Characterization of homologous and heterologous adaptive immune responses in porcine reproductive and respiratory syndrome virus infection

Table 7 Serum levels of IL-8 after challenge with PRRSV at 84 days after the initial inoculation

	Corrected† IL-8 levels in serum (pg/mL) N° responding pigs; Average ± standard deviation
Experiment 1 Group	Days post-challenge
	1*	2*	3	7¶	14
C1 + B	2/2^a 270 ± 108	2/2^a 424 ± 255	2/2^a 440 ± 434	2/2^a 470 ± 606	1/2 711 ± N.A.
A + A	0/4 N.A.	1/4 440 ± N.A.	2/4 272 ± 363	1/4 822 ± N.A.	1/4 124 ± N.A.
A + B	2/4 644 ± 479	3/4 194 ± 98	0/4 N.A.	0/4 N.A.	0/4 N.A.
Experiment 2 Group	Days post-challenge
	1	2	3	7	14¶
C2 + A	0/3^b N.A.	0/3^b N.A.	0/3^b N.A.	0/3^b N.A.	0/3 N.A.
B + B	3/4 249 ± 192	1/4 526 ± N.A.	2/4 212 ± 211	2/4 262 ± 247	3/4 297 ± 273
B + A	2/3 38 ± 2	1/3 667 ± N.A.	2/3 1088 ± 407	1/3 577 ± N.A	3/3 291 ± 117

† In order to account the pre-2nd challenge levels of a given cytokine, values (pg/mL) obtained with samples of day 0 (84 pi) (C1 + B:653 ± 66; A + A:796 ± 306; A + B:1062 ± 157; C2 + A:503 ± 133; B + B:187 ± 198; B + A:41.3 ± 0) were subtracted to the values obtained at days 1, 2, 3, 7 or 14, respectively for producing a corrected value (Corrected value for cytokine X = Concentration of cytokine X _{day n} - Concentration of cytokine X _{day 0}).
N.A. not applicable. Symbols (* p = 0.05; ¶ p < 0.05) show days for which statistical differences were observed between groups of a given experiment with regards to the proportion of positive pigs. Letters indicate statistically significant differences for the proportion of responding pigs for similar groups when comparing between experiments; i.e. naïve pigs inoculated with 3267 (C1 + B) vs. naïve pigs inoculated with 3262 (C2 + A). In this case, a,b correspond to p ≤ 0.1.

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