repeat regions contain the majority of the CD4+ and CD8+ T cell epitopes of PfCSP [18,19,20]. A recombinant P. berghei parasite expressing a full-length PfCSP was generated, but the parasite’s infectivity was very low in the mosquito salivary gland [21, 22]

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