Survival of phages

Abstract

The phage virion is essentially a survival mechanism designed to protect the phage genome from the rigors of the environment to which it is exposed when it destroys its host and to get it into a new host when such becomes available. It is clearly efficient, otherwise phages would long ago have become extinct, yet it is common knowledge that phage preparations in the laboratory gradually lose their infectivity and eventually become useless. An understanding of the factors that affect survival of phages is thus important for anyone who intends to work with them. Furthermore, valuable knowledge of the fundamental nature of a phage may be gained by observing how it survives deliberate insults. The term ‘survival’ can be construed in many ways, making it important to define certain terms at the outset. Survival may imply survival as an object recognisable in the electron microscope as a phage, i.e. not utterly destroyed, but most workers take it to mean the retention of infectivity as shown by the formation of plaques or the clearing of broth cultures.