Experimental Cutaneous Bacillus Anthracis Infections in Hairless HRS/J Mice

The study investigated the role of hair follicles in cutaneous Bacillus anthracis infections using hairless HRS/J mice, which have non-functional hair follicles. The research found that both hairless HRS/J and haired HRS/J heterozygote mice were resistant to epicutaneous inoculation with B. anthracis spores on abraded skin, compared to DBA/2 mice or leucopenic C57BL/6 mice. This resistance was also observed when spores were injected in a way that bypassed hair follicles. However, when HRS/J mice were made leucopenic, they became susceptible to infection. Histological examination showed fewer organisms in the hair follicles and interfollicular dermis of HRS/J mice compared to Balb/c mice, and an increased inflammatory cell infiltrate in the superficial dermis of HRS/J mice. The study concluded that the resistance in HRS/J mice to B. anthracis was due to an accumulation of dermal neutrophils rather than the absence of functional hair follicles.