标题：Poly(γ-d-glutamic acid) protein conjugates induce IgG antibodies in mice to the capsule of Bacillus anthracis: A potential addition to the anthrax vaccine
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2003
卷号：100
期号：15
页码：8945-8950
DOI：10.1073/pnas.1633512100
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Both the protective antigen (PA) and the poly({gamma}-D-glutamic acid) capsule ({gamma}DPGA) are essential for the virulence of Bacillus anthracis. A critical level of vaccine-induced IgG anti-PA confers immunity to anthrax, but there is no information about the protective action of IgG anti-{gamma}DPGA. Because the number of spores presented by bioterrorists might be greater than encountered in nature, we sought to induce capsular antibodies to expand the immunity conferred by available anthrax vaccines. The nonimmunogenic {gamma}DPGA or corresponding synthetic peptides were bound to BSA, recombinant B. anthracis PA (rPA), or recombinant Pseudomonas aeruginosa exotoxin A (rEPA). To identify the optimal construct, conjugates of B. anthracis {gamma}DPGA, Bacillus pumilus {gamma}DLPGA, and peptides of varying lengths (5-, 10-, or 20-mers), of the D or L configuration with active groups at the N or C termini, were bound at 5-32 mol per protein. The conjugates were characterized by physico-chemical and immunological assays, including GLC-MS and matrix-assisted laser desorption ionization time-of-flight spectrometry, and immunogenicity in 5- to 6-week-old mice. IgG anti-{gamma}DPGA and antiprotein were measured by ELISA. The highest levels of IgG anti-{gamma}DPGA were elicited by decamers of {gamma}DPGA at 10 -20 mol per protein bound to the N- or C-terminal end. High IgG anti-{gamma}DPGA levels were elicited by two injections of 2.5 {micro}g of {gamma}DPGA per mouse, whereas three injections were needed to achieve high levels of protein antibodies. rPA was the most effective carrier. Anti-{gamma}DPGA induced opsonophagocytic killing of B. anthracis tox-, cap+. {gamma}DPGA conjugates may enhance the protection conferred by PA alone. {gamma}DPGA-rPA conjugates induced both anti-PA and anti-{gamma}DPGA.
