Image:Courtesy William Wikoff/Scripps Institute of Research
Thankfully, this armored virus does not infect humans. Rather it belongs to a class of viruses known as bacteriophages, which only infect bacteria. Because of the virus's extremely small size (its head is thousands of times narrower than a human hair) researchers turned to electron microscopy and x-ray crystallography to examine its exterior. HK97's coat, they found, consists of 72 interlocking rings of protein--formidable protection for the virus's DNA. "Its protein rings are cross-linked in a manner similar to the five-ring Olympic symbol," notes Hiro Tsuruta of Stanford University. "Together the rings form a rigid, spherical cage shaped like a 20-sided soccer ball."
The viral armor may well function similarly to the ensembles of medieval knights, which offered both protection and freedom of movement. "This virus has developed a very clever way of keeping its DNA intact," Tsuruta observes. Nanotechnology investigators may take inspiration from this clever configuration. "People are looking at viruses as containers," remarks Scripps Research Institute biologist John E. Johnson, "and the chain mail structure could provide a novel way to create a container that's very thin yet stable."