Infection the Latent Period

The phage latent period begins with the eclipse, during which mature virions are not yet associated with phage-infected bacteria. The post-eclipse phase of an infection can be understood as a period of phage-progeny maturation since mature virions may be released from infected bacteria either following artificial lysis (36) or, as is the case for filamentous phage (see chapter 12), without host lysis. Maturation, for highly virulent phage, mostly occurs at a constant, linear rate rather than exponentially because the rate of synthesis of virion components is limited by the host's anatomy or physiology (42, 74). The situation is complicated, however, if cells are able to continue to grow and divide during phage infection. This is because ongoing growth of a

Table 5-1 Defining Phage Ecology

Ecology

A Bacterium is...

Considerations

Experiments

Organismal

Population

Community

Ecosystem

A bacterium is a target, or an entity that impacts on phage phenotype

A bacterium is an environmental resource

A bacterium is a partner in coevolution

A bacterium is a lower trophic level

Phage anatomy, physiology, and behavior characterized from an in situ or a Darwinian perspective; virion stability, survival, and adsorption; eclipse period, latent period, and burst size; adaptations overcoming barriers to transmission between hosts

Phage population growth and density; liquid versus spatially structured environments (broth growth versus plaque growth); low versus high phage multiplicity; lysogeny versus active phage replication; within-bacteria competition

Phage-host coevolution; impact of phage density on density of uninfected bacteria and vice versa; community stability; host resistance; phage host-range breadth and variation; transduction and phage (or lysogenic) conversion; interaction between different phage species

Phage impact on ecosystem nutrient cycling and energy flow; short-circuiting of the microbial loop; nutrient release from eukaryote tissues due to attack by phage-encoded toxins

Single-step growth; adsorption curves; kinetics of phage decay

Batch growth; plaque growth; phage stock preparation

Phage-host continuous-culture or serial-transfer experiments; in situ observation and experiment

In situ observation and experiment

Adsorption

Extracellular search 4

Diffusion

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