Fig. 5
Evaluation of Bcbva isolates by rhAmp genotyping assays. Five Bcbva, three Sterne-like, and four western African isolates were tested in triplicate with ~ 1.7 × 105 GE (equivalent to 1 ng of B. anthracis chromosomal DNA). Discrimination of western African strains remained unaltered by the presence of Bcvba in both assays and is depicted in blue along the top left corner of the y axis (Panels b and d). The 1352 assay produced Sterne-like amplification and discrimination of Bcbva strains (Panels a and b). Bcbva clustered with the three anthrose-positive (Sterne vaccine strain, laboratory Sterne and Ames) as illustrated by the red cluster along the x axis (b). Mutations in the primer sequences of the 892SNP, led to delayed amplification of the anthrose-producing allele in Bcbva as compared Sterne (Panel c). The decrease in fluorescence signal thus resulted in distinct clusters of Bcbva along the x axis (red dots) that were clearly separated from the higher fluorescence of the true Sterne cluster (Panel d). The true Sterne-like isolates, however, were mistyped as heterozygous (green cluster)