Impact of the Heat Shock Protein 100 on the Intracellular Survival of Leishmania Amastigote Stages

• Applicant: Privatdozent Dr. Joachim Clos
• Subject Area: Immunology
• Term: from 2002 to 2005
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5374613

Following entry into a mammalian host organism, Leishmania spp. are phagocytised by macrophages. Inside the phagosome, the elongated, flagellated promastigote stage converts into the round, aflagellated amastigote stage. As amastigotes, Leishmania parasites persist and proliferate, thereby destroying their host cells. The ability of Leishmania amastigotes to survive within the phagolysosome and to escape destruction is a key factor to their pathogenicity. The 100-kDa heat shock protein, Hsp100, of Leishmania plays a selective and crucial role in this process. delta clpB gene replacement mutants that lack Hsp100 are perfectly viable under axenic culture conditions. By contrast, inside mouse macrophages or during experimental infection of mice, these gene replacement strains show a marked decrease of virulence and an impaired intracellular survival. The expression of some amastigote-specific proteins is affected in the Hsp100-- mutants. We plan to identify the affected proteins and/or their corresponding genes and establish their importance for intracellular survival and virulence. To this end we propose a two-pronged approach: i) comparative proteome analysis of wild type and delta clpB mutants during and after amastigote differentiation, and ii) functional genetic complementation. The goal of this study is to gain insight into the processes that allow Leishmania species to escape destruction inside the macrophages and to proliferate within a hostile intracellular environment.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1131: Life Inside Cells