Herpes learns how to play nicely...

Or, integration steps of a former parasite:

The conventional view of herpes virus infections is that they are either active and harmful, or at best silent and for the time being harmless. But new work on mice suggests a third option: there may be a direct benefit for chronic herpesvirus infection. Latent infection with the murine HV68 confers prolonged cross-protection against a variety of bacterial pathogens, including Listeria and the plague bacillus. The protection is a result of systemic macrophage activation triggered by -interferon. The latent virus thereby sets the level of innate immunity. Not only is latency an active immunologic state, but this activity provides symbiotic benefit.

Taken from Nature's latest issue.

Something that Carl Zimmer will likely write about.