FIG. 2.

Immunoblot demonstrating production of PA by recombinant anthrax strains. Sterilely filtered, concentrated culture supernatants were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis on 10 to 15% gradient gels, electroblotted to nitrocellulose, and probed with anti-PA antibodies. Panel A lanes: 1, ΔANR(pJB1); 2, ΔANR(pPA102); 3, ΔANR control with no plasmid; 4, ΔSterne(pJB1); 5, ΔSterne(pPA102); 6, ΔSterne control with no plasmid. Panel B lanes: 1, ΔANR control with no plasmid; 2, ΔANR(pJB3); 3, ΔSterne(pJB2); 4, ΔSterne(pJB3); 5, purified PA from the Sterne strain; 6, ΔSterne control with no plasmid. The positions of molecular mass standards (sizes are in kilodaltons) are indicated on the left. Approximately equal volumes were applied to all of the lanes.