Factors involved in the germination and inactivation of Bacillus anthracis spores in murine primary macrophages.
Since macrophages have been implicated in inhalation anthrax either for defense and/or as enablers for spore trafficking, their function has been further defined. Spores were efficiently taken up by primary mouse bone marrow-derived macrophages even in the absence of serum but a minimal amount was required for spore germination and subsequent inactivation. With 10% fetal bovine serum (FBS) virtually all of the spores germinated but when the concentration of FBS was lowered to 1.0% or less, or when 10% horse serum replaced FBS, only 50% of the spores were inactivated within 1 h with no subsequent loss. Chloramphenicol, which blocks spore outgrowth but not germination, did not inhibit spore killing in macrophages. Based on complete inhibition of germination by d-alanine plus d-histidine, it is likely that only two of the several Bacillus anthracis germination systems are involved within macrophages. d-Histidine inhibits the gerH system previously implicated in germination within macrophages. d-Alanine is likely to block the gerX system since disruption of the gerXA gene resulted in little germination within 4 h in macrophages. Macrophages provide a major line of defense against infection by efficiently sequestering spores and in the presence of minimal nutrients effectively killing those that germinate before outgrowth.
Hu
Haijing
H
Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.
Emerson
James
J
Aronson
Arthur I
AI
D000818:Animals; D000881:Anthrax / Q000276:immunology* / Q000382:microbiology; D001408:Bacillus anthracis / Q000276:immunology* / Q000502:physiology; D002478:Cells, Cultured; D015169:Colony Count, Microbial; D003470:Culture Media / Q000737:chemistry; D005260:Female; D008264:Macrophages / Q000276:immunology / Q000382:microbiology*; D051379:Mice; D008815:Mice, Inbred Strains; D050296:Microbial Viability; D044967:Serum / Q000276:immunology; D013171:Spores, Bacterial / Q000254:growth & development / Q000276:immunology
D003470:Culture Media