title: Global analysis of host response to induction of a latent bacteriophage.
abstract: BACKGROUND
  The transition from viral latency to lytic growth involves complex interactions among host and viral factors, and the extent to which host physiology is buffered from the virus during induction of lysis is not known. A reasonable hypothesis is that the virus should be evolutionarily selected to ensure host health throughout induction to minimize its chance of reproductive failure. To address this question, we collected transcriptional profiles of Escherichia coli and bacteriophage lambda throughout lysogenic induction by UV light.
  
  
  RESULTS
  We observed a temporally coordinated program of phage gene expression, with distinct early, middle and late transcriptional classes. Our study confirmed known host-phage interactions of induction of the heat shock regulon, escape replication, and suppression of genes involved in cell division and initiation of replication. We identified 728 E. coli genes responsive to prophage induction, which included pleiotropic stress response pathways, the Arc and Cpx regulons, and global regulators crp and lrp. Several hundred genes involved in central metabolism, energy metabolism, translation and transport were down-regulated late in induction. Though statistically significant, most of the changes in these genes were mild, with only 140 genes showing greater than two-fold change.
  
  
  CONCLUSIONS
  Overall, we observe that prophage induction has a surprisingly low impact on host physiology. This study provides the first global dynamic picture of how host processes respond to lambda phage induction.
authors.affiliation: Department of Bioengineering and Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA. reosterhout@berkeley.edu
authors.forename: Robin E
authors.initials: RE
authors.lastname: Osterhout
authors.forename: Israel A
authors.initials: IA
authors.lastname: Figueroa
authors.forename: Jay D
authors.initials: JD
authors.lastname: Keasling
authors.forename: Adam P
authors.initials: AP
authors.lastname: Arkin
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics* / Q000528:radiation effects; D004926:Escherichia coli / Q000235:genetics* / Q000528:radiation effects / Q000821:virology*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D015967:Gene Expression Regulation, Viral; D008969:Molecular Sequence Data; D039002:Prophages / Q000235:genetics* / Q000528:radiation effects; D013997:Time Factors; D014466:Ultraviolet Rays; D014775:Virus Activation / Q000235:genetics* / Q000502:physiology