The viruses that infect bacteria are the most abundant biological entities on the planet. For example, a recent simple study of 92 showerheads and 36 toothbrushes from American bathrooms found more than 600 types of bacterial viruses, commonly called bacteriophages or phages. A teaspoon of coastal seawater has about 50 million phages.
While largely unnoticed, phages do not harm humans. On the contrary, these viruses are gaining increasing popularity as biomedicines to eradicate pathogenic bacteria, especially those associated with antibiotic-resistant infections. In a study published in the journal Nature Communications, Gino Cingolani, Ph.
D., of the University of Alabama at Birmingham, and Federica Briani, Ph.D.
, of the Università degli Studi di Milano, Milan, Italy, have described the full molecular structure of the phage DEV. DEV infects and lyses Pseudomonas aeruginosa bacteria, an opportunistic pathogen in cystic fibrosis and other diseases. DEV is part of an experimental phage cocktail developed to eradicate P.
aeruginosa infection in pre-clinical studies. A peculiar feature of DEV is the presence of a 3,398-amino acid virion-associated RNA polymerase inside the capsid expelled into the bacterium upon infection. Unexpectedly, Cingolani and Briani's study revealed the virion-associated RNA polymerase is part of a genome ejection motor that pulls the DNA of the phage out of its head after the phage has attached to the surface of a Pseudomonas bacteria using its tail fib.
