title: A recombinant 63-kDa form of Bacillus anthracis protective antigen produced in the yeast Saccharomyces cerevisiae provides protection in rabbit and primate inhalational challenge models of anthrax infection.
abstract: Infection by Bacillus anthracis is preventable by prophylactic vaccination with several naturally derived and recombinant vaccine preparations. Existing data suggests that protection is mediated by antibodies directed against the protective antigen (PA) component of the anthrax toxin complex. PA is an 83-kDa protein cleaved in vivo to yield a biologically active 63-kDa protein. In an effort to evaluate the potential of yeast as an expression system for the production of recombinant PA, and to determine if the yeast-purified rPA63 can protect from a lethal inhalational challenge, the sequence of the 63-kDa form of PA was codon-optimized and expressed in the yeast Saccharomyces cerevisiae. Highly purified rPA63 isolated from Saccharomyces under denaturing conditions demonstrated reduced biological activity in a macrophage-killing assay compared to non-denatured rPA83 purified from Escherichia coli. Rabbits and non-human primates (NHP) immunized with rPA63 and later challenged with a lethal dose of B. anthracis spores were generally protected from infection. These results indicate that epitopes present in the 63-kDa from of PA can protect rabbits and non-human primates from a lethal spore challenge, and further suggest that a fully functional rPA63 is not required in order to provide these epitopes.
authors.affiliation: Merck Research Laboratories, West Point, PA 19486, USA.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Hepler
authors.forename: Rosemarie
authors.initials: R
authors.lastname: Kelly
authors.forename: Tessie B
authors.initials: TB
authors.lastname: McNeely
authors.forename: Hongxia
authors.initials: H
authors.lastname: Fan
authors.forename: Maria C
authors.initials: MC
authors.lastname: Losada
authors.forename: Hugh A
authors.initials: HA
authors.lastname: George
authors.forename: Andrea
authors.initials: A
authors.lastname: Woods
authors.forename: Leslie D
authors.initials: LD
authors.lastname: Cope
authors.forename: Alka
authors.initials: A
authors.lastname: Bansal
authors.forename: James C
authors.initials: JC
authors.lastname: Cook
authors.forename: Gina
authors.initials: G
authors.lastname: Zang
authors.forename: Steven L
authors.initials: SL
authors.lastname: Cohen
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Wei
authors.forename: Paul M
authors.initials: PM
authors.lastname: Keller
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Leffel
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Joyce
authors.forename: Louise
authors.initials: L
authors.lastname: Pitt
authors.forename: Loren D
authors.initials: LD
authors.lastname: Schultz
authors.forename: Kathrin U
authors.initials: KU
authors.lastname: Jansen
authors.forename: Myra
authors.initials: M
authors.lastname: Kurtz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000881:Anthrax / Q000517:prevention & control*; D022122:Anthrax Vaccines / Q000276:immunology*; D000942:Antigens, Bacterial / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D001427:Bacterial Toxins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D003062:Codon; D005260:Female; D008253:Macaca mulatta; D008297:Male; D008969:Molecular Sequence Data; D011817:Rabbits; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000276:immunology; D012441:Saccharomyces cerevisiae / Q000235:genetics; D014614:Vaccines, Synthetic / Q000276:immunology*
chemical_list: D022122:Anthrax Vaccines; D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D003062:Codon; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic; C030325:anthrax toxin