Viral Armour

A virus has a girth of only a few thousand atoms –so small, they can infect bacteria. These microscopic entities are protected by a protein shell or capsid, which grows and changes shape as the virus matures. Seen by Atomic Force Microscopy, young HK97 viruses – similar to the cold sore virus Herpes simplex – are pentagon-shaped (top left). They mature into football-like structures (bottom left). Arranged in a regular pattern of hexagons and pentagons, shell protein connections or cross-links increase with age. CGI (yellow and blue hexagons) highlights the changing structure (right-hand images). To test viral vulnerability researchers prodded capsids with tiny probes. While the more mature HK97 virus has chainmail-like armour its extra cross-links add surprisingly little strength. However, they do provide durability – the younger capsids disintegrate after relatively few pokes. Identifying weak points in the viral life cycle will inform the design of effective drugs.

Written by Alice Lighton

Alice Lighton

Writer

Since completing her physics degree at Oxford, Alice has worked at Wired and Technology World magazines, and was deputy editor of The Oxford Student. She writes on tropical disease and bicycles.

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• Image Courtesy of Gijs Wuite
• Published in PNAS