Enhancement of antibody responses to Bacillus anthracis protective antigen domain IV by use of calreticulin as a chimeric molecular adjuvant

Sung Park Yong, Hyup Lee Jin, Chien Fu Hung, T. C. Wu, Woo Kim Tae

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


The generation of protective humoral immune responses against the receptor-binding domain (domain IV) of protective antigen [PA(dIV)] of Bacillus anthracis represents a plausible approach against anthrax toxin. In the current study, we have developed a naked DNA vaccine encoding calreticulin (CRT) linked to PA(dIV) of Bacillus anthracis [CRT/PA(dIV)]. We transfected a human embryonic kidney cell line (HEK 293) with CRT/PA(dIV) DNA and performed Western blotting and confocal microscopy analysis. We found that linkage of CRT to PA(dIV) targets PA(dIV) to the endoplasmic reticulum, resulting in secretion of the chimeric CRT/PA(dIV) protein. We then evaluated the ability of CRT/PA(dIV) DNA to generate PA(dIV)-specinc antibody responses and protective immunity against lethal anthrax toxin (PA plus lethal factor) challenge. We found that mice immunized with CRT/PA(dIV) DNA were capable of rapidly inducing significantly higher PA(dIV)-specific antibody responses than mice immunized with PA(dIV) DNA alone. Furthermore, we observed that this enhanced antibody response generated by CRT/PA(dIV) DNA was CD4 dependent, since CD4 knockout mice demonstrated a significant reduction in antibody responses. In addition, analysis of the titers and avidity maturation of the induced PA-specific antibodies revealed that vaccination with CRT/PA(dIV) DNA vaccine accelerated the avidity maturation of antibodies to PA(dIV) compared to vaccination with PA(dIV) DNA. Importantly, the enhanced antibody responses correlated to protective immunity against lethal anthrax toxin challenge. Thus, DNA vaccines encoding CRT linked to PA(dIV) may dramatically enhance PA-specific protective antibody responses. Our results have significant clinical applications for biodefense against anthrax toxin.

Original languageEnglish (US)
Pages (from-to)1952-1959
Number of pages8
JournalInfection and immunity
Issue number5
StatePublished - May 2008

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases


Dive into the research topics of 'Enhancement of antibody responses to Bacillus anthracis protective antigen domain IV by use of calreticulin as a chimeric molecular adjuvant'. Together they form a unique fingerprint.

Cite this