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

Abstract

Multiple commercial porcine reproductive and respiratory syndrome (PRRS) modified live vaccines (MLVs) are currently utilized in Chinese swine herds due to the limited cross‐protection of vaccines and coexistence of different PRRS viruses (PRRSVs). 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 nonstructural 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‐PRRSV vaccine and also serves as a potential effective vector for developing live vector vaccines against swine pathogens.