Whole-genome sequencing of lineage 1 PRRSV SD at different passages
RNA was extracted from different SD passages: F5, F6, F8, F10, F20, F30, F40, F60, F80, F100, F105, F110, F125 (SD-R), F135 and F150. Reverse transcription PCR (RT–PCR), whole-genome sequencing, genome assembly and sequence alignments were performed as previously described (Zhang et al., 2019a). Detailed information on the whole-genome amplification primers is shown in a previous article (Zhang et al., 2019a).