Bacillus anthracis

Abstract

Bacillus anthracis, the causative agent of anthrax, is the only member of the genus Bacillus that is capable of causing epidemic disease in humans and other mammals. The capsule is one of the virulence factors of B. anthracis. Evidence that bicarbonate is involved in the regulation of capsule synthesis is presented in the discussion of the capsule plasmid pX02. For several years, it was believed that the anthrax toxin was made up of only two components, but it was later established that the toxin actually consists of three proteins. It has been demonstrated that lethal factor (LF) in combination with protective antigen (PA) lysed mouse peritoneal macrophages, as evidenced by loss of lactic dehydrogenase activity. This in vitro system for studying anthrax lethal toxin activity should expedite one's understanding of the toxic reaction. Gene exchange systems performed by transduction, transformation (transfer of plasmids by mating) and transposon mutagenesis are discussed. One of the most active reactions was that between D-phenylalanine and pyruvate, forming alanine and phenylpyruvate. The vaccine commonly used to immunize livestock against anthrax vaccines consists of live spores of a toxigenic, noncapsulated strain, i.e., a strain that has been cured of the capsule plasmid, pXO2, but still carries the toxin plasmid, pXO1. The principal antigen in the vaccine is PA. Several doses of PA vaccines have to be given initially, and frequent booster doses are necessary to sustain antibody titers.