Vaccination of Mice with ORF5 Plasmid DNA of PRRSV; Enhanced Effects by Co-immunizing with Porcine IL-15

Abstract

The open reading frame (ORF) 5 of porcine reproductive and respiratory syndrome virus (PRRSV) encodes a major envelope glycoprotein designated GP5. The GP5 protein is a candidate for vaccinating against PRRSV infection. In this study, recombinant plasmids bearing the PRRSV GP5 gene (pVAX-GP5) or the porcine interleukin 15 gene (pVAX-IL15) were generated. Mice were vaccinated with these gene constructs singularly or in combination, and subsequent humoral and cellular immune responses were evaluated. Proliferation assays showed that the number of T lymphocytes in the peripheral blood and spleens of treated mice were elevated by pVAX-GP5 and significantly enhanced by combination therapy involving pVAX-IL15. Flow cytometry data showed that the numbers of CD4+ and CD8+ T cells were also higher in treated mice. Both pVAX-GP5 treatment alone and in combination with pVAX-IL15 resulted in elevated antibody levels as demonstrated by indirect ELISA. The pVAX-IL15 gene construct served as a molecular adjuvant in conjunction with the pVAX-GP5 to enhance the immune responses where intermediate doses of pVAX-IL15 were most effective.

• Porcine IL-15
• PRRSV
• GP5 gene
• DNA vaccine

ACKNOWLEDGMENTS

The work of X.R. is supported by funds provided by the Program for New Century Excellent Talents at the Heilongjiang Provincial University (1155–NCET–005).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.