Representative 2-DE gel images of purified PRRSV virions. Protein (200 μg) was separated on the first dimensional pI 3-10 non linear IPG gels and second dimensional 5-17.5% continuous gradient vertical gels. The relative molecular mass is given on the right, while the isoelectric point is given on the top. Spots were analyzed by MALDI-TOF/TOF MS. The identified spots are numbered according to Table 2.