Table 2. Association of Streptococcus suis serotype 2 STs and commonly used virulence markers in isolates from North America†.

ST	No. strains	Presence of factor-encoding gene									Phenotype
		sly	mrp variant‡						epf
			mrp	mrps	mrp*	mrp**	mrp***	ND			Hemolysis§	MRP¶	EF
1	11	11	9	0	0	0	0	2	11		11	9	11
25	36	0	0	1	1	8	23	3	0		0	0	0
28	49	0	42	6	1	0	0	0	3		0	49	0

†ST, sequence type; SLY, suilysin; MRP, muraminidase-released protein; ND, no amplification of the mrp gene was detected by PCR under the conditions used; EF, extracellular factor.
‡Variants of the mrp gene are those described by Silva et al. (20).
§Hemolysis of horse erythrocytes by the strains was considered to be an indication of the expression of SLY.
¶Molecular mass MRP variants identified by Western blotting were in agreement with those expected on the basis of the mrp gene variant identified by PCR.