Lethal weapon used by viruses

It could be the tiniest armor-piercing weapon in the biological universe: Scientists have measured a one-nanometer needle-like tip that viruses use to attack bacteria. Grouped together under the unassuming name φ92, a family of bacteriophage viruses has perfected its specialty: they attack salmonella and coliform bacteria. The centerpiece of their arsenal is a needle-like tip that pierces its victim's membrane. EPFL scientists have measured this miniscule weapon; at a single nanometer, it's roughly 20 times the diameter of a helium atom. This discovery will allow researchers to better understand the attack strategy used by bacteriophages, which are being intensively studied for their therapeutic potential. φ92's armor-piercing weapon is made up of three chains of identical proteins. These three long intertwined molecules form an appendage sharp enough to penetrate the bacterial membrane.