Duration of Protection of Rabbits after Vaccination with Bacillus anthracis Recombinant Protective Antigen Vaccine
Abstract
Long-term protection of rabbits that had been vaccinated with two doses of a recombinant protective antigen (rPA) vaccine was examined against an aerosol spore challenge with the Ames isolate of Bacillus anthracis at 6 and 12 months. At 6 months after the primary injection, survival was 74.1% (20/27) with quantitative ELISA titer of 22.3mug of anti-rPA IgG per millilitre and toxin neutralizing antibody (TNA) assay titer of 332. At 12 months after the primary injection, only 37.5% (9/24) of the rabbits were protected with quantitative ELISA titer of 19.8 g of anti-rPA IgG per millilitre and TNA assay titer of 286. There was a significant loss of protection (p=0.0117) and a significant difference in survival curves (p=0.0157) between the 6- and 12-month groups. When ELISA or TNA assay titer, gender, and challenge dose were entered into a forward logistic regression model, week 26 ELISA titer (p=0.0236) and week 13 TNA assay titer (p=0.0147) for the 6-month group, and week 26 ELISA titer (p=0.0326) and week 8 TNA assay titer (p=0.0190) for the 12-month group, were significant predictors of survival. Neither gender nor challenge dose were identified as having a statistically significant effect on survival. Booster vaccinations with rPA may be required for the long-term protection of rabbits against anthrax.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 27, 2005
- Accession Number
- ADA449400
Entities
People
- B. E. Ivins
- G. P. Andrews
- M. L. Pitt
- P. F. Fellows
- S. F. Little
- S. L. Norris
- W. M. Webster
Organizations
- United States Army Medical Research Institute of Infectious Diseases