Gene Disruption of p52 of the human parasite P. falciparum results in attenuation of malaria liver stage development: implications for vaccine development
Researchers from Leiden (LUMC) and Nijmegen have characterized a large number of parasite proteins that may prove useful in the development of a human malaria vaccine (published in PLoS Pathogens).Collaborators had previously shown how to successfully vaccinate mice using a rodent malaria which had one of these liver stage genes removed, specifically p36p. In a related article, published October 28th in PLoS ONE, the researchers show the first transition of such a vaccination from the rodent system to humans, by inactivating the equivalent gene (p52) in the major human malaria parasite, P. falciparum. Similar to the results with the rodent parasite, these human parasites are unable to develop in liver cells. This is the first time that genetic modification of a human parasite results in its growth arrest in a liver cell, opening up promising possibilities for its use as a human vaccine. These studies show how results obtained in rodent models of malaria can be pipelined to form the basis for clinical development of antimalaria vaccines in humans.
To better manage the Leiden Malaria Research Groups P. berghei protocols and reference databases this information has been placed in a 'SharePoint' environment (groepen-forms.lumc.nl/sites/leidenmalaria/default.aspx)
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In case you do not have an institutional e-mail address you have to find the methods in our published papers (see PubMed; we do not send papers to other groups/researchers).
Update of the website of the Leiden Malaria Research Group, with special emphasis on the password protected area
Additional and/or new information, explanations and information updates on the website; based on questions we have received in the last two years from ‘researchers in the field’:Protocols:
In addition to the ‘general laboratory protocols’, three protocols which we published in Nature Protocols on transfection and in-vivo imaging are available on the website including the videos showing purification of schizonts and transfection.Transgenic P. berghei parasite lines
We have deposited at MR4 a number of our transgenic P. berghei lines expressing reporters such as GFP and Luciferase as well as transgenic lines that are deficient in expressing specific parasite proteins. Since these lines can now be obtained from MR4, we do not send any of these lines directly to other laboratories. We have provided additional information on our website about the lines that are present at MR4, in combination with their MRA-number. For obtaining other P. berghei lines (i.e. those not deposited with MR4) from our laboratory, we request you to fill out the parasite request form on this website.Plasmids:
A collection of standard plasmids have been deposited at MR4. Details of these plasmids (e.g. sequence, plasmid map, integration locus, selectable marker cassette etc) can be found in an Excel sheet on our website. Two plasmids are now available that contain the drug-selection cassette, hDHFR and yFCU, as a fusion gene for both positive and negative selection procedures (MRA-849 = pl0034, MRA-850 = pl0035).Databases:
In addition to the transcriptome and proteome data of blood stages and gametocytes of P. berghei, data is provided on the chromosome location and synteny of genes of the rodent malaria parasites (in comparison with P. falciparum). Biosafety issues of working with transgenic P. berghei: Information is provided about biosafety levels and health (monitoring) reports for mice infected with P. berghei lines.
Translational repression in gametes and zygotes of malaria parasites: new insights from the Leiden Malaria Group
Translational repression (TR) during sexual development appears to be an ancient process for controlling the timing of expression of proteins. Unicellular eukaryotes of the genus Plasmodium use TR to regulate protein expression during gamete and zygote formation. Previously we have identified a Plasmodium protein (DDX6-class RNA helicase) involved in TR and which forms a complex with repressed mRNA's (Mair et al., 2006, Science 313:667-9). In a recent paper we now report the involvement in TR of specific regions/domains in the 3’- and 5’-UTR’s of the repressed mRNA transcripts. These results demonstrate that TR in Plasmodium is mediated by both cis- and trans-acting factors that are closely analogous to those employed in TR of higher eukaryotes (Braks et al., (2007). A conserved U-rich RNA region implicated in regulation of translation in Plasmodium female gametocytes. Nucleic Acids Research 2007, 1-11 (23 December).
A number of P. berghei transgenic/mutant lines generated in the Leiden Malaria Group are now available from Malaria Research and Reference Reagent Resource Center, MR4
See the following links:
The Plasmodium homologue of Macrophage Migration Inhibitory factor (MIF) has been characterized in the Leiden Malaria Group:
MIF is an important regulator of inflammatory response in mammalians. MIF is an unusually versatile chemokine/cytokine in that it is involved in both pro- and anti-inflammatory response and cellular proliferation. In malaria infections host MIF response has been shown to correlate with disease severity and anemia. Surprisingly, analysis of the Plasmodium genome revealed the presence of a single MIF homologue. Since these parasites themselves do not have an immune system, we hypothesized that Plasmodium might produce a MIF homologue to interfere with the host immune response. In order to test this hypothesis, we undertook a functional characterization of the Plasmodium homologue of MIF using purified recombinant protein and genetic manipulation of P. berghei parasites. (Augustijn KD et al., (2007) Functional characterization of the Plasmodium falciparum and P. berghei homologues of macrophage migration inhibitory factor. Infect. Immun. 75:1116-28.