Fig. 1.

(A) Phylogenetic analysis of the open reading frame (ORF) 5 in Korean type 1 porcine reproductive and respiratory syndrome viruses (PRRSVs). The phylogenetic tree was constructed with 117 PRRSV isolates from Korea and 46 PRRSV strains isolated from around the world. The VR-2332 strain was used as the outgroup. Gray boxes and bundle lines indicate genetic clusters (I, II, and III) of Korean isolates. Bootstrap values greater than 500 of 1,000 replicates are indicated. PRRSV strains are denoted as follows: name of the PRRSV strain/GenBank accession no./country name/collection time, year published, or vaccine. Isolates are denoted by serial numbers (Table 6). (B) Korean type 1 PRRSV isolates collected from 2007 to 2009 belonging to cluster I.