A new study has shown previously unseen details of an anthrax bacteriophage a virus that infects anthrax bacteria revealing for the first time how it infects its host, and providing an initial blueprint for how the phage might someday be modified into a tool for the detection and destruction of anthrax and other potential bioterror agents.
The bacteriophage, known as Bacillus anthracis spore-binding phage 8a (or SBP8a, for short), is too small to be seen with a conventional light microscope. To create a portrait of the virus, researchers employed cryo-electron tomography, using an electron microscope to image a flash-frozen sample from many different viewing angles. With the help of computers, the scientists then recombined these views to produce three-dimensional renderings of the phage.
One of the surprising initial results was that the samples imaged contained SBP8a in four distinctly different configurations. While all four states are generally similar, with globular "heads" and linear "tails," significant differences can be seen that the researchers believe correspond to different steps in the viral infection process.
"The images we made from these four major populations clearly show in three dimensions exactly how these remarkable nanodevices are able to penetrate the anthrax cell, release their DNA from the bacteriophage's head and ultimately control its flow through the phage tail and into the cell," said University of Texas Medical Branch at Galveston assistant professor Marc Morais, senior author of a paper on the study now online in Virology.
Each of SBP8a's different states is marked by four key substructures: a hockey-puck-shaped "baseplate" at the opposite end of the tail from the head; a hollow tube running from the head to the baseplate; a sheath formed by six strands that wind around the hollow tube; and SBP8a's neck, which lies at the intersection of the bacteriophage's tail and its DNA-con
|Contact: Kristen Hensley|
University of Texas Medical Branch at Galveston