Viruses like pox and herpes are crafty parasites. Unable to replicate on their own, they pump their DNA into infected cells, and use their host’s replication machinery to do the job for them. This computer model of a viral particle, or virion, is reconstructed from hundreds of images of cryogenically-preserved particles, made possible with a technique called electron cryo-microscopy (cryo-EM). Ten million-times smaller than a tomato-shaped ketchup bottle, the virion uses a 'nozzle' (highlighted in grey) to squeeze its DNA (multi-coloured inner circles, right) out into host cells. Newly-produced virions use similar channels to suck up copies of the viral DNA, ready to infect other cells. Using cryo-EM to highlight architectural details in virions – shown from the front (left) and sliced open from above (right) – provides clues about how infections spread, and may influence therapies to intervene at crucial stages in the virus’ life cycle.
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.
BPoD is also available in Catalan at www.bpod.cat with translations by the University of Valencia.