Of these, experts agree, the smallpox virus is in a class by itself.

Thus, the initial search was for signs of smallpox viruses.

A dispute continues on whether to preserve the smallpox virus itself for future study.

We know, however, that the smallpox virus still exists in laboratories.

American officials fear that Iraq may have the smallpox virus and might use it.

The smallpox virus killed an estimated 10 to 15 million human beings per year until 1967.

The smallpox virus remains as the most notable member of the family.

However, the smallpox virus should be extremely difficult for a terrorist to get.

The government has called the risk of an attack with smallpox virus low and said that its request did not reflect new information.

Information that the smallpox virus is in the hands of terrorist groups has not been confirmed.