Biophysical characterization and immunization studies of dominant negative inhibitor (DNI), a candidate anthrax toxin subunit vaccine

Abstract

Dominant negative inhibitor (DNI) is a translocation-deficient homolog of recombinant protective antigen of Bacillus anthracis that is a candidate for a next generation anthrax vaccine. This study demonstrates that the biophysical characteristics of the DNI protein stored in lyophilized form at 4 °c for 8 y were similar to recombinant protective antigen (rPa). To provide information on the accelerated stability of DNI, samples in the lyophilized form were subjected to thermal stress (40 and 70 °c for up to 4 weeks) and thoroughly evaluated using various biophysical and chemical characterization techniques. Results demonstrate preserved structural stability of the DNI protein under extreme conditions, suggesting long-term stability can be achieved for a vaccine that employs DNI, as desired for a biodefense countermeasure. Furthermore, the biological activity of the stressed DNI bound to the adjuvant alhydrogel® was evaluated in mice and it was found that the immunogenicity of DNI was not affected by thermal stress. © 2013 Landes Bioscience.