Production of stress-inducible form of heat-shock protein 70 in mouse peritoneal adherent cells after in vivo infection by Francisella tularensis.

Heat-shock proteins (hsp) are ubiquitously produced molecules which participate in the protection of cells from environmental perturbation. Moreover, the members of the heat-shock protein 60 (hsp60) and 70 (hsp70) families play an important role in pathogen-host interactions. We studied in vivo production of the 70-kDa heat-shock proteins in the extract of peritoneal exudate cells (PEC) from mice injected intraperitoneally with an attenuated vaccine strain (LVS) of Francisella tularensis. We found a differential production of a highly stress-inducible member of the hsp70 family, designated hsp72, in three inbred strains of mice exhibiting either resistance or susceptibility to F. tularensis LVS infection. Whereas in tularemia-resistant mice hsp72 was even expressed in PEC without injection of bacteria and its production further increased on day 3 and slowly declined on days 5 and 7 after injection, in susceptible mice hsp72 production was highly inducible and restricted only to day 3 after in vivo infection. Further analysis of hsp72 expression revealed intracellular hsp72 accumulation and its preferential production by peritoneal adherent cells.