Development of a sensitive and specific qPCR assay in conjunction with propidium monoazide for enhanced detection of live Salmonellaspp. in food

Table 1 Effect of amplicon length on PMA-mediated inhibition of DNA amplification from dead cells in qPCR targeting invA gene^a

Amplicon	Sequence of primers or probe	Position	Amplicon length (bp)	C_Tvalue with PMA	C_Tvalue w/o PMA	C_Tvalue difference^b
	Forward 5′-CGTTTCCTGCGGTACTGTTAATT^c	197-219
	Probe FAM-CCACGCTCTTTCGMGBNFQ^d	221-233
A	Reverse 5′-ACGACTGGTACTGATGATCGATAATGC	261-238	65	23.81	17.75	6.06
B	Reverse 5′-ATTTCACGGCATCGGCTTCAATC	293-270	97	29.96	18.41	11.55
C	Reverse 5′-GAATTGCCCGAACGTGGCGATAAAT	315-292	119	33.38	20.54	12.84
D	Reverse 5′-TCGCCAATAACGAATTGCCCGAAC	326-303	130	31.52	18.34	13.18
E	Reverse 5′-TCGCCAATAACGAATTGCCCGAAC	456-435	260	35.53	21.19	15.44

^ainvA gene sequence is from GenBank accession number M90846.
^bC_T value of untreated dead cells minuses C_T value of PMA-treated dead cells.
^cThe forward primer is shared by five reverse primers.
^dThe probe is shared by five primer pairs.