Virii and bacteria are fascinating. The mechanisms by which a virus works are nothing short of amazing from an engineering and automata theory process.
A virus is a rather simple device with an ingenious design (I use the term "design" loosely here: all you ID purists can go take a flying pothole). The primary building blocks are protiens which form into "parts" for a "machine":
The baseplate is composed of 16 types of protein molecules, most present in multiple copies. Before infection, these proteins fit together to form a hexagonal shape. Together with the 12 legs that extend from the T4's tail to grasp the victim E. coli, the virus resembles an Apollo moon lander. When the T4 approaches "touchdown" on an E. coli's cell membrane, the baseplate's proteins unfold in a complex motion, opening like a flower's petals and changing shape from a hexagon to a star.
This is the future of nanomachines. Protien engineering.