Antigenic variation and genotype of isolates of porcine reproductive and respiratory syndrome virus in Korea

A panel of three anti-glycoprotein 5 (gp5) protein monoclonal antibodies (m Abs) (15, 28 and 246) and three anti-nucleocapsid (N) protein mAbs (SDOW17, VO17 and EP147) was used to investigate, by an indirect fluorescent antibo dy test, the antigenic variations of 50 Korean isolates of porcine reproduc tive and respiratory syndrome virus (PRRSV), and compare them with a us ATC C VR2332-derived attenuated vaccine strain and the reference European Lelys tad strain of PRRSV. A multiplex PCR assay for the differentiation of Europ ean and North American genotypes of PRRSV was used to determine the genotyp e of the 50 Korean isolates. Forty-six (92 per cent) of the 50 Korean isola tes shared the epitopes recognised by the anti-ttl protein mAb SDOW17. No r eactivity to the anti-gp5 and anti-N protein mAbs was observed with the oth er four isolates. Six distinct patterns could be identified on the basis of their reactivities with the anti-PRRSV mAbs. All 50 isolates were identifi ed as North American genotypes by the differential PCR.