Identification and characterization of a porcine monocytic cell line supporting porcine reproductive and respiratory syndrome virus (PRRSV) replication and progeny virion production by using an improved DNA-launched PRRSV reverse genetics system.

In this study, an improved DNA-launched (plasmid DNA transfection-based) reverse genetics system with reduced cost and labor was developed for porcine reproductive and respiratory syndrome virus (PRRSV) by introduction of ribozyme elements at both termini of the viral genomic cDNA that were placed under the control of a eukaryotic hybrid promoter. The rescue efficacy of PRRSV with this system was approximately 10-50-fold higher than the in vitro-transcribed RNA-based system and the traditional DNA-launched system without the engineered ribozyme elements, as determined by reporter GFP level in transfected cells and the peak titer of the recovery virus. By using this new reverse genetics system, we identified and characterized a porcine monocytic cell line, 3D4/31, capable of supporting PRRSV replication, progeny virion production, and attachment on the cell surface. The establishment of this improved reverse genetic system and the identification of a porcine monocytic cell line supporting PRRSV replication will aid future studies of host-virus interaction of PRRSV.