Table 3.

Effect of amplicons of different length on signal suppression of Salmonella dead cells by PMA-qPCR.

Amplicon	Sequence of primers or probe (5′–3′)	Position in invAa	Amplicon length (bp)	CT value		Signal suppression (ΔCT)b (PMA efficiency)
				PMA-treated (PMA effect)	Untreated (qPCR efficiency)
A	Forward 5′-CGTTTCCTGCGGTACTGTTAATT	197–219	65	23.81	17.75	6.06
	Reverse 5′-ACGACTGGTACTGATGATCGATAATGC	261–238
	Probe FAM-CCACGCTCTTTCGMGBNFQ	221–233
B	Forward 5′-CGTTTCCTGCGGTACTGTTAATT	197–219	97	29.96	18.41	11.55
	Reverse 5′-ATTTCACGGCATCGGCTTCAATC	293–270
	Probe FAM-CCACGCTCTTTCGMGBNFQ	221–233
C	Forward 5′-CGTTTCCTGCGGTACTGTTAATT	197–219	119	33.38	20.54	12.84
	Reverse 5′-GAATTGCCCGAACGTGGCGATAAAT	315–292
	Probe FAM-CCACGCTCTTTCGMGBNFQd	221–233
Dc	Forward 5′-CGTTTCCTGCGGTACTGTTAATT	197–219	130	31.52	18.34	13.18
	Reverse 5′-TCGCCAATAACGAATTGCCCGAAC	326–303
	Probe FAM-CCACGCTCTTTCGMGBNFQ	221–233
E	Forward 5′-CGTTTCCTGCGGTACTGTTAATT	197–219	260	35.53	21.19	15.44
	Reverse 5′- GACCACGGTGACAATAGAGAAG	456–435
	Probe FAM-CCACGCTCTTTCGMGBNFQ	221–233

^ainvA gene sequence is from GenBank accession number M90846.

^bΔC_T value was created by (C_T value of PMA-treated dead cells -C_T value of untreated dead cells).

^cBold-faced information is for the amplicon selected as the optimized amplicon in PMA-qPCR.