The key mission of viruses is to spread within its ecological niche. To achieve their mission viruses must multiply efficiently, be available at appropriate body sites for transmission and yet not kill the host since extreme virulence that kills the host curtails the spread of viruses in a population as illustrated by SARS and Ebola viruses. HSV infects a very large fraction of human population and is therefore a successful pathogen. To achieve it mission the virus encodes functions of omission that fail to block host immune responses and functions of commission that specifically curtail its replication. The net effect is the evolution of a pathogen that controls its replication so as to maintain a high level of contacts between infected and uninfected individuals.