The strategy used for the development of PMA-qPCR assay for detection of Salmonella. Five primer pairs were designed in the conserved region near the 5′-end of invA gene (red block, from nucleotide positions 167 to 540). All five primer pairs shared the same forward primer and probe, and the reverse primers (A, B, C, D, and E) defined the amplicon length of amplicons A through E (Figure 5A); the numbers on amplicon D represent the locations of most of the SNPs found between the sequence of amplicon D in invA gene of Salmonella Typhimurium and the available invA gene sequences in GenBank. The number in parentheses indicates the amplicon length in bp (Figure 5B). Subjects in the figure are not in scale.