Bacteriophage T4, a virus that infects E.Coli, has played key roles in some of the major advances in the molecular biology field including the identification of the chemical nature of the gene, elucidating the mechanism of DNA replication, discovering that genes code for proteins, and even deciphering how the genetic code is read. Virology Journal has published its first thematic series, Bacteriophage T4 and its relatives (a series of critical reviews), to highlight the latest advances in T4 biology, focusing on four areas of research: genomics, gene expression, DNA replication and phage morphology.
T4 –related phages are found in marine environments where they exert control of the ecosystem through their interaction with their host bacteria. T4-like cyanophages that infect cyanobacteria have an impact on the marine ecosystem. A fascinating feature of cyanophages is that they possess genes of host bacterial origin, including those involved in photosynthesis. T4-related phages produce homing endonucleases that mediate gene transfer. Homing endonucleases are thought to have played a major role in phage and bacterial evolution.
Comparisons of the genomes of 40 phages that infect a variety of bacteria, but are related to bacteriophage T4, reveal a great degree of genetic diversity, but interestingly the genes that control replication, expression and phage packaging remain highly conserved among the phages, implying that these genes are vital to the phages and slight variations could impede phage functionality.
The series concludes with reviews on the current knowledge in phage head and tail assembly, these mechanisms could potentially be exploited in the development of vaccines and phage therapy. This series is timely because there has been a recent increased interest in bacteriophages as sources of toxins and therapeutic agents against targeted bacterial pathogens.