Correlation analysis, analysis of covariance, and the Altman-Bland empirical method have been used to elucidate the relationship between antigen-specific ELISA and a lethal toxin neutralization assay (TNA) of anthrax vaccine potency measurements. Both assays measure the antibody response to Protective Antigen (PA) in mice immunized once with either Anthrax Vaccine Adsorbed (AVA) or an in-house recombinant PA vaccine (rPAV) at various doses.

Coefficients of correlation and linear regression equations for the two assays were found to be immunization dose dependent. ELISA and TNA results may not be strictly interchangeable for this animal model.  Further experiments are needed to study the biological mechanisms underlying the relationships found between the assays and to understand the meaning and relevance of these results for vaccine-testing purposes.