Fine structure of the malaria parasite Plasmodium falciparum in human hepatocytes in vitro

Meis, Jacques F.; Rijntjes, P. J. M.; Verhave, J.P.; Ponnudurai, T.; Hollingdale, Michael R.; Smith, Judith E.; Sinden, Robert E.; Jap, P. H. K.; Meuwissen, J. H. E. T.; Yap, Sing Hiem

doi:10.1007/bf00219210

Cited by 31 publications

(13 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed, few of numerous hepatoma cell lines permit the development of the intrahepatic phase of P. falciparum [53,54], and, thus far, none has proved able to sustain satisfactorily the complete development of the parasite. In contrast, human hepatocytes transplanted into treated uPA-SCID mice were sufficiently well differentiated to sustain the development of liver schizonts; their size, reaching 50-60 mm 5 days after inoculation with sporozoites, was as large as that which has been observed in either humans [33] or chimpanzees [6,34] and was twice as large as that which has been observed in primary human-hepatocyte cultures in vitro [55,56]. Furthermore, their development was very homogeneous among the liver schizonts.…”

Section: Discussionmentioning

confidence: 51%

Liver‐Stage Development ofPlasmodium falciparum,in a Humanized Mouse Model

et al. 2006

View full text Add to dashboard Cite

show abstract

Section: Discussionmentioning

confidence: 51%

Liver‐Stage Development ofPlasmodium falciparum,in a Humanized Mouse Model

et al. 2006

View full text Add to dashboard Cite

show abstract

“…The reported sizes of late P. falciparum LSs obtained from in vitro culture range from only 15 to 40 μm in diameter (6,7,39,40), whereas we visualized LS sizes up to 80 μm in diameter, which, based on previous volume calculations (29), contain between 40,000 and 60,000 merozoites. A small number of studies on P. falciparum LS development in humans have been undertaken (41,42), and the size of 6 day LS ranged from 55 to 60 μm.…”

Section: Frg Huhep and Frg Nod Huhep Micementioning

confidence: 45%

Complete Plasmodium falciparum liver-stage development in liver-chimeric mice

et al. 2012

View full text Add to dashboard Cite

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. IntroductionPlasmodium falciparum is the most deadly of the human malaria parasites. The disease continues to be a global health crisis and causes more than 250 million new clinical cases annually, resulting in over 800,000 deaths, mostly of children in sub-Saharan Africa (1). Female anopheline mosquitoes introduce infectious sporozoites into the host dermis when taking a blood meal. Sporozoites exit the bite site by migration, enter a blood vessel, and are carried to the liver (2). Here, each sporozoite traverses numerous hepatocytes before it invades a final hepatocyte with the formation of a parasitophorous vacuole (PV) (3). Ensconced in the PV, the parasite undergoes liver-stage (LS, also called exoerythrocytic form [EEF]) development, culminating in the formation and release of tens of thousands of first generation merozoites (4). This preerythrocytic phase of the parasite life cycle is asymptomatic, and all clinical pathologies are caused by the ensuing asexual erythrocytic stage of infection. The erythrocytic stages are routinely studied in vitro, made possible by the development of a continuous culture system that allows asexual parasite replication in human rbc (hurbc) (5). However, studying the biology and pathophysiology of P. falciparum in vivo is difficult and is hampered by the lack of adequate animal models. Sporogonic stages are generated by feeding female Anopheles mosquitoes on in vitro gametocyte cultures, allowing progression of the parasite life cycle in the mosquito and subsequent sporozoite accumulation...

show abstract

“…Of interest is the finding that a peptide form the LSA-1 N-terminal region binds to hepatic cells and to HLA-DRβ1*1101[20], which is consistent with the induction of CD4 + T cell responses in clinical trials[11,21]. Analysis of infected primate liver sections probed with antibodies against LSA-1 has shown that synthesis of LSA-1 begins soon after sporozoite invasion and that the protein accumulates throughout the liver stage development [22,23]. From three days post infection, LSA-1 is detectable in the parasitophorous vacuole (PV), which is delineated by the inner plasmalemma and the outer parasitophorous vacuole membrane (PVM) of the infected hepatocyte, and surrounds the developing merozoites as part of a "flocculent mass" [23].…”

Section: Introductionmentioning

confidence: 71%

Plasmodium falciparum liver stage antigen-1 is cross-linked by tissue transglutaminase

Nicoll

Sacci

Rodolfo

et al. 2011

Malar J

View full text Add to dashboard Cite

BackgroundPlasmodium falciparum sporozoites injected by mosquitoes into the blood rapidly enter liver hepatocytes and undergo pre-erythrocytic developmental schizogony forming tens of thousands of merozoites per hepatocyte. Shortly after hepatocyte invasion, the parasite starts to produce Liver Stage Antigen-1 (LSA-1), which accumulates within the parasitophorous vacuole surrounding the mass of developing merozoites. The LSA-1 protein has been described as a flocculent mass, but its role in parasite development has not been determined.MethodsRecombinant N-terminal, C-terminal or a construct containing both the N- and C- terminal regions flanking two 17 amino acid residue central repeat sequences (LSA-NRC) were subjected to in vitro modification by tissue transglutaminase-2 (TG2) to determine if cross-linking occurred. In addition, tissue sections of P. falciparum-infected human hepatocytes were probed with monoclonal antibodies to the isopeptide ε-(γ-glutamyl)lysine cross-bridge formed by TG2 enzymatic activity to determine if these antibodies co-localized with antibodies to LSA-1 in the growing liver schizonts.ResultsThis study identified a substrate motif for (TG2) and a putative casein kinase 2 phosphorylation site within the central repeat region of LSA-1. The function of TG2 is the post-translational modification of proteins by the formation of a unique isopeptide ε-(γ-glutamyl)lysine cross-bridge between glutamine and lysine residues. When recombinant LSA-1 protein was crosslinked in vitro by purified TG2 in a calcium dependent reaction, a flocculent mass of protein was formed that was highly resistant to degradation. The cross-linking was not detectably affected by phosphorylation with plasmodial CK2 in vitro. Monoclonal antibodies specific to the very unique TG2 catalyzed ε- lysine cross-bridge co-localized with antibodies to LSA-1 in infected human hepatocytes providing visual evidence that LSA-1 was cross-linked in vivo.ConclusionsWhile the role of LSA-1 is still unknown these results suggest that it becomes highly cross-linked which may aid in the protection of the parasite as it develops.

show abstract

Fine structure of the malaria parasite Plasmodium falciparum in human hepatocytes in vitro

Cited by 31 publications

References 29 publications

Liver‐Stage Development ofPlasmodium falciparum,in a Humanized Mouse Model

Liver‐Stage Development ofPlasmodium falciparum,in a Humanized Mouse Model

Complete Plasmodium falciparum liver-stage development in liver-chimeric mice

Plasmodium falciparum liver stage antigen-1 is cross-linked by tissue transglutaminase

Contact Info

Product

Resources

About