. 2019 Apr 23;97(7):2989–3006. doi: 10.1093/jas/skz135

Table 7.

Effects of dietary soy isoflavones level and porcine reproductive and respiratory virus (PRRSV) infection on serum viral load and presence of anti-PRRSV antibodies in weanling pigs

Item	Uninfected	PRRSV-infected				SEM	P-value
							Uninfected vs. infected control	Main effects²		Interaction
	Control¹	Control¹	Control + ISF¹	ETSBM¹	ETSBM + ISF¹			Soy Source	ISF	Soy Source × ISF
Ct value³
0 DPI	ND	ND	ND	ND	ND	1.52	0.812	0.968	0.968	0.999
3 DPI	ND	15.57*^b	16.44^b	18.81^b	12.10^a	1.41	<0.001	0.592	0.005	0.0001
6 DPI	ND	14.12*	15.39	15.37	12.66	1.41	<0.001	0.522	0.430	0.166
14 DPI	ND	18.75*	19.09	19.51	18.69	1.45	<0.001	0.860	0.795	0.948
ELISA S/P ratio⁴
6 DPI	–	0.087	0.070	0.040	0.045	0.10	–	0.661	0.935	0.974
14 DPI	–	1.565	1.736	1.475	1.440	0.171	–	0.027	0.412	0.080

*Difference (P ≤ 0.05) between uninfected and infected groups fed the control diet.

^abMeans without common superscript letter do differ at P ≤ 0.05.

Values represent least square means of 10 to 12 pigs. All pigs received allotted treatment diet starting −7 DPI. DPI = days post-inoculation; ISF = isoflavones; ELISA = enzyme-linked immunosorbent assay; ND = not detected.

¹The following diet names have been assigned to a respective experimental diet groups: Control: soy protein concentrate + no supplemented ISF, fed to both uninfected and PRRSV-infected control pigs; Control + ISF: soy protein concentrate + supplemented ISF, fed to PRRSV-infected pigs only; ETSBM: ETSBM + no supplemented ISF, fed to PRRSV-infected pigs only; ETSBM + ISF: ETSBM + supplemented ISF, fed to PRRSV-infected pigs only.

²Main effect of day post-inoculation (DPI); no 2- or 3-way interactive effects involving DPI were significant, so they were not included in the statistical model.

³Cycle threshold (Ct) values represent the mean number of PCR cycles required to detect the presence of PRRSV mRNA. A higher Ct value indicates less PRRSV DNA in the serum. No PRRSV DNA was detected in the serum of any uninfected pigs.

⁴IDEXX-ELISA S/P Ratio of 0.4 or greater is considered positive result. IDEXX ELISA assays were not performed on samples confirmed negative by qRT-PCR.