Additional Conjugation Methods and Immunogenicity of Bacillus anthracis Poly-γ- d -Glutamic Acid-Protein Conjugates

Abstract

The capsule of Bacillus anthracis, composed of poly-␥-D-glutamic acid (␥DPGA), is an essential virulence factor of B. anthracis. The capsule inhibits innate host defense through its antiphagocytic action. ␥DPGA is a poor immunogen, but when covalently bound to a carrier protein, it elicits serum antibodies. To identify the optimal construct for clinical use, synthetic ␥DPGAs of different lengths were bound to carrier proteins at different densities. The advantages of the synthetic over the natural polypeptide are the homogeneous chain length and end groups, allowing conjugates to be accurately characterized and standardized and their chemical compositions to be related to their immunogenicities. In the present study, we evaluated, in addition to methods reported by us, hydrazone, oxime, and thioether linkages between ␥DPGA and several proteins, including bovine serum albumin, recombinant Pseudomonas aeruginosa exotoxin A, recombinant B. anthracis protective antigen (rPA), and tetanus toxoid (TT). The effects of the dosage and formulation on the immunogenicities of the conjugates were evaluated in mice. All conjugates were immunogenic. The optimal ␥DPGA chain length of 10 to 15 amino acids and the density, an average of 15 mol ␥DPGA per mol of protein, were confirmed. The thioether bond was the optimal linkage type, and TT and rPA were the best carriers. The optimal dosage was 1.2 to 2.5 g of ␥DPGA per mouse, and adsorption of the conjugates onto aluminum hydroxide significantly increased the antibody response to the protein with a lesser effect on anti-␥DPGA levels.

An Oxycodone Conjugate Vaccine Elicits Drug-Specific Antibodies that Reduce Oxycodone Distribution to Brain and Hot-Plate Analgesia

“…Linker composition and length contribute to conjugate vaccine immunogenicity (Kubler-Kielb et al, 2006), but the extent of this contribution is often difficult to interpret because the corresponding haptenation ratios for the conjugates be- jpet.aspetjournals.org ing compared are not reported. Greater conjugate immunogenicity could be caused by enhanced recognition by antigenpresenting or B cells but could also be caused by differences in carrier protein haptenation because higher haptenation ratios are generally associated with greater immunogenicity (Carroll et al, 2011).…”

Saccharide/protein conjugate vaccines for Bordetella species: Preparation of saccharide, development of new conjugation procedures, and physico-chemical and immunological characterization of the conjugates

“…The choice of conjugation methods is restricted by the pH and temperature sensitivities of both vaccine components. The types of chemical linkages between the O-SP and the protein as well as the saccharide chain length and the chain density on the protein were shown to influence the serum antibody responses to both vaccine components [35,36,37,38,39,40]. Here we studied two conjugation methods of O-SP either by their Kdo or their glucosamine residues.…”

Computer‐assisted 2‐D agarose electrophoresis of Haemophilus influenzae type B meningitis vaccines and analysis of polydisperse particle populations in the size range of viruses: A review

“…Potentially, such an analysis may be beneficial for a variety of other protein-capsular conjugates that have been produced as immunogens for the protection against infection from several bacteria (overview in [9]); e.g., Streptococcus pneumoniae [21,22], Staphylococcus aureus [23], Neisseria meningitidis [24], Escherichia coli O157:H7 [25], and B. anthracis [26]. The latter has been considered the most likely biowarfare weapon [27] and is the subject of current biodefense strategies.…”