Construction of the Recombinant Pseudorabies Virus TK~-/gG~-/GP5~+ Expressing GP5 of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and the Preliminary Study on Its Biological Characterization

Porcine reproductive and respiratory syndrome(PRRS) is one of the most economically significant diseases of the global pork-producing community.Pseudorabies virus(PRV),a member of alphaherpesvirus,is a novel viral vector to develop bivalent or multivalent genetic engineering vaccines.In the present study,we chose ORF5 gene encoding envelope protein GP5,the major immunogenic protein of PRRSV,as the target antigen.Based on homologous recombination,a recombinant PRV TK~-/gG~-/GP5~+ expressing GP5 was constructed using PRV TK~-/gG~-/LacZ~+ as a parental strain,and the recombinant virus was confirmed by PCR,Southern blot and Western blot.In addition,the one-step growth assay showed that the recombinant virus had growth properties identical to those of the parental virus,indicating that insertion of ORF5 gene in the gG focus of PRV did not affect its amplification.We further investigated the immunogenicity of the recombinant virus in mouse model and the results showed that low level of GP5-specific ELISA antibodies were detectable at 4 weeks after a boost and no detectable neutralizing antibodies were observed throughout the whole experimental period.