title: Experimental cutaneous Bacillus anthracis infections in hairless HRS/J mice.
abstract: Previous studies of experimental Bacillus anthracis cutaneous infections in mice have implicated hair follicles as a likely entry site. Hairless HRS/J mice were used to investigate this possibility because of their non-functional hair follicles that lack penetrating hair shafts. These mice also have diminished macrophage function, increased susceptibility to Listeria, and enhanced neutrophil responses. HRS/J and Balb/c mice were found to be resistant to epicutaneous inoculation with Bacillus anthracis (Sterne) spores onto abraded skin when compared with DBA/2 mice or leucopenic C57BL/6 mice. The HRS/J mice also resisted spore injections that bypassed hair follicles. Haired HRS/J heterozygote mice demonstrated similar reduced susceptibility to B. anthracis spores. Hairless HRS/J mice that were made leucopenic did become susceptible to the epicutaneous spore inoculations. Histologically, the hairless and haired HRS/J mice showed markedly reduced numbers of organisms in hair follicles and the interfollicular dermis when compared even with the resistant Balb/c mice; inflammatory cell infiltrates in the superficial dermis were increased in the HRS/J mice compared with more sensitive strains. Therefore, resistance in the HRS/J mice was apparent at the initial site of epicutaneous inoculation and seemed related to an accumulation of dermal neutrophils rather than to a lack of functional hair follicles.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Medical College of Wisconsin, and Consultant Care Division and Research Service, VA Medical Center, Milwaukee, WI 53295, USA.
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Bischof
authors.forename: Beth L
authors.initials: BL
authors.lastname: Hahn
authors.forename: Peter G
authors.initials: PG
authors.lastname: Sohnle
mesh_terms: D000818:Animals; D000881:Anthrax / Q000276:immunology* / Q000473:pathology / Q000635:transmission; D001408:Bacillus anthracis; D002452:Cell Count; D018859:Hair Follicle / Q000276:immunology / Q000473:pathology; D007113:Immunity, Innate; D007271:Injections, Intradermal; D051379:Mice; D008812:Mice, Hairless / Q000276:immunology*; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008815:Mice, Inbred Strains; D023421:Models, Animal; D012867:Skin / Q000276:immunology / Q000473:pathology; D012874:Skin Diseases, Infectious / Q000276:immunology* / Q000473:pathology / Q000635:transmission; D013171:Spores, Bacterial