title: Demonstration of a capsule plasmid in Bacillus anthracis.
abstract: Virulent and certain avirulent strains of Bacillus anthracis harbor a plasmid, designated pXO2, which is involved in the synthesis of capsules. Two classes of rough, noncapsulated (Cap-) variants were isolated from the capsule-producing (Cap+) Pasteur vaccine strains ATCC 6602 and ATCC 4229. One class was cured of pXO2, and the other class still carried it. Reversion to Cap+ was demonstrable only in rough variants which had retained pXO2. Proof that pXO2 is involved in capsule synthesis came from experiments in which the plasmid was transferred by CP-51-mediated transduction and by a mating system in which plasmid transfer is mediated by a Bacillus thuringiensis fertility plasmid, pXO12. Cells of Bacillus cereus and a previously noncapsulated (pXO2-) strain of B. anthracis produced capsules after the acquisition of pXO2.
mesh_terms: D001408:Bacillus anthracis / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology; D001409:Bacillus cereus / Q000235:genetics; D001413:Bacillus thuringiensis / Q000235:genetics; D001435:Bacteriophages / Q000235:genetics; D002473:Cell Wall / Q000502:physiology; D003227:Conjugation, Genetic; D014644:Genetic Variation; D005838:Genotype; D049690:History, Ancient; D010957:Plasmids; D013045:Species Specificity; D014161:Transduction, Genetic; D014774:Virulence