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

Table 1 Experimental design

	Groups	1^stChallenge* (0 pi)	2^ndChallenge* (84 pi)
Experiment 1 20 pigs	A	strain 3262	Group A + A (n = 4)
	A		Homologous challenge: strain 3262
	14 pigs^†		Group A + B (n = 4)
			Heterologous challenge: strain 3267
	C1	Placebo	Group C1 + B (n = 2)
	6 pigs^††		naïve controls: strain 3267
Experiment 2 11 pigs	B	strain 3267	Group B + B (n = 4)
	B		Homologous challenge: strain 3267
	8 pigs		Group B + A (n = 3**)
			Heterologous challenge: strain 3262
	C2	Placebo	Group C₂ + A (n = 3)
	3 pigs		naïve controls: strain 3262

* Inoculation was performed intranasally (2 mL; 1 mL/nostril) with a dosis of 5 × 10^5.0 TCID₅₀/mL of the corresponding strain.
** One pig died at 17 pi in the first inoculation.
† Six pigs were euthanized; three at 15 pi and three at 35 pi.
†† Four pigs were euthanized: two at 15 pi and two at +35 pi.

ISSN: 1297-9716