Table 1. T-lymphocyte responses from one-year-old gilts infected with PRRSV_SD23983 at 44 and 72 dpi in an IFN-gamma ELISpot assay against various type-1 and type-2 PRRSV isolates.

PRRSV type: strain	44 dpi PBMC			72 dpi PBMC
	Gilt 1	Gilt 2	Gilt 3	Gilt 1	Gilt 2	Gilt 3
Unstimulated: mean SFU (5 x SE)	2 (5)	6.5 (2.5)	15 (30)	4 (0)	28 (5)	30 (10)
1: PRRSVLV	43+*	11.5+	97+	73+	46+	>262+
1: PRRSV14003	6	6	7	4	24	89+
2: PRRSVVR2332	148+	61+	242+	>262+	>262+	>262+
2: PRRSV13392	199+	71+	262+	>262+	>262+	>262+
2: PRRSV53091	136+	72+	218+	>262+	>262+	>262+
2: PRRSV36509	>262+	69+	218+	>262+	>262+	>262+
2: PRRSV97-7895	>262+	61+	230+	>262+	>262+	>262+
2: PRRSVO-1	>262+	59+	>262+	>262+	>262+	>262+
2:PRRSV1403-02	>262+	61+	238+	>262+	>262+	>262+
2: PRRSV9530	>262+	58+	210+	>262+	>262+	>262+
2: PRRSV3606-98	165+	4	139+	>262+	>262+	>262+
2: PRRSVSD23983	259+	52+	226+	>262+	>262+	>262+

*Numbers are mean SFU/10⁶ PBMC minus the mean of the appropriate unstimulated control; those adjusted SFU means that were greater than the unstimulated control SFU mean plus 5 times the SE (standard error) were scored as positive and marked with a + in the table (for gilt 1 at 44 dpi those test SFU means >7 were positive; for gilt 2, >9; for gilt 3, >45 and so on). SFU means with >262+ indicate that the SFU was higher than the upper count limit for ELISpot reader.