Immunological aspects of infections part 38

Viruses have evolved many mechanisms to evade the immune response, but one of the key  elements in these evasive mechanisms has been  their ability to induce a latent status within the cells of the host. Thus, all herpes viruses can remain latent, and no viral antigen is expressed. When there is a change in the host-virus equilibrium secondary to certain other infections, metabolic disturbances, immunosuppression, or aging, only then does the virus  reactivate and cause disease. Examples are herpes simplex in the trigeminal ganglia, which causes recurrent "cold sores", or herpes zoster  in a dorsal root ganglion, which causes "shingles".