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  Director : BREY Paul (pbrey@pasteur.fr)


  abstract

 

Our research unit is working on three tightly linked subjects : 1) Anopheles genomics and post-genomics : 2) host-parasite interactions between malaria parasites and mosquito vectors especially during the early phases of the sporogonic cycle, 3) Dipteran innate immune response with special focus on the regulation of the melanization cascade and signal transduction pathways involved in immune response. Our aim is to better understand the natural history and interactions of the malaria parasite within its invertebrate host with the hope of finding ways to interrupt or regulate this interaction.



  report

cale

Genomics of A. gambiae (Charles Roth, Martine Grailles, Inge Holm and Paul Brey)

The Institut Pasteur is a member of the international consortium that successfully sequenced the genome of this important Plasmodium vector. The sequence of the genome and the preliminary analysis of the genes was completed in 2002 (Science. 2002 Oct 4;298(5591):129-49.). The 278 million base pair sequence covering about 90% of the genome was predicted to contain nearly 14 thousand genes. Our unit is working to increase the accuracy of the genomic sequences and the identification of the proteins it encodes. These studies are will allow us to prediction which proteins might interact with each other or with the malaria parasite and be targets for blocking parasite infections. We are also studying membrane transporters in the mosquito that resemble those used by human cancer cells to evade the killing effects of anit-tumor drugs. These studies could lead to drugs that make anti-tumor drugs and insecticides more effective.

Proteomics approach of A. gambiae saliva and salivary glands (Valérie Choumet, Virginie Jan and Paul Brey)

Our team will carry out a structural and functional proteomics approach of Anopheles gambiae saliva and salivary glands. On one hand, there is now compelling evidence that the pharmacological activity of arthropod saliva has a profound effect on pathogen transmission. The study of its composition could then provide new vaccine targets in the prevention and the treatment of malaria. On the other hand, the saliva of blood-sucking insects is known to contain a large variety of peptides and proteins whose great specificity of action makes them powerful pharmacological tools to dissect certain physiological mechanisms and to propose new drugs or diagnostic tests. The structural proteomics analysis, carried out in collaboration with the platform "Protéomique" of the Pasteur Institute. With regard to the functional proteomics approach, our team will more particularly focus her efforts on the characterization of anti-hemostatic and proinflammatory components.

Alterations of A. gambiae salivary gland transcriptome during infection by Plasmodium (Isabelle Rosinski-Chupin, Sylvie Perrot, Massimiliano Veneri and Paul Brey).

For the successful completion of the life cycle in mosquitoes, the parasites must migrate through the salivary gland epithelial barrier. Our work hypothesis is that the presence of the parasite inside or in close contact with the salivary gland cells will induce cellular defense mechanism, and a change in gene expression. This change might in turn have some role in the survival of the parasite, and therefore, in the transmission of the disease. Recent sequencing of the Anopheles genome will enable us to analyze these changes in gene expression on a global level, and we are currently developing two techniques for characterization of salivary gland transcriptome: the SAGE technique (Serial analysis of gene expression) and the microarrays. This work is part of the Anopheles "Grand Projet Horizontal" at the Pasteur Institute.

Gene discovery in Plasmodium- host cell interactions during the sporogonic cycle (Anna Raibaud, Karima Brahimi, Richard Paul and Paul Brey)

Currently, our studies are part of a transversal research program in collaboration with two other laboratories within the Pasteur Institute (Unité Postulante de Biologie et Génétique du Paludisme et Unité Génétique de la Différentiation). The object of the program we propose is to identify and functionally characterise novel genes which are expressed by the two sporogonic invasive stages (the ookinete and the sporozoite) and the hepatocyte. We will apply a recently developed gene discovery approach, suppression subtractive hybridisation (SSH) and use the P. berghei system, whose entire life cycle can be achieved in the laboratory, for which the infection of hepatocytes can go to completion in vitro and which is the model of choice for molecular studies because of the relative ease of targeted mutagenesis. In this way we aim to identify novel therapeutic targets.

Evolutionary ecology of Plasmodium and virulence-transmission interactions according to infection complexity (Richard Paul and Paul Brey)

The population structure of parasitic organisms determines the degree of parasite inbreeding, which has important epidemiological consequences and is a strong determinant in the evolution of virulence. Virulence is, however, a complex phenotype; parasite sex ratio is predicted to be highly informative for how virulence might evolve in natural populations as both are predicted to respond in the same way to population structure and can thus be modelled similarly. Anaemia is the major form of virulence in malaria and the host haematological state is correlated with parasite sex allocation: reticulocyte density positively correlates with gametocyte density and in animal models of malaria, erythropoietin was implicated in gametocyte sex determination (Paul et al. 2000). Thus anaemia is a physical manifestation of virulence and an indirect trigger of sex allocation. Establishing how infection genetic diversity relates to anaemia has not only considerable importance for disease management but also for influencing parasite transmission phenotypes.

Biochemical and genetic characterization of Serpin-27A (spn27A, CG11331) in Drosophila melanogaster (Sung Jun Han and Paul Brey)

The identification of genes that regulate the melanization cascade in Drosophila has been complicated by the high number of serpin and serine protease candidate genes in the fly genome. Recently, a DNA microarray analysis helped us to select 5 serpin genes among the 30 encoded by the Drosophila genome that, like spn43Ac, are significantly up-regulated in response to infection and might control one of the serine protease cascades associated to fly immune reactions. Our data demonstrate that Spn27A regulates the melanization cascade through the specific inhibition of PPO processing by the terminal serine protease PPAE.

Characterization of the serpin-27A homologue in A. gambiae (Isabelle Rosinski-Chupin, Sylvie Perrot and P. Brey)

Melanotic encapsulation of Plasmodium in some refractory strains of Anopheles results in a block to parasite transmission. For this reason, we are interested in the regulation of the melanisation cascade in A. gambiae, especially in the regulation of phenoloxydase activity, where prophenoloxydase is the key enzyme in the melanisation response. We have identified in sequence databases two homologues of the Drosophila Serpin 27A, which are predicted to modulate phenoloxydase activity in mosquito. The corresponding genes were cloned and characterization of the biological function of these serpins is in progress.

Keywords: Mosquito, insect, vector, Drosophila, immune response, parasites, genomics, Anopheles gambiae, Plasmodium



  publications

puce Publications of the unit on Pasteur's references database


  personnel

  Office staff Researchers Scientific trainees Other personnel
  BLANC, Marie-France, (mfblanc@pasteur.fr) BREY, Paul,pbrey@pasteur.fr

CHOUMET, Valérie, IP,vchoumet@pasteur.fr

EIGLMEIER, Karin, IP,kei@pasteur.fr

PAUL, Richard, IP,topotito@pasteur.fr

RAIBAUD, Anna, IP,araibaud@pasteur.fr

ROSINSKI-CHUPIN, Isabelle, IP,ichupin@pasteur.fr

ROTH, Charles, CNRS, croth@pasteur.fr

BRAHIMI, Karima, IP, Postdoc,kbrahimi@pasteur.fr

GOMEZ, Shawn, Pasteur Foundation, Postdoc,sgomez@pasteur.fr

GRAILLES, Marine, IP Dakar, Postdoc,letocar@pasteur.fr

HAN, Sung-Jun, Yonsei Medical School, Corée, PhD student, a quitté l'unité le 30 avril 2002

JAN, Virginie, Museum Histoire Naturelle, PhD student,vjan@pasteur.fr

POLONSKY Alexander, Pasteur Foundation, Postdoc,apolonsk@pasteur.fr

VENERI, Massimiliano, Université de Rome, "la Sapienza", Student, a quitté l'unité le 4 novembre 2002
BLANC, Marie-France, IP, Secretary,mfblanc@pasteur.fr

CARMI-LEROY, Annick, IP, Technician,acarmi@pasteur.fr

HOLM, Inge, Engineer,holm@pasteur.fr

PATRICIO, Vidalia, IP, Technician,patricio@pasteur.fr

PERROT, Sylvie, IP, Technician,sperrot@pasteur.fr

ROBBE-VINCENT, Annie, IP, Technician,arobbe@pasteur.fr

SAUTEREAU, Jean, IP, Technician,jsautere@pasteur.fr

VINDU BOKOMO, Julia, IP, Laboratory Agent,jvindu@pasteur.fr

Activity Reports 2002 - Institut Pasteur
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