The infectious cDNA clone of commercial HP-PRRS JXA1-R-attenuated vaccine can be a potential effective live vaccine vector.

Multiple commercial porcine reproductive and respiratory syndrome (PRRS) modified live vaccines are currently utilized in Chinese swine herds due to the limited cross-protection of vaccines and coexistence of different PRRS viruses. In this study, an infectious cDNA clone of the highly pathogenic PRRS (HP-PRRS) vaccine JXA1-R strain was generated. We successfully rescued the virus from direct in vitro DNA transfection of rJXA1-R clone, which has similar growth kinetics to the parental JXA1-R virus in Marc-145 cells. To further evaluate the potential use of the cloned rJXA1-R virus as a live vector for foreign gene expression, the enhanced green fluorescent protein (EGFP) was inserted between non-structural and structural genes. Our results showed that the dynamic expression of EGFP can be visualized by live cell imaging system during the infection in Marc-145 cells. The availability of our cloned JXA1-R viruses provides a crucial platform to study the fundamental biology of HP-PRRS virus vaccine and also serves as a potential effective vector for developing live vector vaccines against swine pathogens.