Protection against anthrax with recombinant virus-expressed protective antigen in experimental animals

Area of Science:

• Microbiology
• Immunology
• Vaccinology

Background:

• Bacillus anthracis infection, or anthrax, poses a significant biodefense threat.
• Development of effective anthrax vaccines is crucial for public health and security.
• Protective antigen (PA) is a key component of anthrax toxins and a target for vaccine development.

Purpose of the Study:

• To clone and express the Bacillus anthracis protective antigen (PA) gene.
• To characterize the antigenicity and immunogenicity of recombinant PA produced in different expression systems.
• To evaluate the protective efficacy of recombinant PA against anthrax challenge.

Main Methods:

• Gene cloning and expression of Bacillus anthracis PA in vaccinia virus and baculovirus vectors.
• Characterization of PA antigenicity and antibody responses in immunized animals.
• Challenge studies in guinea pigs and mice using lethal Bacillus anthracis spores.

Main Results:

• Vaccinia virus-expressed PA (WR-PA) provided partial protection (60% in mice, 50% in guinea pigs) against anthrax challenge.
• Baculovirus-expressed PA, purified and combined with adjuvant, offered partial protection in mice and complete protection in guinea pigs.
• Both recombinant and non-recombinant PA preparations induced high anti-PA antibody titers in guinea pigs and mice.

Conclusions:

• Recombinant baculovirus and vaccinia virus systems successfully produced immunogenic PA.
• Baculovirus-derived PA is a valuable source for generating immunogenic PA.
• Vaccinia virus-PA recombinants show promise as live anthrax vaccine candidates for further development.