Fig. 1.

(A) Multiple sequence alignment of PRRSV N proteins. Highly conserved residues are shaded in black, whereas partially conserved residues are indicated by open boxes. The secondary structure of the C-terminal domain of VR2332 N protein is indicated at the top (Doan and Dokland, 2003) (PDB ID: 1P65). Alignment of the N sequence from type 2 strain VR2332 (GenBank ID: AY150564), the wild-type APRRS (GenBank ID: GQ330474) in this study and type 1 strain LV (GenBank ID: M96262). (B) Sequence alignment of the first 100 nt sequence of ORF7 of LV, APRRS and N-terminal deletion mutants, the identical sequence with LV is denoted as dot while natural sequence deletion compared with LV designated as dash line. The engineered deletion is represented by asterisk. The 34 nt that was documented to be essential for RNA replication of LV (Verheije et al., 2002) is indicated in the open box, the 7 nt sequence which had kissing interaction with 3′UTR is indicated by shaded box.