Figure 2.

Host microbe interaction: the precarious relationship between immune privilege (IP) and latent infection. Microbial challenge and invasion of the host through external barriers (cartoon on right) causes acute inflammation and spread of infection with one of three outcomes (box in centre). The host survives if the infection is fully cleared or if the infection becomes latent. Keeping microbes in a latent state depends not only on a conducive (“privileged”) microenvironment such as that in the CNS but on a sustained immune response. The microbe can reactivate when IP is breached by immune dysregulation (cartoon on left).