Anthrax vaccination induced anti-lethal factor IgG: fine specificity and neutralizing capacity

Area of Science:

• Immunology
• Vaccinology
• Microbial Pathogenesis

Background:

• Current anthrax vaccine (AVA) efficacy is measured by anti-protective antigen (anti-PA) antibody levels.
• Animal studies indicate antibodies to lethal factor (LF) can confer protection against anthrax.
• Understanding specific antibody responses is key to improving anthrax prevention and treatment.

Purpose of the Study:

• Identify individuals vaccinated with AVA who produce neutralizing antibodies.
• Determine specific antibody targets correlating with protection against anthrax.
• Investigate the role of anti-LF antibodies in immune response to anthrax vaccination.

Main Methods:

• Analyzed humoral immune responses in 1000 AVA-vaccinated individuals.
• Assessed in vitro neutralization capacity and correlated with vaccine history and demographics.
• Used overlapping decapeptide analysis to map LF antigenic regions.
• Tested affinity-purified antibodies against LF epitopes for protective efficacy in mouse models.

Main Results:

• Vaccine dose, time since vaccination, and PA titer correlated with neutralization.
• African Americans exhibited lower neutralizing activity than European Americans, suggesting genetic influence.
• Only 6.9% of individuals had moderate anti-LF IgG levels.
• Identified six common LF antigenic regions associated with high neutralizing activity.
• Antibodies targeting specific LF domains (PA binding, ADP-ribotransferase-like) protected mice from lethal toxin challenge.

Conclusions:

• Anti-LF antibodies contribute to protective immunity against anthrax.
• Specific epitopes on LF are critical targets for neutralizing antibodies.
• Findings support the development of improved anthrax vaccines and immunotherapies targeting both PA and LF.