Two phylogenetic trees based on the sequence of GP4 (Panel A) or M (Panel B) genes of selected type 2 PRRSV strains.

<p>The six parental viruses (VR2385 JX044140, VR2430 JX050225, MN184B DQ176020, FL-12 AY545985, JXA1 EF112445, and NADC20 JX069953) used in the DNA shuffling are indicated with boldface in the trees. The phylogenetic trees were constructed using the neighbor-joining method with bootstraps of 100 replicates. The numbers above each branch indicate the bootstrap values (percentage of consensus support in bootstrap).