1.   Although the other pox viruses can infect several different species, smallpox is a disease of humans only.

2.   Among them is one genetically engineered from a weakened form of the canary pox virus.

3.   And no studies may be carried out in a laboratory where other pox viruses are kept.

4.   Animals given the drug before or shortly after exposure to pox virus survive, whereas untreated animals die.

5.   A handful of vaccine candidates, including a federally supported one involving a weakened canary pox virus, are at various stages of development.

6.   In the animal tests, a single dose of the drug was effective against pox virus for seven days.

7.   Some volunteers who receive the diluted vaccine, which is a live pox virus, may come down with disease, and will be treated with cidofovir.

8.   Thompson said the federal government is equally prepared to deal with an attack using the small pox virus.

9.   Otherwise, testing must be done with related microbes, such as the monkey pox virus, that naturally target animals.

10.   The small pox virus, for instance, has only about a tenth of the DNA bases found in the Hemphilus influenzae.