Table 2.

Susceptibility of different PRRSV strains to antibody neutralization in vitro

Serum samplea	Neutralization titerb measured against the following virus:
	FL01	PRRSV-01	FL12	FL01/GP3-D131N	FL01/GP5-S51N	FL01/DM
1	2,048	2,048	8	256	128	64
2	8,192	4,096	8	1,024	256	64
3	1,024	2,048	≤4	256	256	64
4	1,024	2,048	8	128	256	32
Geometric mean	2,048 A	2,435.5 A	4.8 B	304.4 C	215.3 CD	53.8 D

^aSerum samples were obtained from pigs that had been infected with FL01 at 49 days postinfection (p.i.).

^bNeutralization titers were expressed as the reciprocal of the highest dilution that showed 90% or greater reduction in the number of fluorescent foci presenting in the control wells. Means with different letters (A to D) are significantly different (P < 0.05).