Researchers from Canada and the United States have developed a drug that could someday be used to treat people exposed to anthrax bacteria specifically engineered to overcome antibiotics.

In the past five years, new technology has made it easier to genetically modify microbes and even create new ones from scratch. Some worry that the developments could lead to novel and more dangerous kinds of bioterror threats.

The top officials charged with protecting the United States against a biological attack played down concerns that a new agent could exterminate the human race but warned that the threat of new, engineered pathogens remains serious.

Officials testified before congress on the multiple avenues of defense the U.S. is pursuing against a possible terrorist attack using bioengineered pathogens.

Recent technological advances in so-called genetic circuits have brought closer a world where cells and viruses could be modified to more effectively serve humans, but also have raised concerns that programmable life could lead to a host of tailored threats similar to Internet worms.

Terrorists could employ new, advanced technologies to conduct attacks with the potential to cause mass casualties according to a U.S. terrorism expert.

Senior scientific advisers to the World Health Organisation (WHO) have recommended the creation of a genetically modified version of the smallpox virus to counter any threat of a bioterrorist attack.

Researchers have made an unexpectedly sudden advance in synthesizing long molecules of DNA, creating concern the technique might be used to create the smallpox virus.

An influential World Health Organization committee has upset some scientists with its recommendation that researchers be permitted to conduct genetic-engineering experiments with the smallpox virus.

A Bush administration program intended to guard against bioterrorism could actually make it more likely that the United States would be threatened with novel biological agents for which there are no vaccines or other defenses.