Leishmania major Hsp100 is required chiefly in the mammalian stage of the parasite.
In Leishmania major a 100-kDa heat shock protein, Hsp100, is abundant in the intracellular amastigote stage which persists in the mammalian host. A replacement of both clpB alleles which encode Hsp100 does not affect promastigote viability under standard culture conditions but impairs thermotolerance in vitro. In experimental infections of BALB/c inbred mice, the lack of Hsp100 in the gene replacement mutants results in a markedly delayed lesion development compared with that in infections with wild-type L. major. Overexpression of exogenous clpB gene copies can partly restore virulence to the gene replacement mutants. Genetic-selection experiments also reveal a strong pressure for Hsp100 expression in the mammalian stage. This requirement for Hsp100 was also observed in in vitro infection experiments with mouse peritoneal macrophages. These experiments indicated a role for Hsp100 during the development from the promastigote to the amastigote stage. Our results suggest an important role for this parasite heat shock protein during the initial stages of a mammalian infection.
Hübel
A
A
Leishmaniasis Unit, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
Krobitsch
S
S
Hörauf
A
A
Clos
J
J
D000818:Animals; D002478:Cells, Cultured; D049071:Endopeptidase Clp; D005786:Gene Expression Regulation; D018390:Gene Targeting; D006360:Heat-Shock Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D006358:Hot Temperature; D018320:Leishmania major / Q000737:chemistry / Q000254:growth & development / Q000472:pathogenicity*; D016773:Leishmaniasis, Cutaneous / Q000469:parasitology; D017737:Macrophages, Peritoneal / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D015800:Protozoan Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D011995:Recombination, Genetic; D014774:Virulence
D006360:Heat-Shock Proteins; D015800:Protozoan Proteins; D049071:Endopeptidase Clp; C095049:ClpB protein, Leishmania