Biopesticide and Bioweapons.

• Author: Cummins, Joseph
• Position: Biodevastation - Brief Article

Bacillus anthracis, the cause of anthrax poisoning, is currently a great concern because of its employment as a terror weapon. Bacillus thuringiensis is both a major pesticide and the source of the genes used to produce insect toxins in GM crops. A third bacterium, Bacillus cereus, is a common soil bacterium and a common cause of food poisoning. The three species of bacteria are closely related, differing mainly in their plasmids (plasmids are circular DNA molecules that replicate independently of the chromosome). The plasmids of the three species may readily be transferred from one species to another (1). The toxin genes from the three species are located on the plasmids and the genes tend to cluster in "islands" that sometimes are mobilized by viruses that integrate themselves into the plasmid as prophage. The ready exchange of plasmids bearing toxin genes between the three species has raised some concern (2).

The virulence of B. anthracis depends on the presence of two large plasmids; strains lacking one or the other plasmid are not virulent. Plasmid X02 carries genes that make polymers of glutamic acid (1 of 20 amino acids that make proteins). These glutamic acid polymers go on the cell surface to inhibit phagocytes, cells in the body that engulf and take in bacteria and digest them. Plasmid X01 carries the three toxin genes coding for edema factor, lethal factor and protective antigen (3).

The endotoxins of B. thuringiensis (bt toxins) are stored as inactive crystals in bacterial spores, which create pores on the cells of the insect gut, causing an inrush of water that bursts the cell. In the event that B. anthracis were to transfer plasmids to B. thur-ingiensis, recombination could create plasmids bearing toxins both for anthrax and for killing insects. New strains of B. anthracis with unpredictable properties could arise.

The bt toxin genes are employed in crop genetic engineering. Currently, there has been little or no effort to evaluate the possible recombination between B. anthracis in the field and the endotoxin genes of crop plants.

Such gene exchange could occur in the soil between GM plant debris and bacteria.

Also, it is not unlikely that GM crops carrying anthrax genes could be produced either for vaccines or for bio-weapons.

There is an extensive history of the use of bio-warfare agents...