Some scientists are now genetically engineering a range of viruses that act as search-and-destroy missiles: selectively infecting and killing cancer cells while leaving healthy ones alone. This new strategy, called virotherapy, has shown promise in animal tests, and clinical trials involving human patients are now under way.

Scientists reported yesterday that they had constructed a virus from scratch for the first time, synthesizing a live polio virus from chemicals and publicly available genetic information.

Scientists have assembled the first synthetic virus. The US researchers built the infectious agent from scratch using the genome sequence for polio.

Researchers in New York have created infectious polioviruses from ordinary, inert chemicals they obtained from a scientific mail-order house, marking the first time a functional virus has been made from scratch and raising a host of new scientific and ethical concerns.

Researchers at the University of Texas at Austin have shown they can take advantage of these viral strong points by harnessing billions of the phages to build useful materials molecule-by-molecule.