The Case for Developing Consensus Standards for Research in Microbial Pathogenesis: Bacillus anthracis Toxins as an Example

Characterization of the Native Form of Anthrax Lethal Factor for Use in the Toxin Neutralization Assay

“…In addition, the specific rLF potency, preparation (N-terminal residue content), or concentration did not appear to be important in ED 50 determination of such vaccines as long as the cytotoxic level of LT was maintained at 95 to 99% and the anti-LF fraction was substantially smaller (i.e., at least 10-fold) than that of the anti-PA fraction in test sera. Our conclusions are consistent with guidance presented in a commentary for B. anthracis toxin component consensus standards in which it was suggested that concentrations of LT components should be empirically derived per lot via checkerboard MLA (22).…”

“…This conclusion appears to have resulted in the use of the standard concentrations of 50 and 40 ng/ml for rPA and rLF-HMA, respectively, by the majority of laboratories reporting TNA validation and immunogenicity studies (15,(18)(19)(20)(21)(22)(23)(24). Our results are in agreement with such a concept, in that increasing rLF-A concentration decreased the measured potency (and, most likely, sensitivity) of anti-LF antibody neutralizing activity (Fig.…”

“…After a 4-h incubation, the degree of cytotoxicity is measured via a redox viability dye, which allows for a 50% effective dilution (ED 50 ) potency value to be obtained from the serum titration curve (18,19). The specific rPA and rLF concentrations of 50 and 40 ng/ml, respectively, have been used in most reported TNA validation and immunogenicity studies of animal and human vaccinations (15,(18)(19)(20)(21)(22)(23)(24). Although potency among rPA production lots is consistent (our unpublished observation), the potency of rLF is known to vary substantially among lots.…”

Hospital Microbiomics: Benchmarking from the First Longitudinal Study of Microbiome Dynamics among Patient, Staff and Hospital Habitats

“…6 Variable test results challenge scientific and regulatory objectives for quality and reproducibility, and standardization enables normalization of input and processes for comparison of results and conclusions between different studies. 7 For example, microbiological test result variability is accounted for by standardized averaging and two-fold tolerance in regulatory guidance and industry standards for quality control testing for pharmaceuticals. 8,9 Beyond the naturally high variability of microbial test samples, several options for computational analysis tools are available to extract the non-linear relationships and trending within large scale omics data.…”