| Successful modification | The parasite was generated by the genetic modification |
| The mutant contains the following genetic modification(s) |
Gene disruption,
Introduction of a transgene
|
| Reference (PubMed-PMID number) |
Reference 1 (PMID number) : 25329441
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| MR4 number |
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| Parent parasite used to introduce the genetic modification |
| Rodent Malaria Parasite | P. berghei |
| Parent strain/line | P. berghei ANKA |
| Name parent line/clone |
P. berghei ANKA 507cl1 (RMgm-7)
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| Other information parent line | P.berghei ANKA 507cl1 (RMgm-7) is a reference ANKA mutant line which expresses GFP under control of a constitutive promoter. This reference line does not contain a drug-selectable marker (PubMed: PMID: 16242190). |
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| The mutant parasite was generated by |
| Name PI/Researcher | Mathieu, C; Menard, R; Mecheri, S |
| Name Group/Department | Unité de Biologie des Interactions Hôte Parasites |
| Name Institute | Institut Pasteur |
| City | Paris |
| Country | France |
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| Name of the mutant parasite |
| RMgm number | RMgm-1135 |
| Principal name | HRFΔ1-3 |
| Alternative name | |
| Standardized name | |
| Is the mutant parasite cloned after genetic modification | Yes |
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| Phenotype |
| Asexual blood stage | Not different from wild type |
| Gametocyte/Gamete | Not different from wild type |
| Fertilization and ookinete | Not different from wild type |
| Oocyst | Not different from wild type |
| Sporozoite | Not different from wild type |
| Liver stage | Sporozoites did not display any detectable defect in gliding motility, host cell traversal or host cell invasion of HepG2 cells.
HRFΔ1 and WT developed indistinguishably inside HepG2 cells into exo-erythrocytic forms (EEF, liver stages). Therefore, HRF does not appear to be important for a basic parasite developmental step detectable in vitro.
To test pre-erythrocytic stage infectivity, sporozoites were inoculated into mice by mosquito bite, intradermal or intravenous injection and emergence of blood-stage parasites monitored by FACS. Only 40 to 50% of animals became infected after injection of HRFΔ1 sporozoites when 100% animals were infected after injection of WT parasites. Animals became patent with HRFΔ1 blood-stage parasites on average 2 to 3 days after the WT following infection by mosquito bites or inoculation of isolated sporozoites, corresponding to a 100 to 1000-fold decrease in infectivity of mutant parasites. |
| Additional remarks phenotype | Mutant/mutation
The mutant lacks expression of HRF/TCTP and expresses GFP under the constitutive eef1a promoter.
Protein (function)
Histamine releasing factor (HRF), originally classified as a tumor protein (translationally controlled tumor protein, TCTP) in mouse erythroleukemia, is found in a wide range of eukaryotes including yeast, plants and animals. The name TCTP was coined as a consequence of cDNA cloning from a human mammary carcinoma and based on the fact that TCTP is regulated at the translational level. HRF plays many different functions and is involved in many physiological processes such as cell proliferation, stress and heat shock responses, and cell death. As an intracellular product, HRF has a calcium and tubulin binding properties and has been shown to transiently associate with microtubules during cell cycle. As a calcium-binding protein HRF was found to be up-regulated in response to a loss of calcium homeostasis which could be part of a role of HRF in general stress response.
As a secreted product, HRF has immuno-modulatory roles. In humans, HRF induces the release of histamine and modulates cytokine secretion from basophils, eosinophils, and T cells. HRF stimulates eosinophils to produce IL-8, induces secretion of IL-4 and IL-13 from basophils and inhibits IL-2, IL-4, and IL-13 production from stimulated primary T cells (Vonakis et al., 2003). Recently, HRF was found to have an inflammatory role in mouse models of asthma and allergy and to exist as a dimer bound to a subset of IgE and IgG antibodies, suggesting the possibility for HRF to cross-link IgE on the surface of basophils and mast cells.
HRF is also expressed by a number of eukaryotic parasites, including Plasmodium.
Plasmodium HRF, which has a high homology to human HRF (their amino acid sequences are 33% identical and 54% similar) has been proposed to play an important role during the erythrocytic phase of malarial infection (MacDonald et al., 2001).
Phenotype
Phenotype analyses indicate that the absence of HRF does not influence blood stage growth/multiplication and experimental cerebral complications (ECM in C57Bl6 mice).The absence of HRF appears not to affect sporozoite production, motility and infectivity and development of liver stages in vitro.
Evidence is presented that.the absence of HRF results in lower (~2,5x) parasite liver loads in vivo (see also 'Additional Information' below).
Additional information
Evidence is presented for HRF expression in liver stages (using anti-HRF antibodies).
Evidence is presented that the lack of HRF increases IL-6 production in the infected liver.
Evidence is presented that the lack of HRF impact on host (immune) cell recruitment in the infected liver.
Based on these observations it is concluded 'parasite HRF is thus used to down-regulate a cytokine (IL-6) with anti-parasite activity'.
Other mutants |
*RMgm-1135
