Table 1.

Experimental design.

Group	1st vaccination	2nd vaccination	NADC30-like strain challenge	Sacrifice	No. of piglets
	4 weeks of age	7 weeks of age	10 weeks of age	12 weeks of age
SC	MEM medium	MEM medium	MEM medium	Sacrificed	5
PC	MEM medium	MEM medium	104.5 TCID50	Sacrificed	10
M1	Ingelvac PRRS® MLV one dose	MEM medium	104.5 TCID50	Sacrificed	10
MK1	Ingelvac PRRS® MLV one dose	2 ml KV (A company)	104.5 TCID50	Sacrificed	10-1a
MK2	Ingelvac PRRS® MLV one dose	2 ml KV (B company)	104.5 TCID50	Sacrificed	10

^aOne piglet in group MK1 was culled before the 2nd vaccination because of severe bacterial infection.