Complete Plasmodium falciparum liver stage development in liver-chimeric mice

The Journal of clinical investigation (Impact Factor: 13.22). 09/2012; 122(10):3618-28. DOI: 10.1172/JCI62684
Source: PubMed


Plasmodium falciparum, which causes the most lethal form of human malaria, replicates in the host liver during the initial stage of infection. However, in vivo malaria liver-stage (LS) studies in humans are virtually impossible, and in vitro models of LS development do not reconstitute relevant parasite growth conditions. To overcome these obstacles, we have adopted a robust mouse model for the study of P. falciparum LS in vivo: the immunocompromised and fumarylacetoacetate hydrolase-deficient mouse (Fah-/-, Rag2-/-, Il2rg-/-, termed the FRG mouse) engrafted with human hepatocytes (FRG huHep). FRG huHep mice supported vigorous, quantifiable P. falciparum LS development that culminated in complete maturation of LS at approximately 7 days after infection, providing a relevant model for LS development in humans. The infections allowed observations of previously unknown expression of proteins in LS, including P. falciparum translocon of exported proteins 150 (PTEX150) and exported protein-2 (EXP-2), components of a known parasite protein export machinery. LS schizonts exhibited exoerythrocytic merozoite formation and merosome release. Furthermore, FRG mice backcrossed to the NOD background and repopulated with huHeps and human red blood cells supported reproducible transition from LS infection to blood-stage infection. Thus, these mice constitute reliable models to study human LS directly in vivo and demonstrate utility for studies of LS-to-blood-stage transition of a human malaria parasite.

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Available from: Ashley M Vaughan, Dec 18, 2013
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    • "Replacement indices of N 90% can be achieved (Azuma et al., 2007; Hasegawa et al., 2011; Hu et al., 2013; Dandri et al., 2001; Tateno et al., 2004). Liver chimeric mice have been used to study infections (Dandri et al., 2001; Bissig et al., 2010; Mercer et al., 2001; Morosan et al., 2006; Vaughan et al., 2012; Kawahara et al., 2013), drug metabolism (Tanoue et al., 2013; Sanoh et al., 2012), gene therapy (Lisowski et al., 2014) and hepatic stem cells (Duncan et al., 2012; Takebe et al., 2013; Zhu et al., 2014). Importantly however, many normal and pathophysiologic processes in the liver involve interactions between blood derived cells and hepatic epithelial cells. "
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    • "Salivary gland dissections were performed at days 14–19. Production of P. falciparum sporozoites and the infection of FRG KO huHep mice with P. falciparum were performed as previously described (Vaughan et al., 2012). "
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    ABSTRACT: Plasmodium vivax malaria is characterized by periodic relapses of symptomatic blood stage parasite infections likely initiated by activation of dormant liver stage parasites-hypnozoites. The lack of tractable P. vivax animal models constitutes an obstacle in examining P. vivax liver stage infection and drug efficacy. To overcome this obstacle, we have used human liver-chimeric (huHep) FRG KO mice as a model for P. vivax infection. FRG KO huHep mice support P. vivax sporozoite infection, liver stage development, and hypnozoite formation. We show complete P. vivax liver stage development, including maturation into infectious exo-erythrocytic merozoites as well as the formation and persistence of hypnozoites. Prophylaxis or treatment with the antimalarial primaquine can prevent and eliminate liver stage infection, respectively. Thus, P. vivax-infected FRG KO huHep mice are a model to investigate liver stage development and dormancy and may facilitate the discovery of drugs targeting relapsing malaria. Copyright © 2015 Elsevier Inc. All rights reserved.
    Cell host & microbe 03/2015; 17(4). DOI:10.1016/j.chom.2015.02.011 · 12.33 Impact Factor
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    • "The recent reports of luciferase-expressing parasites of different species, including P. yoelii[12] as well as Plasmodium falciparum[13], will allow the expansion of this protocol to these species. Most importantly, the description of liver and blood-humanized mice (until now still in separate hosts) [14,15] may soon allow the establishment of this assay to test different strategies against P. falciparum infection. As such, the use of different luciferase-expressing parasites may greatly accelerate and streamline the process of identifying and analysing future vaccine candidates as well as drug candidates against the pre-erythrocytic stages of malaria parasites, including those that may target the parasite at very late states or transition period between stages. "
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    ABSTRACT: The first phase of malaria infection occurs in the liver and is clinically silent. Inside hepatocytes each Plasmodium sporozoite replicate into thousands of erythrocyte-infectious merozoites that when released into the blood stream result in clinical symptoms of the disease. The time between sporozoite inoculation and the appearance of parasites in the blood is defined as the pre-patent period, which is classically analysed by time-consuming and labor-intensive techniques, such as microscopy and PCR. Luciferase-expressing Plasmodium berghei parasites were used to measure pre-patent period of malaria infection in rodents using a bioluminescence assay that requires only one microliter of blood collected from the tail-vein. The accuracy and sensitivity of this new method was compared with conventional microscopy and PCR based techniques, and its capacity to measure the impact of anti-malarial interventions against the liver evaluated. The described method is very sensitive allowing the detection of parasites during the first cycles of blood stage replication. It accurately translates differences in liver load due to inoculation of different sporozoite doses as well as a result of treatment with different primaquine regimens. A novel, simple, fast, and sensitive method to measure pre-patent period of malaria infection in rodents is described here. The sensitivity and accuracy of this new method is comparable to standard PCR and microscopy-based techniques, respectively.
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